Issue Vol. 10, 04 2012

ATM Letters July/August Issue, 2012 1

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Super Moon? How About a Super Sun! On May 5, 2012, while everyone else was waiting for the “Super Moon”astrophotographer Alan Friedman was out capturing this super image of a super Sun from his back yard in Buffalo,NY! Taken with a specialized telescope that can image the Sun in hydrogen alpha light, Alan’s photo shows theintricate detail of our home star’s chromosphere - the layer just above its “surface”, or photosphere.

Prominences can be seen rising up from the Sun’s limb in several places, and long filaments - magnetically-suspendedlines of plasma - arch across its face. The “fuzzy” texture is caused by smaller features called spicules and fibrils,which are short-lived spikes of magnetic fields that rapidly rise up from the surface of the Sun. On the left side itappears that a prominence may have had just detached from the Sun’s limb, as there’s a faint cloud of materialsuspended there. Credit: Alan Friedman/UT



Amazing Astrophoto: The Phases of Venus. Wow! Take a look at how Venus has changed in the night sky the pastfive months! “The Planet Venus, The Roman goddess of love and beauty and the closest planet to us - especially nowjust as it gets closest - will transit across the Sun soon,” said astrophotographer Efrain Morales. “This sequence is afive month transition showing its size continuing to grow and its crescent getting thinner as time progresses.

Credit: Efrain Morales/UT



Stunning Astrophoto: Auroral Explosion of Color. This gorgeous and unusual aurora display was captured byBrendan Alexander from the North Coast of Donegal, Ireland. “We were treated to an absolutely stunning auroradisplay on the morning of the 24th of April 2012,” Brendan wrote on UT Flickr page. “Easily the best I have seen in myeventful four years of sky watching. The display started off strong at nightfall (22:00 UT) with intense and almoststatic rays. However shortly after magnetic midnight the aurora came to life, complete with waving curtains,shimmering rays, vivid colours and pulsating heart. A spellbinding and enrolling time was endured from dusk to dawn.A Stunning display to remember during the bright summer months ahead.” Brendan used a Canon 1000D camera witha Sigma 20mm F1.8 lens. Exposure: 8 – 11 sec ISO 1600. Credit: Brendan Alexander/UT


HistoryAndrew Ainslie Common: The Common ManAndrew Ainslie Common (1841-1903) was a pioneer in theconstruction of large silvered mirror telescopes. He showed thepotential of such instruments to photograph the heavensprovided they were accurately driven and situated in a suitableobserving location. Two of his telescopes are still in operationtoday, the 36-inch ‘Crossley’ reflector at the Lick Observatoryin Calfifornia and the 60-inch ‘Rockefeller’ reflector at theBoyden Observatory, Bloemfontein, South Africa...

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Globular Cluster and Cyber SkySimulation globular clusters and sky pictorially …

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MODAS NG Update – Mirror TestingFoucault test, Ronchigrams mirror real profile …

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RoboScopes - Real Armchair AstronomyRobotic telescopes can be fun, they can lead to amazing things …

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Vertical Direct North/South SundialA Sundial primer …

2233Troughton & Simms Dividet-Lens DoubleImage MicrometerOptical analysis …

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Orbital MechanicsStudy of the motions of artificial satellites and space vehicles …

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See also…

RESOURCESEDITOR NOTESNEWSBOOKSGALLERY

ADVERISEMENTS

NEXT ISSUE

OONN TTHHEE CCOOVVEERR

ATMLJ10th AnniversaryLooking back …Moving Forward

Credit: Pencho Markishki

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Examplessw_win_moonphase.zip – Moon phase by Ivan Krastev (3x - Desktop, small and large Widget)

sw_xls_vertdial.zip – Vertical Direct North/South sundial by Carl Sabanski (Excel sheet)

Tools gift_moonphasewgl.zip – Large Moon Phase widget by Ivan Krastev

e-Articles, e-Books us_patents.zip - Patent, 2549158 - Wide-Angle Eypiece Lens System (PDF)

- Patent, 2576011 - Catadioptric Optical System (PDF)- Patent, 2520636 - Optical Objective (PDF)- Patent, 2520635 - Optical System (PDF)- Patent, 2520633 - Optical System (PDF)

ebooks.zip - Eng, Antiquarian - Astronomy - New and Original Theories of the Great (EPUB)Physical Forces - Rogers, Henry Raymond

- Eng, Antiquarian - Astronomy - Side-lights on Astronomy and Kindred Fields(EPUB)of Popular Science - Newcomb, Simon

- Eng, Antiquarian - Astronomy - Recreations in Astronomy - Warren, Henry (EPUB)- Eng, Antiquarian - Optics - Light waves and their uses - A. A. Michelson (DJVU)

Enjoy!

We believe that most of the texts and images are in the public domain. We donot own the copyright to the texts and images used in ATM Letters Journal.

We have not kept a record of where we found any of the texts and images wehave used.

If you believe that you own the rights to any of the texts and images we use,please contact us and we will add an acknowledgement.

All logos and trademarks in ATM Letters Journal are property of theirrespective owner.

Universe Today allows reprinting of all his stories, when a credit says thatoriginal story was originally published on Universe Today.


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What is the ATM Letters?

This is electronic based Journal (100% recycling) Available in Adobe PDF (in the feature like free iBook from the Apple Store) It comes out in the feature 3 times in year (the commercial release was available bi-monthly).

What you will find in ATM Letters? Which are the journal columns? Cover Page

This is the journal’s title page, includes journal logo, issue label, big format picture and list of issue’shighlights. This page is followed often by three additional pages with some amazing amateurastrophotography images.

ContentsThis is the issue’s columns summary with paging. Also thumbnail screen shots and very shortdescription will be given. This page is followed by page with sort description of the issue’s resourceslike freeware ATM software written by the editor or other ATM, different tools, electronically articlesand free e-books.

Editor NotesHere is the editor’s place for short announcements.

Letters to the EditorHere is the place, where the reader can report shortly all related to telescope making, interestinglinks, journal opinion, notice about present issues or articles, short information or interesting notices.Up to two sites are reserved

Small ATM CompaniesHere I reserved place for your ATM Group, Association, Observatory or small Company, where youcan tell in brief to other ATM about your establishing, experience, interest, works, friends, telescopesand meetings. Photos are welcomed. Up to two sites are reserved.

GlossaryHere is the place for shortly and easy described optics key words, for examples aberration types,sign conventions, types of optical surfaces, kind of telescopes etc. Diagrams and pictures will beincluded.

The next four columns are the most impressive journal sections: Praxis

This column allows you make public to other reader your own built telescope, experience in design,constructing, making, grinding, polishing, testing etc. Pictures, schemes and graphics are highlyrecommended.

Back to TheoryHere is the Treasure Island for all advanced ATM. Any article will include all formulas needed toperform own design and analysis of your telescope. Here will be reviewed in details any telescopesystem used by the amateur astronomers and professionals, design of eyepieces, field correctors,mirror testing, baffling and collimating etc. Also this section will be edited in connections with thenext column, where in the same or the next issue will appear full working program written in differentprogramming languages.

Astronomical, Numerical and Optical ComputingThis is the programmer corner, maybe the most practical column, which includes useful telescopedesigns, analyses and testing BASIC programs suggested by readers or written by me. All programswill be here (or in the column Back to Theory) theoretical explained.I will write you additional the same programs also in pascal, java (applets), java and html scripts(calculators), which you can use free in your home page. MS-Excel fans will be supplied with a lot ofspreadsheets.Here is also place to introduce you in easy way in some numerical methods, used by the amateurs,like interpolation (needed by curve fitting), integration (needed for calculation of wave aberration),3D graphic plotting etc. Astronomical calculations will be discussed too.


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Computer and TelescopesThis column will report you all about existing telescope design, analysis and mirror testing packages,

description, program features, mastering of the programs, design file formats, useful types & tricks, discussing useful designs.

This column has two major sub columns called: “Software Overview” and “Test Report”. All Discussed designs, will be tested with different packages (for example MODAS, ZEMAX, OSLO,

OpTaliX, ATMOS etc.) and the results finally compared. News

This column will inform you about new books publication, new software releases, and latest newsfrom space, astronomy, and new technologies. A part of this column is the “Eyes of the World”,“Telescope Review”, “and “Scientific Instruments” (both antiques and modern).

BibliographyHere you will find quantity bibliographic data about history of optics, telescopes, telescope making,astronomy, famous optician and astronomers, old observatories, antique telescopes, books andmagazines bibliography etc.

This column has three major sub columns called “Pioneers in Optics”, Rambling “through the Years” and “A Brief History …”


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Dear ATMLJ reader! Dear Friends!

Looking BackTen years ago, in one hot August summer’sday of 2003, I decided the beginning editingof my own Journal for amateur astronomersand telescope makers, focused on telescopemaking, telescope design and optics ingeneral, astronomical, optical and numericalcomputing, history of telescopes, optics andastronomy in general and many other relatedstuff.

At that time I have had not any idea, howlong I will be available to make this job (todaytoo ). After my first successful projectMODAS this was my second project but withone difference - without any experience inthis area.

The first problem with my Journal was thename that I choose - ATM Journal. Not onlyat this time, but later and today too, was notavailable any other journal with such name. Afew weeks after the promotion of my journal,I received via email, the first statement - Ican't use the name ATM Journal because it is

copyright owned by Bill Cook, former editor of not more existing ATM Journal. So I had chosenthe name ATM Letters Journal or as you known today as ATMLJ. All this was not new for me, afew years before, similar people from the ATM community tried to do the similar things with myMODAS. Also the moving forward is often not problem-free.

The copyright will be our great problem in the feature, in any kind, for any from us in our dailyliving. This is one of the reasons to release my journal free for a few years beginning with thisanniversary issue (see below).

Regarding to the copyright, a joke that I read a few weeks (Projects ACTA/PIPA/SOPA):"Conversation between two friends, who says one to the other:- I gotta tell you, I have a huge problem with my company logo.- Why?- Because it is round like these by Pepsi..."

In the first issue of ATMLJ I defined the columns that I will edit in the feature and some nameswas changed with the years. I think that with the time, progressed too the face (layout) ofATMLJ. From begin I choose column's layout with two rows, looking very professional (similarto those from Applied Optics Journal and JOSA).

Many readers say that the printing issue looks great. Other says, they have shifted to ATMLJafter they cannot find more interesting stuff in Sky & Telescope and Astronomy magazines. Orother what I can say is that about 75% from all readers are subscriber since August 2003!



Thank you for the faithful and the good words all these years!

Nevertheless, I know that many things could be made better in ATMLJ and this will be my task inthe feature. My great wish is more and more amateurs to submit his articles. Maybe this willhappen next year (2013), were ATMLJ is free. I have a large database on amateurs (over 1000)interested on ATMLJ, and I’m sure all will enjoy the magazine.

But maybe the reason for the low activity of the amateur astronomers is the hard time were weliving, many of us has many problems than enjoying his hobby. The possibility to buy a telescopein a supermarket (China made it possible) has negative effects on the offspring of young amateurastronomers and telescope makers. If you look to the most popular atm forums, a great part fromthe community is in the age between 40 and 60. The same is also true for the owner of theavailable home pages of active ATM. What a pity!

Maybe it is unknown for the readers that ATMLJ was always free for many amateur astronomersand telescope makers around the world, people that have had not the possibility to pay by one orother reason, but people that love his hobby. For me was great pleasure to help on such peoplewith free subscription!

I hope we can look back again in 10 years! I'm sure!

Moving ForwardMaybe some of you have felt it, that in the past and this year, I'm tired. Often I could notcomplete the issue ready in a time. Actually, the tiredness is not only one reason. My biggestproblem is that in the last 10 years I have to work 6 days weekly. So I have to recover me only onSunday. But if a task is a fun, you do not feel the tiredness, not at the beginning. My free time isvery limited for so many things I wish do.

I decided in the feature for a while to reduce the number of issues to 2-3 yearly (spring, summerand Christmas). Of course I will try to put the stuff from 6 issues in these two or three issues. Allissues will be available for free and you will receive still notification, when a new issue is available.Of course reader currently subscribed for 2013 will receive his money back. The difference fromearlier is that I'm not under the pressure that issue is not completed in a time and I will haveadditional time for other projects.In this year I discovered again the fun by free programming (programming something when Ihave time and inclination for that) and I wish support you with many new free programs andtools related to the astronomy, optics and science in general for both Windows, Mac OS X andiOS platforms. Beginning with this anniversary issue you can enjoy a lot of tools that Iprogrammed especially for the ATMLJ readers.

In the next year I will spend my free time for finishing the development of my MODAS NG. Buthere is one restriction related to the license. In the next few years will be not available commercialversion of MODAS NG. Of course the users that currently ordered MODAS NG ATM will receiveregular update until the development is finished. Don't worry, MODAS will be available for thisperiod as freeware version with limitation on used surfaces number and working like demo versionover this limitation.

The free release of MODAS NG and the magazine has some personal backgrounds too(unfortunately again problems with my ex-wife) and the problem should no more exists in fewyears.



Additional to my MODAS and ATMLJ, I wish to start two other projects (very, very old wish fromme):

1. Writing of optical design book "Astronomical Optics" in conjunction with MODAS NG as a tool inmain focus and history of telescopes and their builder and history of optics in general too. Ofcourse here exist many similar books about this stuff, but I have some other ideas that not occurin any from them.

2. Start new project called "The Human of Dawn" related to Archaeology, Paleontology andAlternative History and History in general. This project will have own home page and will includethe development of software tools with the same name and will allows professionals and amateursinterested in this area to analyze great amount of data and evidences with scientific methods andart given never before. Such tools should be great help for all that look deep back into our originand search answers of questions like “Who are we?”, “Where we come from?”, “Where are wegoing?”. All these evidences are there in front of our eyes, one only has to look right. Did youknow that over 20 000 000 prehistoric drawings on rocks and in caves around the world exist, andonly a fraction of it has been explored or the ortodox archaeology wish not to be explored? Andeach drawing can tell us a story!

I hope that what I am doing now is not a step back, but moving forward!

Best regards

IvanAustria, Moedling, 22 August 2012



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Using and getting the most out ofrobotic astronomy

Whilst nothing in the field of amateur astronomybeats the feeling of being outside looking up at thestars, the inclement weather many of us have toface at various times of year, combined with thetask of setting up and then packing awayequipment on a nightly basis, can be a drag.Those of us fortunate enough to haveobservatories don’t face that latter issue, but stillface the weather and usually the limits of our ownequipment and skies.Another option to consider is using a robotictelescope. From the comfort of your home you canmake incredible observations, take outstandingastrophotos, and even make key contributions toscience!The main elements which make robotic telescopesappealing to many amateur astronomers arebased around 3 factors. The first is that usually,the equipment being offered is generally vastlysuperior to that which the amateur has in theirhome observatory. Many of the robotic commercialtelescope systems, have large format mono CCDcameras, connected to high precision computercontrolled mounts, with superb optics on top,typically these setups start in the $20-$30,000price bracket and can run up in to the millions ofdollars.Combined with usually well defined and fluidworkflow processes which guide even a noviceuser through the use of the scope and thenacquisition of images, automatically handling suchthings as dark and flat fields, makes it a mucheasier learning curve for many as well, with manyof the scopes specifically geared for early gradeschool students.The second factor is geographic location. Many ofthe robotic sites are located in places whereaverage rainfall is a lot lower than say somewherelike the UK or North Eastern United States forexample, with places like New Mexico and Chile in

Top/Bottom: The Faulkes Telescope North/South. The two FaulkesTelescopes have now been incorporated into the even grander scheme ofthe Las Cumbres Observatory Global Telescope Network (LCOGT.net).Established by Wayne Rosing, ex-vice president of software engineering atGoogle, this project will see more than 30 additional telescopesconstructed around the world ranging in size from 40cm to 1m and madeavailable to schools from all countries for educational purposes.

Credit: Faulkes Telescope/LCOGT


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The LT's primary mirror undergoing final cleaning by ING staff (Juerg Rey at right), before being transferred into the WHT's coating unit on La Palma.Credit: Liverpool Telescope/A. Scott


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The Liverpool Telescope as seen from the window of the Mercator Telescope's kitchen. Credit: Liverpool Telescope/J. Marchant


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The Liverpool Telescope. Credit: Liverpool Telescope/R. Smith


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particular offering almost completely clear dryskies year round. Robotic scopes tend to see moresky than most amateur setups, and as they arebeing controlled over the Internet, you yourselfdon’t even have to get cold outside in the depths ofwinter. The beauty of the geographic locationaspect is that in some cases, you can do yourastronomy during the daytime, as the scopes maybe on the other side of the world.The third is ease of use, as it’s nothing more thana reasonably decent laptop, and solid broadbandconnection that’s required. The only thing youneed worry about is your internet connectiondropping, not your equipment failing to work. Withscopes like the Faulkes or Liverpool Telescopes,ones I use a lot, they can be controlled fromsomething as modest as a netbook or even anAndroid/iPad/iPhone, easily. The issues with CPUhorsepower usually comes down to the imageprocessing after you have taken your pictures.Software applications like the brilliant Maxim DL byDiffraction Limited which is commonly used forimage post processing in amateur and evenprofessional astronomy, handles the FITS file datawhich robotic scopes will deliver. This is commonlythe format images are saved in with professionalobservatories, and the same applies with manyhome amateur setups and robotic telescopes. Thissoftware requires a reasonably fast PC to workefficiently, as does the other stalwart of theimaging community, Adobe Photoshop. There aresome superb and free applications which can beused instead of these two bastions of the imagingfraternity, like the excellent Deep Sky stacker, andIRIS, along with the interestingly named “GIMP”which is variant on the Photoshop theme, but freeto use.Some people may say just handling image data ora telescope over the internet detracts from realastronomy, but it’s how professional astronomerswork day in day out, usually just doing datareduction from telescopes located on the otherside of the world. Professionals can wait years toget telescope time, and even then rather thanactually being a part of the imaging process, willsubmit imaging runs to observatories, and wait forthe data to roll in. (If anyone wants to argue thisfact…just say “Try doing eyepiece astronomy withthe Hubble”)The process of using and imaging with a robotictelescope still requires a level of skill anddedication to guarantee a good night of observing,be it for pretty pictures or real science or both.Location Location LocationThe location for a robotic telescope is critical as ifyou want to image some of the wonders of theSouthern Hemisphere, which those of us in the UK

Top: A look at the Faulkes Telescope South inside. Middle: Screenshot ofthe Faulkes Telescope realtime interface. Bottom: iTelescope systems arelocated all over the globe.

Credit: Faulkes Telescope/LCOGTiTelescope project


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or North America will never see from home, thenyou’ll need to pick a suitably located scope. Timeof day is also important for access, unless thescope system allows an offline queuemanagement approach, whereby you schedule itto do your observations for you and just wait forthe results. Some telescopes utilise a real timeinterface, where you literally control the scope livefrom your computer, typically through a webbrowser interface. So depending on where in theworld it is, you may be in work, or it may be at avery unhealthy hour in the night before you canaccess your telescope, it’s worth considering thiswhen you decide which robotic system you wish tobe a part of.Telescopes like the twin Faulkes 2-metre scopes,which are based on the Hawaiian island of Maui,atop a mountain, and Siding Spring, Australia, nextto the world famous Anglo Australian Observatory,operate during usual school hours in the UK, whichmeans night time in the locations where thescopes live. This is perfect for children in westernEurope who wish to use research gradeprofessional technology from the classroom,though the Faulkes scopes are also used byschools and researchers in Hawaii.The type of scope/camera you choose to use, willultimately also determine what it is you image.Some robotic scopes are configured with wide fieldlarge format CCD’s connected to fast, low focalratio telescopes. These are perfect for creatinglarge sky vistas encompassing nebulae and largergalaxies like Messier 31 in Andromeda. Forimaging competitions like the AstronomyPhotographer of the Year competition, these widefield scopes are perfect for the beautiful skyscapesthey can create.Scopes like the Faulkes Telescope North, eventhough it has a huge 2m (almost the same size asthe one on the Hubble Space Telescope) mirror, isconfigured for smaller fields of view, literally onlyaround 10 arcminutes, which will nicely fit inobjects like Messier 51, the Whirpool Galaxy, butwould take many separate images to imagesomething like the full Moon (If Faulkes North wereset up for that, which it’s not). It’s advantage isaperture size and immense CCD sensitivity.Typically our team using them is able to image amagnitude +23 moving object (comet or asteroid)in under a minute using a red filter too!A field of view with a scope like the twin Faulkesscopes, which are owned and operated byLCOGTis perfect for smaller deep sky objects and my owninterests which are comets and asteroids.Manyother research projects such as exoplanets andthe study of variable stars are conducted usingthese telescopes.Many schools start out imaging

Global Rent-A-Scope interface

nebulae, smaller galaxies and globular clusters,with our aim at the Faulkes Telescope Projectoffice, to quickly get students moving on to morescience based work, whilst keeping it fun. Forimagers, mosaic approaches are possible to createlarger fields, but this obviously will take up moreimaging and telescope slew time.Each robotic system has its own set of learningcurves, and each can suffer from technical orweather related difficulties, like any complex pieceof machinery or electronic system. Knowing a bitabout the imaging process to begin with, sitting inon other’s observing sessions on things like Slooh,all helps. Also make sure you know your targetfield of view/size on the sky (usually in either rightascension and declination) or some systems havea “guided tour mode” with named objects, andmake sure you can be ready to move the scope toit as quickly as possible, to get imaging. With thecommercial robotic scopes, time really is money.Magazines like Astronomy Now in the UK, as wellas Astronomy and Sky and Telescope in theUnited States and Australia are excellentresources for finding out more, as they regularlyfeature robotic imaging and scopes in their articles.Online forums like cloudynights.com andstargazerslounge.com also have thousands ofactive members, many of whom regularly userobotic scopes and can give advice on imagingand use, and there are dedicated groups forrobotic astronomy like the Online AstronomicalSociety. Search engines will also give usefulinformation on what is available as well.To get access to them, most of the robotic scopesrequire a simple sign up process, and then theuser can either have limited free access, which isusually an introductory offer, or just start to pay fortime. The scopes come in various sizes and qualityof camera, the better they are, usually the moreyou pay. For education and school users as well


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as astronomical societies, The Faulkes Telescope(for schools) and the Bradford Robotic scope bothoffer free access, as does the NASA funded MicroObservatory project. Commercial ones likeiTelescope, Slooh and Lightbuckets provide arange of telescopes and imaging options, with awide variety of price models from casual toresearch grade instrumentation and facilities.

So what about my own use of RoboticTelescopes?

Personally I use mainly the Faulkes North andSouth scopes, as well as the Liverpool La PalmaTelescope. I have worked with the FaulkesTelescope Project team now for a few years, andit’s a real honour to have such access to researchgrade intrumentation. Our team also use theiTelescope network when objects are difficult toobtain using the Faulkes or Liverpool scopes,though with smaller apertures, we’re more limitedin our target choice when it comes to very faintasteroid or comet type objects.After having been invited to meetings in anadvisory capacity for Faulkes, late in 2011 I wasappointed pro am program manager, co-ordinatingprojects with amateurs and other research groups.With regards to public outreach I have presentedmy work at conferences and public outreachevents for Faulkes and we’re about to embark on anew and exciting project with the European SpaceAgency whom I work for also as a science writer.My use of Faulkes and the Liverpool scopes isprimarily for comet recovery, measurement(dust/coma photometry and embarking onspectroscopy) and detection work, those icy solarsystem interlopers being my key interest. In thisarea, I co-discovered Comet C2007/Q3 splitting in2010, and worked closely with the amateurobserving program managed by NASA for comet103P, where my images were featured in NationalGeographic, The Times, BBC Television and alsoused by NASA at their press conference for the103P pre-encounter event at JPL.The 2m mirrors have huge light grasp, and canreach very faint magnitudes in very little time.When attempting to find new comets or recoverorbits on existing ones, being able to image amoving target at magnitude 23 in under 30s is areal boon. I am also fortunate to work alongsidetwo exceptional people in Italy, Giovanni Sosteroand Ernesto Guido, and we maintain a blog of ourwork, and I am a part of the CARA research groupworking on comet coma and dust measurements,with our work in professional research papers suchas the Astrophysical Journal Letters and Icarus.The Imaging ProcessWhen taking the image itself, the process startsreally before you have access to the scope. Knowing the field of view, what it is you want toachieve is critical, as is knowing the capabilities ofthe scope and camera in question, andimportantly, whether or not the object you want toimage is visible from the location/time you’ll beusing it.

Knowing the field of view, what it is you want toachieve is critical, as is knowing the capabilities ofthe scope and camera in question, andimportantly, whether or not the object you want toimage is visible from the location/time you’ll beusing it.First thing I would do if starting out again is lookthrough the archives of the telescope, which areusually freely available, and see what others haveimaged, how they have imaged in terms of filters,exposure times etc, and then match that againstyour own targets.Ideally, given that in many cases, time will becostly, make sure that if you’re aiming for a faintdeep sky object with tenuous nebulosity, you don’tpick a night with a bright Moon in the sky, evenwith narrowband filters, this can hamper the finalimage quality, and that your choice ofscope/camera will in fact image what you want itto. Remember that others may also want to usethe same telescopes, so plan ahead and bookearly. When the Moon is bright, many of thecommercial robotic scope vendors offer discountedrates, which is great if you’re imaging somethinglike globular clusters maybe, which aren’t asaffected by the moonlight (as say a nebula wouldbe)Forward planning is usually essential, knowing thatyour object is visible and not too close to anyhorizon limits which the scope may impose, ideallypicking objects as high up as possible, or rising togive you plenty of imaging time. Once that’s alldone, then following the scope’s imaging processdepends on which one you choose, but withsomething like Faulkes, it’s as simple as selectingthe target/FOV, slewing the scope, setting thefilter, and then exposure time and then waiting forthe image to come in.The number of shots taken depends on the timeyou have. Usually when imaging a comet usingFaulkes I will try to take between 10 and 15images to detect the motion, and give me enoughgood signal for the scientific data reduction whichfollows. Always remember though, that you’reusually working with vastly superior equipmentthan you have at home, and the time it takes toimage an object using your home setup will be alot less with a 2m telescope. A good example isthat a full colour high resolution image ofsomething like the Eagle Nebula can be obtainedin a matter of minutes on Faulkes, in narrowband,something which would usually take hours on atypical backyard telescope.For imaging a non moving target, the more shots infull colour or with your chosen filter (HydrogenAlpha being a commonly used one with Faulkes fornebula) you can get the better. When imaging in


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colour, the three filters on the telescope itself aregrouped into an RGB set, so you don’t need to setup each colour band. I’d usually add a luminancelayer with H-Alpha if it’s an emission nebula, ormaybe a few more red images if it’s not forluminance. Once the imaging run is complete, thedata is usually placed on a server for you tocollect, and then after downloading the FITS files,combine the images using Maxim (or other suitablesoftware) and then on in to something likePhotoshop to make the final colour image. Themore images you take, the better the quality of thesignal against the background noise, and hence asmoother and more polished final shot.Between shots the only thing that will usuallychange will be filters, unless tracking a movingtarget, and possibly the exposure time, as somefilters take less time to get the requisite amount oflight. For example with a H-Alpha/OIII/SII image,you typically image for a lot longer with SII as theemission with many objects is weaker in this band,whereas many deep sky nebula emit strongly inthe H-Alpha.The Image ItselfAs with any imaging of deep sky objects, don’t beafraid to throw away poor quality sub frames (theshorter exposures which go to make up the finallong exposure when stacked). These could beaffected by cloud, satellite trails or any number offactors, such as the autoguider on the telescopenot working correctly. Keep the good shots, anduse those to get as good a RAW stacked dataframe as you can. Then it’s all down to postprocessing tools in products likeMaxim/Photoshop/Gimp, where you’d adjust thecolours, levels, curves and possibly use plug ins tosharpen up the focus, or reduce noise. If it’s purescience your interested in, you’ll probably skipmost of those steps and just want good, calibratedimage data (dark and flat field subtracted as wellas bias)The processing side is very important when takingshots for aesthetic value, it seems obvious, butmany people can overdo it with image processing,lessening the impact and/or value of the originaldata. Usually most amateur imagers spend moretime on processing than actual imaging, but thisdoes vary, it can be from hours to literally daysdoing tweaks. Typically when processing an imagetaken robotically, the dark and flat field calibrationare done. First thing I do is access the datasets asFITS files, and bring those in to Maxim DL. Here Iwill combine and adjust the histogram on theimage, possible running multiple iterations of a de-convolution algorithm if the start points are not astight (maybe due to seeing issues that night).Once the images are tightened up and then stretch-

ed, I will save them out as FITS files, and using thefree FITS Liberator application bring them in toPhotoshop. Here, additional noise reduction andcontrast/level and curve adjustments will be madeon each channel, running a set of actions knownas Noels actions (a suite of superb actions by NoelCarboni, one of the worlds foremost imagingexperts) can also enhance the final individual redgreen and blue channels (and the combined colourone).Then, I will composite the images using layers intoa colour final shot, adjusting this for colour balanceand contrast. Possibly running a focusenhancement plug in and further noise reduction.Then publish them via flickr/facebook/twitter and/orsubmit to magazines/journals or scientific researchpapers depending on the final aim/goals.Serendipity can be a wonderful thingI got in to this quite by accident myself…. In March2010, I had seen a posting on a newsgroup thatComet C/2007 Q3, a magnitude 12-14 object atthe time, was passing near to a galaxy, and wouldmake an interesting wide field side by side shot.That weekend, using my own observatory, Iimaged the comet over several nights, and noticeda distinct change in the tail and brightness of thecomet over two nights in particular.A member of the BAA (British AstronomicalAssociation), seeing my images, then asked if Iwould submit them for publication. I decidedhowever to investigate this brightening a bit further,and as I had access to the Faulkes that week,decided to point the 2m scope at this comet, to seeif anything unusual was taking place. The firstimages came in, and I immediately, after loadingthem in to Maxim DL and adjusting the histogram,noticed that a small fuzzy blob appeared to betracking the comet’s movement just behind it. Imeasured the separation as only a few arc-seconds, and after staring at it for a few minutes,decided that it may have fragmented.I contacted Faulkes Telescope control, who put mein touch with the BAA comet section director, whokindly logged this observation the same day. I thencontacted Astronomy Now magazine, who leapt onthe story and images and immediately went topress with it on their website. The following daysthe media furore was quite literally incredible.Interviews with national newspapers, BBC Radio,Coverage on the BBC’s Sky at Night televisionshow, Discovery Channel, Radio Hawaii, Ethiopiawere just a few of the news/media outlets thatpicked up the story.. the news went global that anamateur had made a major astronomical discoveryfrom his desk using a robotic scope. This then ledon to me working with members of the AOP projectwith the NASA/University of Maryland EPOXI


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mission team on imaging and obtaining light curvedata for comet 103P late in 2010, again which ledto articles and images in National Geographic, TheTimes and even my images used by NASA in theirpress briefings, alongside images from the HubbleSpace Telescope. Subscription requests toFaulkes Telescope Project as a result of mydiscoveries went up by hundreds of % from all overthe world.In summaryRobotic telescopes can be fun, they can lead toamazing things, this past year, a work experiencestudent I was mentor for with the FaulkesTelescope Project, imaged several fields we’dassigned to her, where our team then founddozens of new and un-catalogued asteroids, andshe also managed to image a comet fragmenting.Taking pretty pictures is fun, but the buzz for mecomes with the real scientific research I am nowengaged in, and it’s a pathway I aim to stay onprobably for the rest of my astronomical lifetime.For students and people who don’t have the abilityto either own a telescope due to financial orpossibly location constraints, it’s a fantastic way todo real astronomy, using real equipment, and Ihope, in reading this, you’re encouraged to givethese fantastic robotic telescopes a try.

(Source: Universe Today/Nick Howes)

NGC 6302 taken by Thomas Mills High School with the Faulkes Telescope

Comet C/2007 Q3 (Faulkes Telescope) Credit: Nick Howes

The LT open at sunset. Credit: Liverpool Telescope/A. Gomboc


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to set any location, date and time. The imagebelow shows that the program has been set forJune 20, 2004 and the "Dial Time" is set to 12:00pm. To accomplish this, the "Pinawa Central" timewas entered as 12:00 pm and then the "End" keywas selected to freeze the screen. As long as the"End" key is not selected again the "PinawaCentral" time can be adjusted to any time and theclock will remain frozen. Note that the time for"Solar Noon" is given as 12:25:12 pm. Enteringthis time will set the "Dial Time" to 12:00 pm. Notethe following: The time for "Sunrise" is approximately

4:20 am. This is clock time. To get solartime or local apparent time, the "TotalCorrection" must be added. In this casethe correction is approximately -25minutes. Therefore, the earliest time ofsunrise is 3:55 am.

The time for "Sunset" is approximately8:30 pm. Carrying out the same correctionprocedure, the latest time of sunset is 8:05pm.

The azimuth of the sun is 0° indicating thatit is due south.

It is a little more work to obtain the latest morningand earliest afternoon hours. The latest morninghour is when the sun is due east or when theazimuth indicated on the screen below indicates90° E. The earliest afternoon hour is when the sunis due west or when the azimuth indicated on thescreen below indicates 90° W. The way todetermine this is to change the time until each ofthese values is approached. Don't forget to applythe correction as discussed above to obtain solartime. This is easily done by recording the "DIALTIME". You need not be overly accurate as thehour lines on the dial will extend beyond thesepoints. It doesn't take a lot of time to do this.Once you have established the morning andafternoon ranges for the hour lines, you can designyour sundial. Table 1 and Table 2 shows thecalculation performed for a sundial (north/south)located at latitude 50°N. Notice that the hour lineangles for the am and pm hours are symmetricalabout the noon hour line. The issue resourcesincludes a spreadsheet that will perform thesecalculations for you. This spreadsheet is the sameone that is used to design a vertical direct southsundial.When you have determined how large a dial plateyou want then you must give some considerationto how large the gnomon should be. The height ofthe gnomon will determine the path the shadow willtake over the dial plate throughout the year.

Note: For more stuff visit: www.mysundial.ca

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DefinitionsVertical Sundial: any dial in which the dial plate isvertical.Latitude: is the angular position of a place north orsouth of the equator. Positive values in theNorthern hemisphere, negative in the Southernhemisphere.Style Height/Style Angle (SH): of a polar style isthe angle that the style makes with the sub-styleline.Sub-Style (line): the line lying in the dial planewhich is perpendicularly below (or behind for avertical dial) the style.Hour Line: the line on a dial plate indicating theshadow position at a particular time (includesfractional as well as whole hours).Hour Angle (h, HA): the angle corresponding to thesun's position around its daily (apparent) orbit.Measured westward from local noon, it increasesat a rate of 15° per hour. Thus 3 pm (LocalApparent Time) is 45° and 9 am is -45°Hour Line Angle (X, HLA): the angle that an hourline on a dial plate makes with the noon line. For avertical dial, the angle increases counter-clockwise.Azimuth (A, AZ): the angle of the sun, measured inthe horizontal plane and from true south. Angles tothe west are positive, those to east, negative. Thusdue west is 90°, north is ±180°, east is -90°.The vertical sundial must be designed for theparticular latitude (ø) where it is to be used. Thestyle height (SH) of gnomon is equal to the co-latitude or 90° minus the latitude. The hour lineangles (X, HLA) can be calculated as follows:

X = arctan {cos ø * tan (h)}where h is the hour angle, in degrees, given by:

h = (T24 - 12) * 15°and T24 is the time in 24-hour clock notation(hours after midnight) in decimal hours.The sun can only shine on a vertical direct southsundial in the Northern Hemisphere and a verticaldirect north sundial in the Southern Hemispherebetween 6 A.M. and 6 P.M.The sun will only shine on a vertical direct northsundial early in the morning and late in theafternoon. This will occur only in the spring andsummer months and not at all in the fall and winter.The maximum number of hours that can beindicated on a vertical direct north sundial willoccur on the summer solstice, June 20 or 21. Inthe morning this period will be from sunrise untilthe sun is due east and in the afternoon this periodwill be from when the sun is due west until sunset."The Dialist's Companion" can be used todetermine the periods of time that the sun shineson a direct north sundial. This program allows you


Table 1. Hour Line Angle Calculations for direct north sundial.

Table 2. Hour Line Angle Calculations for direct south sundial.

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Figure 1: Vertical Direct North Sundial. This is a plot of the hour lines for a vertical direct north sundial in 15-minute intervals. A drawing like this can beused as a template to lay out a dial plate. It also shows the dial mounting data

Figure 2: Vertical Direct South Sundial. This is a plot of the hour lines for a vertical direct south sundial in 15-minute intervals. A drawing like this can beused as a template to lay out a dial plate. It also shows the dial mounting details.


The following three figures illustrate this for three gnomon heights using a dial plate that is fixed in size. Asthe gnomon height increase the shadow covers more of the plate yet remains on the dial plate. For a verylarge gnomon the shadow will extend beyond the end of the dial plate for portion of the year. The sundialsoftware package "SHADOWS" generates sundial layouts very quickly and is very good for doing this typeof design comparison.

Figure 3: Vertical sundial with gnomon 5 units high .

Figure 4: Vertical sundial with gnomon 15 units high.

Figure 5: Vertical sundial with gnomon 25 units high.

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William Lassel's double image micrometer?

length, and the distance p to s, 9". The micrometerpictured in the introduction is 7"1/4 overall length.Fig. 1 shows a geometric ray first-order ray traceyields the following optical configuration:

the object on the left @ x=3.62, y=-0.1 depicts theimage formed by the refractor's object glass. Thefour lenses, p,q,r,s, are spaced in correctproportion. Airy's original and modified constructionemployed a weak equi-convex positive divided-lens, q. The four lens achromatic eyepiece is anerecting eyepiece. The first lens, p, wasinterchangeable, and spaced such that, a = p.Shorter focal length first lenses provided highermagnification. Airy states in his 1840 report [6] thatwith the lowest power first lens the widestmeasurable separation was ~90"arc.

Separating the divided lens produced elliptical Airydiscs, and prismatic dispersion, but it wastolerable, and accurate separation measures couldbe obtained. However the lens division produced abright diffraction spike perpendicular to thedirection of division, and this made positionmeasures awkward. To enable the zero of theposition angle to be more readily estimated, a wirewas placed in the eye-glass tube at the cross overpoint. However, although Airy makes no mention ofit, the eye lens, s, being a simple positive lens, theimage of the wire would have been marred by falsecolour.

Notice also the similarity of the exit beam angleand the beam angle between the first two lenses, p& q. The exit beam is not much steeper, implyingthe eye lens had a low magnifying power. This inturn meant that a given translation of the dividedlens by the micrometer screw, would produce abarely noticeable separation of the star beingmeasured. Airy confirms this to be so, by stating afaster than normal screw was needed. In otherwords instead of a standard 100tpi (1/100" pitch)screw, a pitch of 40tpi or 50tpi was used. Neither

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IntroductionA mid C19th example of a double imagemicrometer manufactured by Troughton & Simms,has been subject to optical analysis, andcompared to descriptions of similarcontemporaneous micrometers made by the samecompany. Certain features of this particularmicrometer indicate it is unique, and was made forWilliam Lassell in 1858.HistoryThe first four lens eyepiece divided-lens doubleimage micrometer was made by Troughton &Simms for the Royal Greenwich Observatory in1838 [1]. It was designed from first principles byGeorge Airy, based on his analysis of the four-lensachromatic eyepiece [2] and its sphericalcorrection [3]. Airy later published details of amodified four lens micrometer eyepiece in May1845 [4,5].Airy's approach was based on what is now termedfirst order abaxial ray tracing. However rather thanget bogged down in trigonometry, which wouldhave entailed tedious calculation in the days oflogarithm and trigonometry tables, he derivedalgebraic expressions for the crossing points andspacings and surface radii of the four lenses.In his 1845 paper [5] he summarised the lensspacing expressions for chromatic and sphericalcorrection in the following terms. Putting p,q,r,s, asthe focal lengths of the four lenses, ordered fromthe telescope objective, and a,b,c, their respectivespacings, the algebraic expressions were:

0 = bc - cq -(b+c)r - bs + qr + qs + rsin which the lateral translation of the divided lensintroduces no longitudinal chromatic aberration

0 = 3bc - 2(b+c)r-2bs+rsin which the lateral translation of the divided lensproduces no lateral chromatic aberrationwhich when combined produce:

0 = 2bc - bs - (b+c)r + q(c - r - s)Airy had William Simms manufacture his newdesign using the following lens prescription:p, the focal length of the first lens, is arbitrary. (I estimate itwould have been about 2")a, the distance from the first lens to the second, is to be thesame as p.q, the focal length of the second or divided lens, = 5.b, the distance from the second lens to the third, = 2.r, the focal length of the third lens, or field-glass, = 1.c, the distance from the third lens to the fourth, = 7/4.s, the focal length of the fourth lens, or eye-glass, = 1.

The power of the four lens eyepiece is equivalentto that of a single lens 4p/5 focal length. Thevalues are proportions that may be scaled, towhich any unit of length may be applied, but inpractice Simms used the imperial inch. In practicethe original micrometer was about 20" overall


Fig. 1

Fig. 2

Fig. 3

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different forms of solution. One form, whichappeared generally convenient, was indicated inthe memoir, and it has been found in practice to beperfectly successful as regards the special objectof the theory, and to be subject only to two smallpractical inconveniences; that the field is rathercontracted, and that a rather rapid screw isrequired for the micrometer, by which one-half ofthe divided lens is made to slide past the other.The President then stated that he had received acommunication from Mr. Valz, of Marseilles, inwhich that gentleman had pointed out to him thatthe equations might be satisfied in a form whichwould give a larger field of view, by using for thedivided glass a concave lens; and the Presidentstated that he had immediately perceived that theconstruction would possess these two furtheradvantages, that a slower screw would suffice, andthat, in consequence of the thinness of the lensnear the middle, very little light would be lost if thepencils of light were somewhat inclined to the axisof the telescope (the effect of the central thicknessof a convex lens being that, if the pencils are at allinclined, a large proportion of the light is lost, moreespecially for the high magnifying powers.)"Troughton and Simms constructed a micrometer toValz's new design using the following lensprescription:p, the focal length of the first lens, is arbitrary.a, the distance from the first lens to the second, is to be thesame as p.q, the focal length of the second or divided lens, = -1.b, the distance from the second lens to the third, = 1.r, the focal length of the third lens, or field-glass, = 1.c, the distance from the third lens to the fourth, = 3.s, the focal length of the fourth lens, or eye-glass, = 1.

Fig. 4 shows a geometric ray first-order ray traceyields the following optical configuration:An example of a Troughton & Simms divided-lensdouble image micrometer constructed according toValz's arrangement is held in the collection of theMuseum for the History of Science, Oxford.Again, as in Airy's arrangement the position wirewould have been marred by false colour. ButValz's idea of using an equi-concave, instead of anequi-convex lens was a good one, inasmuch asnot only did it widen the apparent field of view forany particular power of first lens, it also flattenedthe field somewhat, making the screw constant,almost uniform across the semi-field. This defectwas unrecognised by Airy, but pointed out byProfessor Frederik Kaiser, of the LeidenObservatory [9].The problem of elliptical Airy discs resulting fromthe divided lens segments was addressed in 1858[10], quote:"The Rev. Mr. Dawes having at the last meetingmade a communication containing some sugges-

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Airy or Simms specifies the screw pitch, butexamining similar micrometers, it appears a screwpitch of 40tpi was adopted.Simms also supplied James Challis with a similarmicrometer for the Northumberland refractor [7].Fig. 2 is a longitudinal section of the 4 lens divided-lens eyepiece. Conveniently the engraver includedan inch scale, from which the lens spacings maybe measured, with the following results:a, the distance from the first lens to the second, isto be the same as p = 47/32"b, the distance from the second lens to the third, =190/32".c, the distance from the third lens to the fourth, =95/32".This is not the same as Airy's prescription. Airy'sdesign has the ratio b/c = 8/7. Simms prescriptionfor Challis' 4 lens divided-lens eyepiece has theratio b/c = 190/95 = 2This gives a value b = 3.5 instead of b = 2, and thesum 2bc - bs - (b+c)r + q(c - r - s) = 2.25. Onlywhen q = 14 does the sum = 0. Perhaps Simmsdecided to use a very weak second lens, but by sodoing image separation would have required a fastscrew, and the range would be restricted. Thereason Simms may have decided upon a muchweaker second lens would be to reduce the loss oflight to the duplicated image when the lenssegments were separated.Given the accuracy of the engraving, and the factthat a scale was included so the reader coulddetermine the physical dimensions, it does notseem likely that the departure from Airy'sprescription can be attributed to artist's licence.Fig.3 is a cross section of the screw box, showingthe divided lens, and the micrometer screw. Theengraver has gone to the trouble of drawing thescrew threads, which have a steep lead angle,indicative of a fast screw.At the meeting of the Royal Astronomical Societyon May 10, 1850, the President, Captain WilliamHenry Smyth, related of a further development ofthe eyepiece micrometer [8], quote:"At the meeting of May 10, the President gave anoral account of a new arrangement of the double-image micrometer. Referring to a paper in theMemoirs of the Society, in which the generalstructure of the four-glass eye-piece, with thesecond lens (reckoning from the object-glass)divided, is described, and in which the equations ofachromaticity are investigated, he showed thatthree equations only are given between sevenquantities (namely, the four focal lengths of thelenses and the three intervals between them), andtherefore, that any four of the quantities may beassumed. The circumstance permits an infinity of


The micrometer has however a fast screw (40tpi) and a drum dividedaccordingly.

It too was also made to Valz's arrangement, butjudging from the length of the revolutions scale,possessed a fast 40tpi screw, although the readingdrum is similar to the Lassell micrometer. TheLeiden micrometer does not possess aperturestops. The focal lengths of the four front lenses,are 1", 3/4", 1/2" & 1/3".

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tions relative to the obtaining better angles ofposition than have hitherto procured with thedivided eye-glass double-image micrometer, andas I was engaged at the time upon the constructionof one for Mr. Lassell, I have been induced to givesome attention to the subject.It will be remembered that the Astronomer Royal,when explaining his construction of the instrument,mentioned the difficulty of obtaining good angles ofposition on account of the elliptic images causedby the transmission of the pencil of rays throughsegments of circles; but that distances weremeasurable with extreme accuracy, the form of thestar being favourable to this observation.A suggestion having been made at the meetingthat Mr. Dawes' plan of fixing, in front of the object-glass, a cap with two circular apertures in contact,might possibly be improved upon; it occurred tome, that the desired improvement would beeffected if stops, with circular apertures of suitablediameters, and with their circumference just incontact, the point of contact being over the divisionof the concave lens, were made to slide into themicrometer itself, as near as practicable to thepoint where the rays cross to form the image.*Upon trial, this was found to answer, the form ofthe star being decidedly improved, but of coursewith the samesacrifice of light as in Mr. Dawes' contrivance. Withplanets, and other faint objects. I believe therewould be no advantage gained in employing thestops, but the manner in which they may beremoved, or changed, I consider to be much moreconvenient than any other method of producing thesame effect.In the instrument made for Mr. Lassell, there arefour stops to accompany the four first lenses,numbered from 1 to 4, but any one can be usedwith any other lens, a smaller aperture stop beingequivalent to cutting off some of the outer edge ofthe speculum or object-glass."* Mr. De la Rue, in an instrument constructed for him, hadshutters to slide at the place, to regulate the brightness of oneof the images.

I have found an example of a similar instrument asSimms described at the Museum for the History ofScience, Oxford (see the images at right).However, this micrometer also has the samereading drum as the previous example, and only 3stops, plus a filter wedge.The particular micrometer William Simmsdescribed, as possessing four first lenses, and fouraperture stops, made for William Lassell in 1858, issimilar to that made for the Leiden Observatory in1858, and used for the 1874 Venus Transit [11].(transits.mhs.ox.ac.uk/browse/onerecord.php?object_id=404).


The first lenses are numbered 1 thru' 4, as are the stops.

Front lenses numbered 1 thru' 4 & one without a number (designated '0').

ratios r=s=1, q=-1, b=3.5, c=0.8. The equation 2bc- bs - (b+c)r + q(c-r-s) = -1. Bearing in mind thesubstitute lenses r & s are achromatic andtherefore corrected for longitudinal chromatic andspherical aberration, the only aberration that isunder-corrected according to Airy's formula islateral chromatic aberration. The stops mask thisto a large extent.This particular micrometer has a 100 tpi screw and40 revolutions travel (20 revolutions either side ofthe zero point). Note the drum head is the same asthat on the Leiden micrometer. The four frontlenses have focal lengths, #4 - 3/4", #3 - 5/8", #2 -13/32", #1 - 9/32". There is also an unnumberedfront lens for use when the eyepiece is used toobserve either the planets, or to measure exit pupildiameters as a dynameter eyepiece, #0 - 1"3/32focal length, and a '0' open stop to match. Thefocal length of the whole eyepiece is equivalent to9/16 times their focal length. From calibrationmeasures, first lens amplifications were found tobe, #0 - A=X1·004, #4 - A=X1·435, #3 - A=X1·621,#2 - A=X2·561, #1 - A = X4·048. From which A xp(inches) = 1·075. With the unmarked first lensseparations up to 120"arc maybe measured.Fig. 5-9 show a geometric ray first-order ray traceyields the following optical configuration:Because the first lens is always placed at its focallength from the second lens, the virtual imageformed by the first lens always lies in the sameplace, x=6.12, y=0.94. The relationship between

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Properties of the Lassel MicrometerWhat makes the Lassell micrometer unique, is thefour insertable aperture stops plus four first lenses.The micrometer matching William Simms'description exactly and depicted below has beenanalysed for its optical arrangement, and found tobe identical to Simms' modification to the originalValz arrangement, as described by him in 1858[10].The eyepiece has been modified by substituting aSymmetrical achromatic eye piece for the last twolenses (r & s), and the lens spacing adjusted asfollows:p, the focal length of the first lens, is arbitrary.a, the distance from the first lens to the second, is to be thesame as p.q, the focal length of the second or divided lens, = -1.b, the distance from the second lens to the third, = 3·5.r, the focal length of the third lens, or field-glass, = 1.c, the distance from the third lens to the fourth, = 1.s, the focal length of the fourth lens, or eye-glass, = 1.

The spacing between the second and third lenshas been increased, and the eye-glass tubemodified to accommodate the position wire. In sodoing the Symmetrical achromatic eyepiece maybe placed with its field lens (the third lens) behindthe position wire, and higher powers achieved witha wider field of view.In practice, to provide eye relief, c is reduced from1 to 0·8, which introduces an acceptable modicumof lateral chromatic aberration. The advantage ofthis arrangement is that the position wire (there area pair of parallel wires narrowly separated in thisinstance) is not marred by false colour.Table 1 shows the three prescriptions discussedand Lord's modification to Valz's prescription:

Table 1.

The focal length of the divided lens q is -0"·81, theachromatic field and eye lenses r & s, 0"·832,separation c, 0"·63 and the separation of thedivided lens and field lens b, 2"·875, which gives


Fig. 4.

Fig. 5. First lens #0 - geometric ray thin lens ray trace - object @ x=1.41, y=-0.2 is image formed by object glass.


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Divided-lens & micrometer screw drum - the drum is divided into 100divs.

'0' stop in front of divided-lens.

Micrometer screw revolutions scale 0 - 40 revs travel- the zero point is at20.

Divided concave lens.

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the object position and the first lens focal lengthmay be calculated from the standard thin lensequation 1/p = 1/u + 1/v, where u & v are theobject & image distances.The relationship between the first lensamplification of the eyepiece is not sostraightforward. It is given by the ratio of the firstlens magnification divided by the Barlowedmagnification of the second lens, divided by aconstant. The constant is governed by the effectivefocal length of the eyepiece section lenses r & s, &second lens q. Let the efl of r & s = w, then the eflof r,s & q will be qw/q+w-(b+c), where w = rs/r+s-cThe first lens magnification is its image distancedivided by its object distance. Since the virtualimage of the first lens always lies in the sameplace with respect to the second lens, its imagedistance is equal to the first lens focal length plusthe distance between the second lens and thevirtual image of the first lens.Table 2 shows the spreadsheet calculations:

Table 2 (all length units are inches).

The amplification factors A are derived bycalibration on known pairs (see section Micrometerin Use below). The first lens magnification is givenby m=v/u. The constant k=Z/B is that derived fromthe calibrated amplifications, k calc is thetheoretical value. The deviation from the calibratedvalues are due to inaccuracies in calibrating thefirst lens focal lengths, and the eyepiece lenses r &s, and the negative focal length of the second lensq, plus build error. In theory pA=1", hence the firstlens amplification is the reciprocal of its focallength in inches (truly an imperial design!).The linear image displacement (LID) produced bya single rotation of the micrometer screw is thescrew pitch divided by the amplification factor ofthe first lens, equating to: first lens '0' LID 0".00996 first lens '4' LID 0".00697 first lens '3' LID 0".00617 first lens '2' LID 0".00390 first lens '1' LID 0".00247

The angular image displacement caused by asingle rotation of the micrometer screw iscalculated from R=(648000/pi X 0".01/F)/A, whichfor a 100" focal length object glass is20".6265arc/A, and since A=1.075/ p,R=(649000/pi X 0".01/F)Xp/1.075.


Eenlargement of the four stops.

loss of light from one component. Taking a specificinstance, #2 first lens & '2' stop, intended for10"arc pairs, it would not be feasible to measure a14"arc pair because one of the pair would beocculted. One would perforce switch to the #4 firstlens & '1' stop.There are 20 possible combinations of doubleimage stops and first lenses covering a range from62"arc to 5"arc. In practice I found the #1 first lensand the #1 stop unusable, the image was marredby intrusive diffraction, and the prismaticdispersion objectionable. Given this practicallimitation consider the separations that could havebeen measured with the aid of Table 4. Stop '1' &first lens #1 are impractical, so the range ofmeasurable separations are reduced to those inTable 5.The range in separations each stop couldaccommodate would depend on the size of theAiry disc, which at f/15 would be 0".0004 in yellowlight (0.04 revs or 4 drum divs). For a double starwith components of equal magnitude, a realisticleeway for each stop would be approximately ±4Airy disc diameters which equates to 0.16 revs, &converted to arc for F=100": '4' ±2".3arc; '3'±2".0arc; '2' ±1".3arc; '1' ±0".82The separation ranges each combination of firstlenses and stops can cover is plotted in bar Chart1. The separation limits are 4".28arc to 63".93arc.The grey shaded columns are separationsmeasurable using the #1 first lens &/or '1' stop, orunmeasurable with any combination. It is evidentthere are separations that could not be measuredusing these stops. A shortcoming Simms in alllikelihood did not envisage.I can find no record of double star measureshaving been made using these double imagestops. Simms mentions Warren De la Rue and

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The stops are numbered '0', '1', '2', '3', '4'. Stops 1,2, 3 & 4 are pairs of holes, touching, just as Simmsdescribed, varying in size and separation. The '0'stop is a plain hole, intended to be used with themicrometer when measuring planet or exit pupildiameters. The '0' stop hole is 40 drill gauge or 98thou, the '4' stop 70 drill gauge or 28 thou, '3' stop74 drill gauge or 22·5 thou, '2' stop 80 drill gaugeor 13·5 thou, '1' stop micro drill gauge 93 or 7·5thou.The '0' stop covers 9.8 revolutions of themicrometer screw. The '4' stop holes areseparated by 30thou (3 revs), the '3' stop 20thou (2revs), the '2' stop 13thou (1.3 revs), the '1' stop10thou (1 rev). Given the linear displacement is thescrew pitch divided by the amplification factor ofthe first lens, the smallest linear separation of adouble star ('1' stop & #1 first lens) would be0".00247. For a 100" focal length object glass thiscorresponds to an angular separation of 5".1arc.The widest separation ('4' stop & #4 first lens) 43".1arc. With the '0' stop in theory the widestseparation would be ('0' stop & #0 first lens)200"arc, but prismatic dispersion limits it to about120"arc. The implication being, whereasseparations could be measured to a greateraccuracy than a filar micrometer, doubles close tothe resolution limit of the objective were outside itsrange.Bear in mind the '0' stop is a 98thou circularaperture, that enables pairs across the range to bemeasured. Using first lens #3 one drum divisionwould equate to 1".25arc. Screw backlash makes itawkward to make such fine measures, although inpractice I was able to obtain accuracies less than±0".2arc on bright proximate pairs.The actual spread in values is given in Table 3. LIDis in inches, angular displacement in arcsecs.

Table 3.

Simms clearly states any stop may be used withany first lens (10), but the idea of using stops tomake the elliptical images round, leads to aquantisation effect. The calibrations I carried outwere done using the '0' stop only. I don't believe itwould be feasible to calibrate each first lens usingthe double image stops. The shorter focal lengthfirst lenses also introduce greater prismaticdispersion for a given lens translation, and thesmaller stops cause greater loss of light, so it isbetter to use a lower power first lens and a widerstop where feasible. There would be a small rangeeither side of the image displacement value thestop could accommodate, but there would be a


Table 4.

Table 5.

Chart 1.

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William Rutter Dawes having used his divided lensmicrometer but their micrometers were not fittedwith these stops. I found it simpler to tolerate theelliptical Airy discs and use either no stop or the '0'stop.The Micrometer In UseOne of the reasons this type of micrometer was notas popular as a filar micrometer is becausecalibration is a tedious process. This micrometerhas in total five first or relay lenses, so there arefive screw constants to calibrate. Airy had hisprinciple observer, Robert Main, calibrate the RGOmicrometer using timings of wide pairs. Themethod I adopted entailed taking double distancemeasures of known pairs over many nights.Calibrated five screw constants and the amplifyingpower of the relay lenses:'0' lens A=X1.004 R = 19".5625±0".4353'4' lens A=X1.435 R = 13".6886±0".2073'3' lens A=X1.621 R = 12".1184±0".2532'2' lens A=X2.561 R = 7".6716±0".2382'1' lens A=X4.048 R = 4".8523±0".1304

from which by linear regression R = 19".64/A +0".002 correlation coefficient = 0.999 999 994 i.e.R = 19".64/A.Once the screw constants have been determinedseparation measures are just as easy to reduce aswith a filar micrometer. The pair of stars and theirdouble images are either strung out equidistant inline, or as a rhomb, and double distance measurestaken to eliminate zero point error.e.g.28APR95 SEEING: II_III#3 lens stop '0' R = 12".1184±0".2532alpha GEM rho' = 3".48 (catalogue)2i = 2043 - 1983 = 602i = 2042.5 - 1985 = 57.52i = 2043 - 1989 = 542i = 2041 - 19089 = 522i = 2041 -1987 = 54rho = 3".363±0".131 (probable error)gamma LEO rho' = 4".40 (catalogue)2i = 2051 - 1981 = 702i = 2050 - 1986 = 642i = 2053 - 1982 = 71rho = 4".14±0".155 (probable error)

separation measures that are within acceptablelimits of accuracy, comparable to a filarmicrometer.The field of view stopped down is too narrow toreadily find and centre a double star, the stop mustbe withdrawn, the double centred, and broughtonto the division using the tilt screw, and then thestop inserted.ConclusionThe Troughton & Simms divided-lens doubleimage micrometer was similarly priced to their filarmicrometer. In his book, 'The AchromaticTelescope' [12] William Simms includes a trade


The tilt screw is used to bring the image directly onto the division, wherethe image brightness reaches a maximum.

Given the individual orders that Simms would havefulfilled, and their infrequency, and the exactcorrespondence between his description and theexample in question, it is reasonable to surmisethat in all probability it is that made for WilliamLassell, and presumably in his possession until hisdeath in 1880. Its provenance is unknown. It cameinto my possession in 1993, and was restored withthe assistance H.N. Irving & Son.

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catalogue, page 12 of which lists item 285, ParallelWire Position Micrometer at between £8-8s & £15-15s, and item 286, Double Image Micrometer, withPosition Circle, &c, at £16-16s.Simms makes no mention of his double imagemicrometer in his book, but does mention the filarmicrometer, which was far more popular because itwas easier to calibrate.Divided-lens double image micrometers made byTroughton & Simms, surviving in collections ofscientific instruments, are extremely rare. Fewwould have been made, and all to order, and madeas one-offs. Similarities in appearance are owingto manufacturing tradition, not mass production.At a time when the artisans who worked forTroughton & Simms in the mid C19th were paidabout 10s a week, a scientific instrument costing£16-16s, equivalent to 34 weeks wages, wouldhave been unaffordable. There were very fewastronomers who could afford such instruments.Those who could were usually grand amateurs, orprofessional astronomers procuring instruments forprivate or university observatories. The smalldemand for this type of micrometer, and it'srelatively rapid development, meant eachmicrometer made by William Simms, was slightlydifferent from the previous one. Despite extensivesearches I have not come across anotherTroughton & Simms divided-lens double imagemicrometer identical to the one described byWilliam Simms to the RAS in 1858, and stated asbeing that which he was at the time making forWilliam Lassell.

References:[01]. R.G.O. 6/716. 365 Mennim, Eleanor, "Transit Circle, The story of William Simms 1793-1860", ISBN 1850721017. "In

mid-December (1839) he (William Simms) had to admit to Airy (G.B.Airy - Astronomer Royal) that he had lost theestimate for a double image eyepiece and position circle."

[02]. Airy, George Biddell, B.A.,"On the Principles and Construction of the Achromatic Eye-Pieces of Telescopes..." Cambs.Phil. Trans., XIV, Vol. II, pt. II, pp227-252, & Plate XI, read May 17, 1824, written at Trinity College, April 26, 1824, (1827)

[03]. Airy, George Biddell, M.A., "On the Spherical Aberration of Eye-Pieces of Telescopes", Cambs. Phil. Trans., I, Vol. III, Pt.1, pp 1-63, & Plate I, read May 14 and May 21, 1827, (1830)

[04]. Airy, G.B. Esq., Astronomer Royal, "On a new construction of the Divided Eye-glass Double-Image Micrometer". MNRAS,XVI, 16, pp229-231, 1845.

[05]. Airy, G.B. Esq., Astronomer Royal, "On a New Construction of the Divided Eye-Glass Double-Image Micrometer".MNRAS, XVI, pp199-209, read May 9, 1845, written April 22, 1845.

[06]. Airy, G.B. Esq., Astronomer Royal, "Observations of the Distances and Positions of Double Stars and of the Diameters ofPlanets, with a double-image eye-piece attached to the South Equatorial, p172-184". Greenwich Observations, 1840,§13, pp lxv-lxxvii.

[07]. Challis, James, M.A., F.R.S., F.R.A.S., "Lectures on Practical Astronomy and Astronomical Instruments", §320, pp309-313,& Plate IV, figs. 2 & 3, p335, Cambridge, Deighton, Bell and Co., 1879.

[08]. Smyth, William Henry, "Mr. Airy on the divided Eye-piece", MNRAS, X, pp160-161, 1850.[09]. Lohse, J. Gerhard; Copeland, Ralph, "On a New Double Image Micrometer", Annals of the Royal Observatory, Edinburgh,

Vol.1, pp152-198, 1902.[10]. Simms, William, Jr. Esq., "Notice of an Improvement of the Double-Image Position Micrometer", MNRAS, XVIII, p64, 1858.[11]. Oudemans, J.A.C., "On the Condition that in a Double-Image Micrometer the value of a Revolution of the Micrometer

Screw is independent of the Accommodation of the Eye". MNRAS, XLVIII, pp334-335, May 1888.[12]. Simms, William, F.R.S., F.R.A.S, "The Achromatic Telescope and its various mountings especially The Equatorial".

Troughton and Simms, Taylor & Francis, Fleet Street, London, 1852.


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Contest Conic Sections Orbital Elements Types of Orbits Newton's Laws of Motion and Universal

Gravitation Uniform Circular Motion Motions of Planets and Satellites Launch of a Space Vehicle Position in an Elliptical Orbit Orbit Perturbations Orbit Maneuvers The Hyperbolic Orbit

Orbital mechanics, also called flight mechanics, isthe study of the motions of artificial satellites andspace vehicles moving under the influence offorces such as gravity, atmospheric drag, thrust,etc. Orbital mechanics is a modern offshoot ofcelestial mechanics which is the study of themotions of natural celestial bodies such as themoon and planets. The root of orbital mechanicscan be traced back to the 17th century whenmathematician Isaac Newton (1642-1727) putforward his laws of motion and formulated his lawof universal gravitation. The engineeringapplications of orbital mechanics include ascenttrajectories, reentry and landing, rendezvouscomputations, and lunar and interplanetarytrajectories.

Conic SectionsA conic section, or just conic, is a curve formed bypassing a plane through a right circular cone. Asshown in Figure 1, the angular orientation of theplane relative to the cone determines whether theconic section is a circle, ellipse, parabola, orhyerbola. The circle and the ellipse arise when theintersection of cone and plane is a bounded curve.The circle is a special case of the ellipse in whichthe plane is perpendicular to the axis of the cone. Ifthe plane is parallel to a generator line of the cone,the conic is called a parabola. Finally, if theintersection is an unbounded curve and the planeis not parallel to a generator line of the cone, thefigure is a hyperbola. In the latter case the planewill intersect both halves of the cone, producingtwo separate curves.

Orbital mechanics, also called flight mechanics, is the study of the motions of artificial satellites and space vehiclesmoving under the influence of forces such as gravity, atmospheric drag, thrust, etc. Orbital mechanics is a modernoffshoot of celestial mechanics which is the study of the motions of natural celestial bodies such as the moon and planets.The root of orbital mechanics can be traced back to the 17th century when mathematician Isaac Newton (1642-1727) putforward his laws of motion and formulated his law of universal gravitation. The engineering applications of orbitalmechanics include ascent trajectories, reentry and landing, rendezvous computations, and lunar and interplanetarytrajectories…

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Conic Section Eccentricity, e Semi-major axis Energy

Circle 0 = radius < 0

Ellipse 0 < e < 1 > 0 < 0

Parabola 1 infinity 0

Hyperbola > 1 < 0 > 0

We can define all conic sections in terms of theeccentricity. The type of conic section is alsorelated to the semi-major axis and the energy. Thetable below shows the relationships betweeneccentricity, semi-major axis, and energy and thetype of conic section.Satellite orbits can be any of the four conicsections. This page deals mostly with ellipticalorbits, though we conclude with an examination ofthe hyperbolic orbit.Orbital ElementsTo mathematically describe an orbit one mustdefine six quantities, called orbital elements. Theyare: Semi-Major Axis, a Eccentricity, e Inclination, i Argument of Periapsis, Time of Periapsis Passage, T Longitude of Ascending Node,

An orbiting satellite follows an oval shaped pathknown as an ellipse with the body being orbited,called the primary, located at one of two points


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called foci. An ellipse is defined to be a curve withthe following property: for each point on an ellipse,the sum of its distances from two fixed points,called foci, is constant (see Figure 2). The longestand shortest lines that can be drawn through thecenter of an ellipse are called the major axis andminor axis, respectively. The semi-major axis isone-half of the major axis and represents asatellite's mean distance from its primary.Eccentricity is the distance between the focidivided by the length of the major axis and is anumber between zero and one. An eccentricity ofzero indicates a circle.Inclination is the angular distance between asatellite's orbital plane and the equator of itsprimary (or the ecliptic plane in the case ofheliocentric, or sun centered, orbits). An inclinationof zero degrees indicates an orbit about theprimary's equator in the same direction as theprimary's rotation, a direction called prograde (ordirect). An inclination of 90 degrees indicates apolar orbit. An inclination of 180 degrees indicatesa retrograde equatorial orbit. A retrograde orbit isone in which a satellite moves in a directionopposite to the rotation of its primary.Periapsis is the point in an orbit closest to theprimary. The opposite of periapsis, the farthestpoint in an orbit, is called apoapsis. Periapsis andapoapsis are usually modified to apply to the bodybeing orbited, such as perihelion and aphelion forthe Sun, perigee and apogee for Earth, perijoveand apojove for Jupiter, perilune and apolune forthe Moon, etc. The argument of periapsis is theangular distance between the ascending node andthe point of periapsis (see Figure 3). The time ofperiapsis passage is the time in which a satellitemoves through its point of periapsis.Nodes are the points where an orbit crosses aplane, such as a satellite crossing the Earth'sequatorial plane. If the satellite crosses the planegoing from south to north, the node is theascending node; if moving from north to south, it isthe descending node. The longitude of theascending node is the node's celestial longitude.Celestial longitude is analogous to longitude onEarth and is measured in degrees counter-clockwise from zero with zero longitude being inthe direction of the vernal equinox.In general, three observations of an object in orbitare required to calculate the six orbital elements.Two other quantities often used to describe orbitsare period and true anomaly. Period, P, is thelength of time required for a satellite to completeone orbit. True anomaly, , is the angular distanceof a point in an orbit past the point of periapsis,measured in degrees.Types Of OrbitsFor a spacecraft to achieve Earth orbit, It must be

launched to an elevation above the Earth'satmosphere and accelerated to orbital velocity.The most energy efficient orbit, that is one thatrequires the least amount of propellant, is a directlow inclination orbit. To achieve such an orbit, aspacecraft is launched in an eastward directionfrom a site near the Earth's equator. Theadvantage being that the rotational speed of theEarth contributes to the spacecraft's final orbitalspeed. At the United States' launch site in CapeCanaveral (28.5 degrees north latitude) a due eastlaunch results in a "free ride" of 1,471 km/h (914mph). Launching a spacecraft in a direction otherthan east, or from a site far from the equator,results in an orbit of higher inclination. Highinclination orbits are less able to take advantage ofthe initial speed provided by the Earth's rotation,thus the launch vehicle must provide a greaterpart, or all, of the energy required to attain orbitalvelocity. Although high inclination orbits are less


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energy efficient, they do have advantages overequatorial orbits for certain applications. Below wedescribe several types of orbits and theadvantages of each:Geosynchronous orbits (GEO) are circular orbitsaround the Earth having a period of 24 hours. Ageosynchronous orbit with an inclination of zerodegrees is called a geostationary orbit. Aspacecraft in a geostationary orbit appears to hangmotionless above one position on the Earth'sequator. For this reason, they are ideal for sometypes of communication and meteorologicalsatellites. A spacecraft in an inclinedgeosynchronous orbit will appear to follow aregular figure-8 pattern in the sky once every orbit.To attain geosynchronous orbit, a spacecraft is firstlaunched into an elliptical orbit with an apogee of35,786 km (22,236 miles) called a geosynchronoustransfer orbit (GTO). The orbit is then circularizedby firing the spacecraft's engine at apogee.Polar orbits (PO) are orbits with an inclination of90 degrees. Polar orbits are useful for satellitesthat carry out mapping and/or surveillanceoperations because as the planet rotates thespacecraft has access to virtually every point onthe planet's surface.Walking orbits: An orbiting satellite is subjected toa great many gravitational influences. First, planetsare not perfectly spherical and they have slightlyuneven mass distribution. These fluctuations havean effect on a spacecraft's trajectory. Also, the sun,moon, and planets contribute a gravitationalinfluence on an orbiting satellite. With properplanning it is possible to design an orbit whichtakes advantage of these influences to induce aprecession in the satellite's orbital plane. Theresulting orbit is called a walking orbit, orprecessing orbit.Sun synchronous orbits (SSO) are walking orbitswhose orbital plane precesses with the sameperiod as the planet's solar orbit period. In such anorbit, a satellite crosses periapsis at about thesame local time every orbit. This is useful if asatellite is carrying instruments which depend on acertain angle of solar illumination on the planet'ssurface. In order to maintain an exact synchronoustiming, it may be necessary to conduct occasionalpropulsive maneuvers to adjust the orbit.

Molniya orbits are highly eccentric Earth orbitswith periods of approximately 12 hours (2revolutions per day). The orbital inclination ischosen so the rate of change of perigee is zero,thus both apogee and perigee can be maintainedover fixed latitudes. This condition occurs atinclinations of 63.4 degrees and 116.6 degrees.For these orbits the argument of perigee istypically placed in the southern hemisphere, so the

satellite remains above the northern hemispherenear apogee for approximately 11 hours per orbit.This orientation can provide good ground coverageat high northern latitudes.Hohmann transfer orbits are interplanetarytrajectories whose advantage is that they consumethe least possible amount of propellant. AHohmann transfer orbit to an outer planet, such asMars, is achieved by launching a spacecraft andaccelerating it in the direction of Earth's revolutionaround the sun until it breaks free of the Earth'sgravity and reaches a velocity which places it in asun orbit with an aphelion equal to the orbit of theouter planet. Upon reaching its destination, thespacecraft must decelerate so that the planet'sgravity can capture it into a planetary orbit.To send a spacecraft to an inner planet, such asVenus, the spacecraft is launched and acceleratedin the direction opposite of Earth's revolutionaround the sun (i.e. decelerated) until it achieves asun orbit with a perihelion equal to the orbit of theinner planet. It should be noted that the spacecraftcontinues to move in the same direction as Earth,only more slowly.To reach a planet requires that the spacecraft beinserted into an interplanetary trajectory at thecorrect time so that the spacecraft arrives at theplanet's orbit when the planet will be at the pointwhere the spacecraft will intercept it. This task iscomparable to a quarterback "leading" his receiverso that the football and receiver arrive at the samepoint at the same time. The interval of time inwhich a spacecraft must be launched in order tocomplete its mission is called a launch window.

Newton's Laws of Motion and UniversalGravitation

Newton's laws of motion describe the relationshipbetween the motion of a particle and the forcesacting on it.The first law states that if no forces are acting, abody at rest will remain at rest, and a body inmotion will remain in motion in a straight line.Thus, if no forces are acting, the velocity (bothmagnitude and direction) will remain constant.The second law tells us that if a force is appliedthere will be a change in velocity, i.e. anacceleration, proportional to the magnitude of theforce and in the direction in which the force isapplied. This law may be summarized by theequation

where F is the force, m is the mass of the particle,and a is the acceleration.The third law states that if body 1 exerts a force onbody 2, then body 2 will exert a force of equalstrength, but opposite in direction, on body 1. This


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law is commonly stated, "for every action there isan equal and opposite reaction".In his law of universal gravitation, Newton statesthat two particles having masses m1 and m2 andseparated by a distance r are attracted to eachother with equal and opposite forces directed alongthe line joining the particles. The commonmagnitude F of the two forces is

where G is an universal constant, called theconstant of gravitation, and has the value6.67259x10-11 N-m2/kg2 (3.4389x10-8 lb-ft2/slug2).Let's now look at the force that the Earth exerts onan object. If the object has a mass m, and theEarth has mass M, and the object's distance fromthe center of the Earth is r, then the force that theEarth exerts on the object is GmM /r2 . If we dropthe object, the Earth's gravity will cause it toaccelerate toward the center of the Earth. ByNewton's second law (F = ma), this acceleration gmust equal (GmM /r2)/m, or

At the surface of the Earth this acceleration hasthe valve 9.80665 m/s2 (32.174 ft/s2).Many of the upcoming computations will besomewhat simplified if we express the product GMas a constant, which for Earth has the value3.986005x1014 m3/s2 (1.408x1016 ft3/s2). Theproduct GM is often represented by the Greekletter .For additional useful constants please see theappendix Basic Constants.For a refresher on SI versus U.S. units see theappendix Weights & Measures.Uniform Circular MotionIn the simple case of free fall, a particleaccelerates toward the center of the Earth whilemoving in a straight line. The velocity of theparticle changes in magnitude, but not in direction.In the case of uniform circular motion a particlemoves in a circle with constant speed. The velocityof the particle changes continuously in direction,but not in magnitude. From Newton's laws we seethat since the direction of the velocity is changing,there is an acceleration. This acceleration, calledcentripetal acceleration is directed inward towardthe center of the circle and is given by

where v is the speed of the particle and r is theradius of the circle. Every accelerating particlemust have a force acting on it, defined by Newton'ssecond law (F = ma). Thus, a particle undergoing

uniform circular motion is under the influence of aforce, called centripetal force, whose magnitude isgiven by

The direction of F at any instant must be in thedirection of a at the same instant, that is radiallyinward.

A satellite in orbit is acted on only by the forces ofgravity. The inward acceleration which causes thesatellite to move in a circular orbit is thegravitational acceleration caused by the bodyaround which the satellite orbits. Hence, thesatellite's centripetal acceleration is g, that is g =v2/r. From Newton's law of universal gravitation weknow that g = GM /r2. Therefore, by setting theseequations equal to one another we find that, for acircular orbit,

Example Problem 1

PROBLEM 1Calculate the velocity of an artificialsatellite orbiting the Earth in a circularorbit at an altitude of 200 km above theEarth's surface.SOLUTION, From Basics Constants, Radius of Earth = 6,378.140 km GM of Earth = 3.986005×1014 m3/s2 Given: r = (6,378.14 + 200) × 1,000

= 6,578,140 m Equation (6), v = SQRT[ GM / r ] v = SQRT[ 3.986005×1014 / 6,578,140 ] v = 7,784 m/s

Motions of Planets and SatellitesThrough a lifelong study of the motions of bodies inthe solar system, Johannes Kepler (1571-1630)was able to derive three basic laws known asKepler's laws of planetary motion. Using the datacompiled by his mentor Tycho Brahe (1546-1601),Kepler found the following regularities after yearsof laborious calculations: All planets move in elliptical orbits with the

sun at one focus. A line joining any planet to the sun sweeps

out equal areas in equal times. The square of the period of any planet

about the sun is proportional to the cube ofthe planet's mean distance from the sun.


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These laws can be deduced from Newton's laws ofmotion and law of universal gravitation. Indeed,Newton used Kepler's work as basic information inthe formulation of his gravitational theory.As Kepler pointed out, all planets move in ellipticalorbits, however, we can learn much aboutplanetary motion by considering the special caseof circular orbits. We shall neglect the forcesbetween planets, considering only a planet'sinteraction with the sun. These considerationsapply equally well to the motion of a satellite abouta planet.Let's examine the case of two bodies of masses Mand m moving in circular orbits under the influenceof each other's gravitational attraction. The centerof mass of this system of two bodies lies along theline joining them at a point C such that mr = MR.The large body of mass M moves in an orbit ofconstant radius R and the small body of mass m inan orbit of constant radius r, both having the sameangular velocity . For this to happen, thegravitational force acting on each body mustprovide the necessary centripetal acceleration.Since these gravitational forces are a simpleaction-reaction pair, the centripetal forces must beequal but opposite in direction. That is, m 2r mustequal M 2R. The specific requirement, then, isthat the gravitational force acting on either bodymust equal the centripetal force needed to keep itmoving in its circular orbit, that is

If one body has a much greater mass than theother, as is the case of the sun and a planet or theEarth and a satellite, its distance from the center ofmass is much smaller than that of the other body.If we assume that m is negligible compared to M,then R is negligible compared to r. Thus, equation(7) then becomes

If we express the angular velocity in terms of theperiod of revolution, = 2 /P, we obtain

where P is the period of revolution. This is a basicequation of planetary and satellite motion. It alsoholds for elliptical orbits if we define r to be thesemi-major axis (a) of the orbit.A significant consequence of this equation is that itpredicts Kepler's third law of planetary motion, thatis P2~r3.

Example Problem 2

PROBLEM 2Calculate the period of revolution for thesatellite in PROBLEM 1.SOLUTION, Given: r = 6,578,140 m Equation (9), P2 = 4× 2×r3/GM P = SQRT[4× 2×r3/GM] P = SQRT[4× 2×6,578,1403/3.986005×1014] P = 5,310 s

Example Problem 3

PROBLEM 3Calculate the radius of orbit for a Earthsatellite in a geosynchronous orbit, where theEarth's rotational period is 86,164.1 seconds.SOLUTION, Given: P = 86,164.1 s Equation (9), P2 = 4× 2×r3/GM r = [P2×GM/(4× 2)]1/3 r = [86,164.12×3.986005×1014/(4× 2)]1/3 r = 42,164,170 m

In celestial mechanics where we are dealing withplanetary or stellar sized bodies, it is often thecase that the mass of the secondary body issignificant in relation to the mass of the primary, aswith the Moon and Earth. In this case the size ofthe secondary cannot be ignored. The distance Ris no longer negligible compared to r and,therefore, must be carried through the derivation.Equation (9) becomes

More commonly the equation is written in theequivalent form


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where a is the semi-major axis. The semi-majoraxis used in astronomy is always the primary-to-secondary distance, or the geocentric semi-majoraxis. For example, the Moon's mean geocentricdistance from Earth (a) is 384,403 kilometers. Onthe other hand, the Moon's distance from thebarycenter (r) is 379,732 km, with Earth's counter-orbit (R) taking up the difference of 4,671 km.Kepler's second law of planetary motion must, ofcourse, hold true for circular orbits. In such orbitsboth and r are constant so that equal areas areswept out in equal times by the line joining a planetand the sun. For elliptical orbits, however, bothand r will vary with time. Let's now consider thiscase.Figure 5 shows a particle revolving around C alongsome arbitrary path. The area swept out by theradius vector in a short time interval t is shownshaded. This area, neglecting the small triangularregion at the end, is one-half the base times theheight or approximately r(r t)/2. This expressionbecomes more exact as t approaches zero, i.e.the small triangle goes to zero more rapidly thanthe large one. The rate at which area is beingswept out instantaneously is therefore

For any given body moving under the influence ofa central force, the value r2 is constant.Let's now consider two points P1 and P2 in an orbitwith radii r1 and r2, and velocities v1 and v2. Sincethe velocity is always tangent to the path, it can beseen that if is the angle between r and v, then

where vsin is the transverse component of v.Multiplying through by r, we have

or, for two points P1 and P2 on the orbital path

Note that at periapsis and apoapsis, = 90degrees. Thus, letting P1 and P2 be these twopoints we get

Let's now look at the energy of the above particleat points P1 and P2. Conservation of energy statesthat the sum of the kinetic energy and the potentialenergy of a particle remains constant. The kineticenergy T of a particle is given by mv2/2 while thepotential energy of gravity V is calculated by theequation -GMm/r. Applying conservation of energywe have


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From equations (14) and (15) we obtain

Rearranging terms we get

Example Problem 4

PROBLEM 4An artificial Earth satellite is in anelliptical orbit which brings it to an altitudeof 250 km at perigee and out to an altitude of500 km at apogee. Calculate the velocity ofthe satellite at both perigee and apogee.SOLUTION, Given: Rp = (6,378.14 + 250) × 1,000

= 6,628,140 m Ra = (6,378.14 + 500) × 1,000

= 6,878,140 m Equations (16) and (17), Vp = SQRT[2×GM×Ra/(Rp×(Ra+Rp))] Vp = SQRT[2×3.986005×1014×6,878,140/

(6,628,140×(6,878,140+6,628,140))] Vp = 7,826 m/s Va = SQRT[2×GM×Rp/(Ra×(Ra+Rp))] Va = SQRT[2×3.986005×1014×6,628,140/

(6,878,140×(6,878,140+6,628,140))] Va = 7,542 m/s

Example Problem 5

PROBLEM 5A satellite in Earth orbit passes through itsperigee point at an altitude of 200 km abovethe Earth's surface and at a velocity of 7,850m/s. Calculate the apogee altitude of thesatellite.SOLUTION,Given: Rp = (6,378.14 + 200) × 1,000

= 6,578,140 m Vp = 7,850 m/s

Equation (18), Ra = Rp/[2×GM/(Rp×Vp2)-1] Ra = 6,578,140/[2×3.986005×1014/

(6,578,140×7,8502)-1] Ra = 6,805,140 m

Altitude @ apogee = 6,805,140/1,000-6,378.14= 427.0 km

The eccentricity e of an orbit is given by

Example Problem 6

PROBLEM 6Calculate the eccentricity of the orbit for thesatellite in PROBLEM 5.SOLUTION, Given: Rp = 6,578,140 m Vp = 7,850 m/s

Equation (20), e = Rp × Vp2 / GM - 1

e = 6,578,140 × 7,8502 / 3.986005×1014 - 1e = 0.01696

If the semi-major axis a and the eccentricity e of anorbit are known, then the periapsis and apoapsisdistances can be calculated by

Example Problem 7

PROBLEM 7A satellite in Earth orbit has a semi-majoraxis of 6,700 km and an eccentricity of 0.01.Calculate the satellite's altitude at bothperigee and apogee.SOLUTION, Given: a = 6,700 km e = 0.01 Equation (21) and (22), Rp = a × (1 - e) Rp = 6,700 × (1 - .01) Rp = 6,633 km Altitude @ perigee = 6,633 - 6,378.14

= 254.9 km Ra = a × (1 + e) Ra = 6,700 × (1 + .01) Ra = 6,767 kmAltitude @ apogee = 6,767 - 6,378.14 = 388.9 km

Launch of a Space VehicleThe launch of a satellite or space vehicle consistsof a period of powered flight during which thevehicle is lifted above the Earth's atmosphere andaccelerated to orbital velocity by a rocket, orlaunch vehicle. Powered flight concludes at burn-


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out of the rocket's last stage at which time thevehicle begins its free flight. During free flight thespace vehicle is assumed to be subjected only tothe gravitational pull of the Earth. If the vehiclemoves far from the Earth, its trajectory may beaffected by the gravitational influence of the sun,moon, or another planet.A space vehicle's orbit may be determined fromthe position and the velocity of the vehicle at thebeginning of its free flight. A vehicle's position andvelocity can be described by the variables r, v, and

, where r is the vehicle's distance from the centerof the Earth, v is its velocity, and is the anglebetween the position and the velocity vectors,called the zenith angle (see Figure 7). If we let r1,v1, and 1 be the initial (launch) values of r, v, and

, then we may consider these as given quantities.If we let point P2 represent the perigee, thenequation (13) becomes

Substituting equation (23) into (15), we can obtainan equation for the perigee radius Rp.

Multiplying through by -Rp2/(r1

2v12) and rearranging,

we get

Note that this is a simple quadratic equation in theratio (Rp/r1) and that 2GM /(r1 × v1

2) is anondimensional parameter of the orbit.Solving for (Rp/r1) gives

Like any quadratic, the above equation yields twoanswers. The smaller of the two answerscorresponds to Rp, the periapsis radius. The otherroot corresponds to the apoapsis radius, Ra.Please note that in practice spacecraft launchesare usually terminated at either perigee or apogee,i.e. = 90. This condition results in the minimumuse of propellant.Example Problem 8

PROBLEM 8A satellite is launched into Earth orbit whereits launch vehicle burns out at an altitude of250 km. At burnout the satellite's velocity is7,900 m/s with the zenith angle equal to 89 de-

grees. Calculate the satellite's altitude atperigee and apogee.SOLUTION, Given: r1 = (6,378.14 + 250) × 1,000

= 6,628,140 m v1 = 7,900 m/s

= 89o Equation (26),(Rp/r1)1,2 = (-C±SQRT[C2-4×(1-C)×-sin2 ])/

(2× (1 - C))where C = 2×GM/(r1 × v12)

C = 2×3.986005×1014/(6,628,140×7,9002) C = 1.927179(Rp / r1)1,2 = (-1.927179±SQRT[1.9271792-4×

-0.927179×-sin2(89)])/ (2 × -0.927179)(Rp / r1)1,2 = 0.996019 and 1.082521Perigee Radius, Rp = Rp1 = r1 × (Rp / r1)1 Rp = 6,628,140 × 0.996019 Rp = 6,601,750 mAltitude @ perigee = 6,601,750/1,000-6,378.14

= 223.6 kmApogee Radius, Ra = Rp2 = r1 × (Rp / r1)2 Ra = 6,628,140 × 1.082521 Ra = 7,175,100 mAltitude @ apogee = 7,175,100/1,000-6,378.14

= 797.0 km

Equation (26) gives the values of Rp and Ra fromwhich the eccentricity of the orbit can becalculated, however, it may be simpler to calculatethe eccentricity e directly from the equation

Example Problem 9

PROBLEM 9Calculate the eccentricity of the orbit for thesatellite in PROBLEM 8.SOLUTION, Given: r1 = 6,628,140 m v1 = 7,900 m/s

= 89o Equation (27),e = SQRT[(r1×v12/GM-1)2×sin2 +cos2 ]e = SQRT[(6,628,140×7,9002/

3.986005×1014-1)2×sin2(89)+cos2(89)]e = 0.0416170

To pin down a satellite's orbit in space, we need toknow the angle , the true anomaly, from theperiapsis point to the launch point. This angle isgiven by


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Example Problem 10

PROBLEM 10Calculate the angle from perigee point tolaunch point for the satellite in PROBLEM 8.SOLUTION, Given: r1 = 6,628,140 m v1 = 7,900 m/s

= 89o Equation (28),tan = (r1×v12/GM)×sin ×cos /

[(r1×v12/GM)×sin2 -1]tan = (6,628,140×7,9002/

3.986005×1014)×sin(89)×cos(89)/[(6,628,140×7,9002/3.986005×1014)×sin2(89)-1]

tan = 0.48329 = arctan(0.48329) = 25.794o

In most calculations, the complement of the zenithangle is used, denoted by . This angle is calledthe flight-path angle, and is positive when thevelocity vector is directed away from the primaryas shown in Figure 8. When flight-path angle isused, equations (26) through (28) are rewritten asfollows:

The semi-major axis is, of course, equal to(Rp+Ra)/2, though it may be easier to calculate itdirectly as follows:

Example Problem 11

PROBLEM 11Calculate the semi-major axis of the orbit forthe satellite in PROBLEM 8.SOLUTION, Given: r1 = 6,628,140 m v1 = 7,900 m/s

Equation (32),a = 1 / ( 2 / r1 - v12 / GM )a = 1/(2/6,628,140-7,9002/3.986005×1014))a = 6,888,430 m

If e is solved for directly using equation (27) or(30), and a is solved for using equation (32), Rpand Ra can be solved for simply using equations(21) and (22).Orbit Tilt, Rotation and OrientationAbove we determined the size and shape of theorbit, but to determine the orientation of the orbit inspace, we must know the latitude and longitudeand the heading of the space vehicle at burnout.Figure 9 on next page illustrates the location of aspace vehicle at engine burnout, or orbit insertion.

is the azimuth heading measured in degreesclockwise from north, is the geocentric latitude(or declination) of the burnout point, is theangular distance between the ascending node andthe burnout point measured in the equatorial plane,and is the angular distance between theascending node and the burnout point measured inthe orbital plane. 1 and 2 are the geographicallongitudes of the ascending node and the burnoutpoint at the instant of engine burnout. Figure 10pictures the orbital elements, where i is theinclination, is the longitude at the ascendingnode, is the argument of periapsis, and is thetrue anomaly.If , , and 2 are given, the other values can becalculated from the following relationships:

In equation (36), the value of is found usingequation (28) or (31). If is positive, periapsis iswest of the burnout point (as shown in Figure 10);if is negative, periapsis is east of the burnoutpoint.The longitude of the ascending node, , ismeasured in celestial longitude, while 1 isgeographical longitude. The celestial longitude ofthe ascending node is equal to the local apparentsidereal time, in degrees, at longitude 1 at thetime of engine burnout. Sidereal time is defined asthe hour angle of the vernal equinox at a specificlocality and time; it has the same value as the rightascension of any celestial body that is crossing the


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local meridian at that same instant. At the momentwhen the vernal equinox crosses the localmeridian, the local apparent sidereal time is 00:00(could be used any sidereal time calculation).Example Problem 12

PROBLEM 12For the satellite in PROBLEM 8, burnout occurs2000-10-20, 15:00 UT. The geocentriccoordinates at burnout are 32o N latitude, 60oW longitude, and the azimuth heading is 86o.Calculate the orbit's inclination, argument ofperigee, and longitude of ascending node.SOLUTION, Given: = 86o

= 32o

2 = -60o From PROBLEM 10,

= 25.794o Equation (33), cos(i) = cos( ) × sin( ) cos(i) = cos(32) × sin(86) i = 32.223o Equations (34) and (36),

tan( ) = tan( ) / cos( ) tan( ) = tan(32) / cos(86)

= 83.630o

= - = 83.630 - 25.794 = 57.836o

Equations (35) and (37), tan( ) = sin( ) × tan( ) tan( ) = sin(32) × tan(86)

= 82.483o

1 = 2 -1 = -60 - 82.4831 = -142.483o

= Sidereal time at -142.483longitude, 2000-10-20, 15:00 UT

= 7h 27' 34" = 111.892o

Position in an Elliptical OrbitJohannes Kepler was able to solve the problem ofrelating position in an orbit to the elapsed time, t-to,or conversely, how long it takes to go from onepoint in an orbit to another. To solve this, Keplerintroduced the quantity M, called the meananomaly, which is the fraction of an orbit periodthat has elapsed since perigee. The meananomaly equals the true anomaly for a circularorbit. By definition,

where Mo is the mean anomaly at time to and n isthe mean motion, or the average angular velocity,

determined from the semi-major axis of the orbit asfollows:

This solution will give the average position andvelocity, but satellite orbits are elliptical with aradius constantly varying in orbit. Because thesatellite's velocity depends on this varying radius, itchanges as well. To resolve this problem we candefine an intermediate variable E, called theeccentric anomaly, for elliptical orbits, which isgiven by

where is the true anomaly. Mean anomaly is afunction of eccentric anomaly by the formula

For small eccentricities a good approximation oftrue anomaly can be obtained by the followingformula (the error is of the order e3):

The preceding five equations can be used to (1)find the time it takes to go from one position in anorbit to another, or (2) find the position in an orbitafter a specific period of time. When solving theseequations it is important to work in radians ratherthan degrees, where 2 radians equals 360degrees.Example Problem 13

PROBLEM 13A satellite is in an orbit with a semi-majoraxis of 7,500 km and an eccentricity of 0.1.Calculate the time it takes to move from a


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position 30 degrees past perigee to 90 degreespast perigee.SOLUTION, Given: a = 7,500 × 1,000 = 7,500,000 m e = 0.1 tO = 0

O = 30 deg × /180 = 0.52360 radians= 90 deg × /180 = 1.57080 radians

Equation (40),cos E = (e + cos ) / (1 + e cos )Eo = arccos[(0.1+cos(0.52360))/

(1+0.1× cos(0.52360))]Eo = 0.47557 radians

E = arccos[(0.1+cos(1.57080))/(1+0.1×cos(1.57080))]

E = 1.47063 radiansEquation (41),

M = E - e × sin EMo = 0.47557 - 0.1 × sin(0.47557)Mo = 0.42978 radians

M = 1.47063 - 0.1 × sin(1.47063) M = 1.37113 radians Equation (39), n = SQRT[ GM / a3 ] n = SQRT[ 3.986005×1014 / 7,500,0003 ] n = 0.00097202 rad/s Equation (38), M - Mo = n × (t - tO) t = tO + (M - Mo) / n t = 0 + (1.37113 - 0.42978) / 0.00097202 t = 968.4 s

Example Problem 14

PROBLEM 14The satellite in PROBLEM 13 has a true anomalyof 90 degrees. What will be the satellite'sposition, i.e. it's true anomaly, 20 minuteslater?SOLUTION, Given: a = 7,500,000 m e = 0.1 tO = 0 t = 20 × 60 = 1,200 s

O = 90 × /180 = 1.57080 rad From PROBLEM 13, Mo = 1.37113 rad n = 0.00097202 rad/s Equation (38), M - Mo = n × (t - tO) M = Mo + n × (t - tO) M = 1.37113 + 0.00097202 × (1,200 - 0) M = 2.53755METHOD #1, Low Accuracy:Equation (42), ~ M + 2 × e × sin M + 1.25 × e2 × sin 2M ~ 2.53755 + 2 × 0.1 × sin(2.53755) +

1.25 × 0.12 × sin(2 × 2.53755)~ 2.63946 = 151.2 degrees

METHOD #2, High Accuracy:Equation (41),

M = E - e × sin E2.53755 = E - 0.1 × sin E

By iteration, E = 2.58996 radiansEquation (40),

cos E = (e + cos ) / (1 + e cos )Rearranging variables gives,cos = (cos E - e) / (1 - e cos E) = arccos[(cos(2.58996) - 0.1) /

(1 - 0.1 × cos(2.58996)] = 2.64034 = 151.3 degrees

At any time in its orbit, the magnitude of aspacecraft's position vector, i.e. its distance fromthe primary body, and its flight-path angle can becalculated from the following equations:

And the spacecraft's velocity is given by,

Example Problem 15

PROBLEM 15For the satellite in problems 4.13 and 4.14,calculate the length of its position vector,its flight-path angle, and its velocity whenthe satellite's true anomaly is 225 degrees.SOLUTION, Given: a = 7,500,000 m e = 0.1

= 225 degreesEquations (43) and (44),r = a×(1-e2)/(1+e×cos )r = 7,500,000×(1-0.12)/(1+0.1×cos(225))r = 7,989,977 m = arctan[e×sin /(1+ecos )] = arctan[0.1×sin(225)/(1+0.1×cos(225))] = -4.351 degrees

Equation (45),v = SQRT[GM×(2/r-1/a)]v = SQRT[3.986005×1014×(2/7,989,977-1/

7,500,000)]v = 6,828 m/s

To be continued…


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AAssttrroonnoommiiccaall CCoommppuuttiinngg -- GGlloobbuullaarr CClluusstteerr aanndd CCyybbeerr SSkkyy bbyy SSPPAACCEEAACCAADDEEMMYY..NNEETT

Globular ClusterA globular cluster is a very compact sphericalgroup of stars. It may typically contain 100,000 toten million stars, and is usually found in the halo ofthe galaxy rather than in the disc. The stars in aglobular cluster are population II stars which arered and thought to be older stars deficient inelements heavier than helium. Globular clustersare typically several hundred light years indiameter. The image above is a computersimulation of a globular cluster. A random numbergenerator is used to determine both the angularand radial position of each star in the cluster. Theangle is specified by a uniform distribution, but theradial position is given by a Gaussian distribution.

Approximately one hundred globular clusters havebeen found in the halo of the Milky Way. The mostfamous in the southern sky are Omega Centauriand 47 Tucanae. These are shown below forcomparison with the simulated cluster.The simulation was done with a very simpleQBASIC program whose source code is givenbelow so that you may create your own globularclusters.Cyber SkyComputer programs can be used to produce starimages. A random number generator is used todetermine both the position of a star in the "sky"and also its brightness. The apparent brightness ofthe star is varied by a combination of both theactual brightness of the point and its size.The sky images shown above and below weremade with a very simple QBASIC program whosesource code is given below so that you may createyour own 'cyber sky images'. Study the programand note how the number of stars varies accordingto their brightness.More computer generated star images are shownbelow. You might enjoy devising constellations forthe star groupings.

Note: For more stuff about space and rockets please visit:

www.spaceacademy.net

Top: Omega Centauri. Bottom: 47 Tucanae. Credit: ESO

The two simple programs written in BASIC simulates globular clusters and sky pictorially. The user specifies the numberof stars that the cluster is to contain. The resulting simulation is then plotted out.


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Listing 1 of 1

'Generate Globular Cluster [GCLUSTER.BAS]DIM level(3) 'magnitude levelsSCREEN 12 '640x480 pixelsPI = 3.14159 'to put angle in radiansFOR star = 1 TO 100000 '100,000 stars in cluster CLR = 8 'faintest star brightness IF star MOD 5 = 0 THEN CLR = 7 'intermediate start brightness IF star MOD 25 = 0 THEN CLR = 15 'brightest stars brightness theta = 2 * PI * RND 'select a radom angle 0 to 2pi 'now compute a radius with gaussian distribution about cluster centre

radius = (RND + RND + RND + RND + RND + RND - 3!) * 100 xp = 320 + radius * COS(theta) 'compute x coordinate of star yp = 240 + radius * SIN(theta) 'compute y coordinate of star PSET (xp, yp), CLR 'and plotNEXT starDO WHILE INKEY$ <> CHR$(27) 'wait until ESC key is pressedLOOPEND 'then terminate

'Generate starry sky [STARS.BAS]DIM level(3) 'magnitude levelsRANDOMIZE TIMER 'so that each sky is differentSCREEN 12 '640x480 pixelsm1 = 3 'average number of mag 1 stars (default 3)r = 8 'star number ratio per magnitude (default 8)totalstars = m1 * (1 + r + r * r + r * r * r) '# of stars in the skylevel(1) = m1 / totalstars 'compute levels to makelevel(2) = m1 * (1 + r) / totalstars '4 different magnitudeslevel(3) = m1 * (1 + r + r * r) / totalstarsDO 'this is the loop that generates a new sky CLS 'clear screen/sky FOR i = 1 TO totalstars 'generate stars one by one xp = RND * 640 'x position on the screen yp = RND * 480 'y position on the screen magtst = RND 'generate a number to determine magnitude mag = 4 'start by assuming faintest star IF magtst < level(3) THEN mag = 3 'then brighten if IF magtst < level(2) THEN mag = 2 'generated random number is IF magtst < level(1) THEN mag = 1 'within specified level SELECT CASE mag 'now plot star according to magnitude CASE 4 PSET (xp, yp), 8 'faintest star (try changing colour to 7?)

CASE 3 PSET (xp, yp), 15 'brightest star with a single point CASE 2 CIRCLE (xp, yp), 1, 15 'increase app brightness by increasing size PAINT (xp, yp), 15 CASE 1 CIRCLE (xp, yp), 1.5, 15 'brightest stars have largest area PAINT (xp, yp), 15 END SELECT NEXT i 'go back and plot all stars until finished DO a$ = INKEY$ 'wait for a keyboard input LOOP WHILE a$ <> CHR$(27) AND a$ <> "q" 'ESC generates new skyLOOP WHILE a$ <> "q" 'q quits programEND 'program end


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Modelled Globular Cluster. Credit: SPACEACADEMY.NET


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Cyber Sky. Credit: SPACEACADEMY.NET


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Top: The Mirror Tree Selection. Middle: The Foucault Test settings dialog.Bottom: The Ronchi Test settings dialog.

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SSooffttwwaarree RReevviieeww

II’m much pleasured to apply the new update ofMODAS NG ATM release. Of course the numbersof rewritten features maybe look not too reach, butthe work was enormously.What is new in this update?I was able to adapt four analyses to the new vectorgraphic - Foucaultgrams, Ronchigrams, Miulles-Lacroix Data Reduction and the real mirror profileby Roger Sinnott and Dmitri Macsutov. Twoanalyses - Ronchi-Mosby Null Test and TeribizhTest currently could not be adopted, maybe in thefeature. Under development is too the TexerauMirror Profile.I have optimized the settings of all mirror’s testssome properties was removed or added and bugshave bin fixed. For example all dialogs allow theuser to enter his own Title of the test and theassign of the design title (if a dsg file was opened)work now properly.Similar to other analyses like “RMS Spot Size vs.Field Angle” I have added the property “Scale GridType” (see below) the both Mirror’s Profile.All these analyses will be in the feature improvedand made easier to use. Unlimited number ofseries (mirror test trials) will be added, withadditional reporting features.What is still open? Adaptation to the vector graphicof the Geometrical analyses - Encircled Energyand MTF analyses and the Tabular and graphicalSeidel aberrations. I hope all this comes with thenext final update.After the final update, I wish to start with theoptimization, tolerancing, physical optics modulesand the 3D optical layout. Really I have alltheoretical stuff needed for the development andimprovement of these features! The 3D opticallayout will be based on the Open GL.Important bug fixes related all analyses wasapplied. After a window was maximized, thegraphic was not redraw correct!I hope you enjoy this release!

After many years of development MODAS NG ATM edition is near competition. This will be the last but one update.Only a few features are not rewritten in the new vector graphic. As I quit in the editor notes, MODAS NG willavailable in the next few years only as freeware (no commercial version will be available by some private reason).Still this MODAS NG ATM freeware will allow the users to enjoy many powerful features. Until Christmas will beavailable the final freeware release and I keep you informed.

MMOODDAASS NNGG UUppddaattee -- MMiirrrroorr TTeessttiinngg


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ggMMOODDAASS NNGG UUppddaattee -- MMiirrrroorr TTeessttiinngg

The Knife-Edge data reduction setting dialog. It allow the user to create up to 5 different series (in the feature unlimited number of series). The settingsdialog is used by both mirror’s profile analyse – by Roger Sinnott and Dmitri Maksutov.


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Millies-Lacroix Graph Approach in different graphic representation and styles.


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Left: Mirror Real Profil by Roger Sinnott in different graphic stiles. Right: Mirror Real profile by Dmitri Maksutov in different graphic styles.


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Through Focus Foucaultgrams in different colors.


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Left: Foucaultgrams in ROC. Right: Ronchigrams outside ROC.


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Through Focus Ronchigrams in different colors.


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Ronchigrams in ROC.


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Left: Ronchigrams inside ROC. Right: Ronchigrams outside ROC.


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Neil Armstrong (1930-2012)

Neil Armstrong, First Man on the Moon, Dies at 82.


His death was reported at 2:45 p.m. ET.Armstrong commanded the Apollo 11 spacecraftthat landed on the moon on July 20, 1969, and heradioed back to Earth the historic news: ”That’sone small step for a man, one giant leap formankind.”In a statement issued by the White House, U.S.President Barack Obama said “Today, Neil’s spiritof discovery lives on in all the men and womenwho have devoted their lives to exploring theunknown – including those who are ensuring thatwe reach higher and go further in space. Thatlegacy will endure - sparked by a man who taughtus the enormous power of one small step.”Neil Armstrong, along with fellow astronauts BuzzAldrin, Michael Collins and John Glenn, werehonored with the Congressional Gold Medal onNovember 16, 2011.

(Source: Universe Today/Jason Major)

Harry Harrison (1925-2012)Harry Harrison, the American science fiction writerbest known for the Stainless Steel Rat comicspace opera series and the dystopian Make Room!Make Room! has died at the age of 87.He also parodied the genre in his Bill the GalacticHero books, seeing his work as anti-war and anti-militaristic. Brian Aldiss, who worked with Harrisonon criticism and editing science fiction anthologies,called him "a constant peer and great familyfriend".Harrison's first novel, Deathworld, was published in1960, with the Stainless Steel Rat appearing forthe first time a year later. "Slippery Jim" diGriz, thebooks' anti-hero, whose latest appearance was in2010, was, one admirer pointed out onWednesday, a "rogue smuggler" created yearsbefore Han Solo in the Star Wars films.The central idea of Make Room! Make Room!, his1966 novel in which a critical food shortage inoverpopulated New York means a food substituteis needed, was used in the 1973 film SoylentGreen, starring Charlton Heston.

American science fiction author Harry Harrison, who also created theStainless Steel Rat comic space opera series, has died aged 87.

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The first man on the moon is no more. Legendary astronaut NeilArmstrong, the first man to set foot on the moon, has died at age 82.

Neil Armstrong (1930-2012)On August 25, 2012 we mourn the loss of a truehero and icon of a generation, if not an entirecentury: Neil Alden Armstrong, former NASAastronaut and first person to set foot on the Moon,has passed away due to complications fromcardiovascular surgery. Armstrong had recentlyturned 82 years old on August 5.His family has issued the following statement:We are heartbroken to share the news that NeilArmstrong has passed away followingcomplications resulting from cardiovascularprocedures.Neil was our loving husband, father, grandfather,brother and friend.Neil Armstrong was also a reluctant American herowho always believed he was just doing his job. Heserved his Nation proudly, as a navy fighter pilot,test pilot, and astronaut. He also found successback home in his native Ohio in business andacademia, and became a community leader inCincinnati.He remained an advocate of aviation andexploration throughout his life and never lost hisboyhood wonder of these pursuits.As much as Neil cherished his privacy, he alwaysappreciated the expressions of good will frompeople around the world and from all walks of life.While we mourn the loss of a very good man, wealso celebrate his remarkable life and hope that itserves as an example to young people around theworld to work hard to make their dreams cometrue, to be willing to explore and push the limits,and to selflessly serve a cause greater thanthemselves.For those who may ask what they can do to honorNeil, we have a simple request. Honor his exampleof service, accomplishment and modesty, and thenext time you walk outside on a clear night andsee the moon smiling down at you, think of NeilArmstrong and give him a wink.


Harry Harrison passed away in the early hours of Wednesday 15th August, 2012. Credit: Harry Harrison News Blog

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This imprint shows the right rear foot of a nodosaur - a low-slung, spinyleaf-eater - apparently moving in haste as the heel did not fully settle inthe cretaceous mud, according to dinosaur tracker Ray Stanford. It wasfound recently on NASA's Goddard Space Flight Center campus and isbeing preserved for study. Credit: Ray Stanford

determine whether further excavation is called for,and possibly to extract and preserve the existingfootprints. “Space scientists may walk along here, andthey’re walking exactly where this big, bunglingheavy armored dinosaur walked, maybe 110 to112 million years ago.” - Ray Stanford


With Proposed Cuts, Can the US Continue tobe a Leader in Astronomy? Q & A with NOAO

Director David SilvaReport from this August, 2012 issued by theNational Science Foundation’s Division ofAstronomical Sciences suggested de-fundingseveral ground-based observatories along withother money-saving strategies to help offsetbudget shortfalls in US astronomy which havebeen projected to be as much as 50%. The reportrecommended the closure of iconic facilities suchas the Very Long Baseline Array (VLBA) and theGreen Bank Radio Telescope, as well as shuttingdown four different telescopes at the Kitt PeakObservatory by 2017.Universe Today (UT) talked with the Director of theNational Optical Astronomy Observatory (NOAO),Dr. David Silva for his reactions to the report.Universe Today: What is your initial reaction to theSTP portfolio review:David Silva: “It’s disappointing, but not completelyunexpected. I think the biggest challenge for theoverall US community is they’re going to loseaccess to a lot of world-class, cutting-edgefacilities. This is roughly somewhere between eighthundred to a thousand nights of open access timewhich is going to be defunded over the next threeyears or so. That’s a huge culture change for USastronomy.UT: Do you see this affecting the researchers atsmaller facilities and universities the most?

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Harrison, an advocate of the internationallanguage Esperanto, which appears in several ofhis books, was born in Stamford, Connecticut, in1925and also lived for periods in Mexico, England,Ireland, Denmark and Italy. After service in theSecond World War and art study, he ran a studioselling illustrations to comics and science fictionmagazines; He married Joan (née Merkler) in 1954in New York. She died from cancer in 2002. Theyhad two children, Todd and Moira.

(Source: Guardian)

Multiple Dinosaur Tracks Confirmed atNASA Center

At NASA’s Goddard Space Flight Center inGreenbelt, MD, where some of the world’s mostadvanced research in space technology is beingperformed on a daily basis, paleontologists havediscovered ancient evidence of dinosaurs on theCenter’s wooded campus - at least two, possibly amother and child, crossed that way between 112and 110 million years ago and left their muddyfootprints as proof.The tracks of two nodosaurs - short, stocky andheavily-armored herbivorous dinosaurs - havebeen confirmed by dinosaur tracker Ray Stanfordand USGS emeritus paleontologist Dr. RobertWeems. The second track is a smaller version ofthe first.The first, larger footprint was announced byStanford on August 17, 2012. When Dr. Weemswas called in to verify, the smaller print wasdiscovered within the first, evidence that they weremade around the same time and leadingresearchers to suggest it may have been a mother-and-child pair.“It looks to be a manus (front foot) print of a muchsmaller dinosaur than the first one, but it looks tobe the same type,” Weems said of the secondtrack. “If the one that came through was a female,it may have had one or more young ones followingalong. If you’ve seen a dog or cat walking with itsyoung, they kind of sniff around and may not go inthe same direction, but they end up in the sameplace.”It’s thought that the nodosaurs were movingquickly since the tracks don’t show strong imprintsof the animals’ heels. Still, the ruddy Cretaceous-era mud preserved their brief passage well - evenas millions of years went by.“This was a large, armored dinosaur,” Stanfordsaid. “Think of it as a four-footed tank. It was quiteheavy, there’s a quite a ridge or push-up here.Subsequently the sand was bound together byiron-oxide or hematite, so it gave us a nicepreservation, almost like concrete.”The next steps will be to have the site analyzed to


Top: Fossilized nodosaur footprints discovered at NASA’s Goddard Space Flight Center in Maryland. Bottom: Dinosaur tracker Ray Stanford describes thecretaceous-era nodosaur track he found on the Goddard Space Flight Center campus with Dr. Robert Weems, emeritus paleontologist for the USGS whoverified his discovery. Credit: NASA/GSFC/Rebecca Roth

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federal level and there is going to be a squeezenow. I think that one of the choices we’re goingface as there is this squeeze and people begin toleave the field, how do we make sure that thethose who are still in the field - especially ouryounger colleagues - that they are given thementoring and nurturing and support they need tohave vital careers.But there’s a growing mismatch between thenumbers of people who want funding and thefunding that is available, there’s no two ways aboutit.UT: Any final thoughts or things that you think arepeople I’m important for people to know about?Silva: One of the opportunities that it creates onKitt Peak is the ability to continue to move forwardon our BigBOSS collaboration, which is a proposalto put a 5,000 target, multi-object spectrograph onthe 4-meter Mayall telescope at Kitt Peak NationalObservatory, which allows you to do a large darkenergy characterization experiment. Theinstrument is also exceptionally powerful for doinga variety of other investigations like galacticarchaeology to map out kinematics in the galaxy,the chemical composition and the motions ofgalaxies and stars, and other very large dataprojects like that.This report was actually quite supportive of thatproject moving forward. So even though reportsrecommend the NSF divest funding in the MayallTelescope as an open-access telescope, itsuggests there are ways forward to convert it froman open access platform to a survey facility. Andthat’s, I think, a silver lining in this. It doesn’t solvethat cultural issue, but it was does mean we cancontinue to do high impact science with thatinstrument.But I do see this as a big cultural change. A keyquestion perhaps is, does the US have strongnational observatory or not? And this report isleaning in the direction of not.

(Source: Universe Today/Nancy Atkinson)

Found: Two ‘Exact Matches’ to theMilky Way Galaxy

Here’s something astronomers haven’t seenbefore: galaxies that look just like our own MilkyWay. It’s not that our spiral-armed galaxy is rarebut instead the whole neighborhood in which wereside seems to be unusual. Until now, a galaxypaired with close companions like the MagellanicClouds has not been found elsewhere. But usingdata from a new radio astronomy survey,astronomers found two Milky Way look-alikes andseveral others that were similar.“We’ve never found another galaxy system like theMilky Way before, which is not surprising consider-

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The Kitt Peak Observatory. Credit: Universe Today

Silva: Definitely. Clearly, the situation is now that ifyou’re at an institution that has its own facility,everything should be OK. But if you’re at aninstitution that does not have access to its ownfacility, you’re in a bad situation. So that naturallysegregates the bigger universities versus thesmaller universities.I should say there is a caveat, in that we are in anera now in professional astronomy where surveysare now becoming a much stronger component ofwhat we do. Surveys are the big wide-field surveysboth from space and from the ground which areproducing massive datasets that are open toeveryone. So, what’s really happening is thisculture change from people having to compete forone or two nights a year on a telescope topotentially working on the big datasets. So, howthat transition occurs remains to be seen. But theloss of all these open access nights will definitelybe a shock to the system.UT: Do you see the new report as being overlypessimistic or do you think it’s spot on of what’sactually going to be taking place in astronomy nextfew years, such as in one scenario whichdescribed that only 50% of projected funding willbe available?Silva: I have no opinion on that. That was aboundary condition that the report used, and if Icould predict that I would be in a different industry!UT: Do you see any potential silver lining here, thatthis kind of tight funding could streamline things, orcould help in the “persistent mismatch between theproduction rate of Ph.D.s and the number oftenure-track faculty or long-term astronomypositions” that the report talked about?Silva: No. I think the higher-level issue is thatastronomy in the last 20 years has been a fieldwhere the number of people who are professionalastronomers has grown in this country because ofa fortuitous funding cycle from all three of themajor funding agents, NASA, NSF and theDepartment of Energy. But we are now in adownward cycle in funding for astronomy at the


haven’t been able to tell just how rare they are,until now, using the new survey which looks athundreds of thousands of galaxies.“We found about 3% of galaxies similar to theMilky Way have companion galaxies like theMagellanic Clouds, which is very rare indeed,”Robotham said. “In total we found 14 galaxysystems that are similar to ours, with two of thosebeing an almost exact match.”The Milky Way is locked in a complex cosmicdance with its close companions the Large andSmall Magellanic Clouds, which are clearly visiblein the southern hemisphere night sky. Manygalaxies have smaller galaxies in orbit aroundthem, but few have two that are as large as theMagellanic Clouds.Robotham and his team will continue searching formore Milky Way twin systems.


Light trick to see around cornersScientists have found a novel way to get imagesthrough "scattering" materials such as frostedglass or skin, and even to "see around corners".Much research in recent years has focused oncorrecting for scattering, mostly for medicalapplications.But the new trick, reported in Nature Photonics, isquick, simple and uses natural light rather thanlasers.It uses what is called a spatial light modulator to"undo" the scattering that makes objects opaque ornon-reflecting.A camera that can "see around corners" garneredmuch attention in 2010, using a series of timedlaser pulses to illuminate a scene and working outwhat is around a corner from the timing of thereflections.The prototype device was just one of a great manyresearch efforts trying to crack the problem ofscattering.But for some applications, the "time-of-flight"approach that the laser-based camera uses is notsufficient."If you want to look to see an embryo developinginside an egg but the eggshell scatters everything,or you want to look through the skin, scattering isthe main enemy there, and time-of-flight is not agood solution," explained senior author of thestudy Prof Yaron Silberberg.For those kinds of problems, Prof Silberberg andhis colleagues at the Weizmann Institute ofScience in Israel have pushed the limits of whatspatial light modulators (SLMs) can do.SLMs modify what is known as the phase of anincoming light beam. Like a series of waves on the

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This image shows one of the two ‘exact matches’ to the Milky Way systemfound in a new survey. The larger galaxy, denoted GAMA202627, which issimilar to the Milky Way clearly has two large companions off to thebottom left of the image. Credit: Dr Aaron Robotham, ICRAR/StAndrews using GAMA data

ing how hard they are to spot!” said Dr. AaronRobotham with the International Centre for RadioAstronomy Research (ICRAR). “It’s only recentlybecome possible to do the type of analysis that letsus find similar groups.”“Everything had to come together at once,”Robotham added. “We needed telescopes goodenough to detect not just galaxies but their faintcompanions, we needed to look at large sectionsof the sky, and most of all we needed to make sureno galaxies were missed in the survey.”Robotham presented his new findings at theInternational Astronomical Union General Assem-bly in Beijing this August, 2012.Using what astronomer consider the most detailedmap of the local Universe yet - the Galaxy andMass Assembly survey (GAMA) - Robotham andhis colleagues found that although companions likethe Magellanic Clouds are rare, when they arefound they’re usually near a galaxy very like theMilky Way, meaning we’re in just the right place atthe right time to have such a great view in our nightsky.“The galaxy we live in is perfectly typical, but thenearby Magellenic Clouds are a rare, and possiblyshort-lived, occurrence. We should enjoy themwhilst we can, they’ll only be around for a fewbillion more years,” said Robotham.Astronomers have used computer simulations ofhow galaxies form and they don’t produce manyexamples similar to the Milky Way and itssurroundings, so they have predicted them to bequite a rare occurrence. Astronomers they really


well when the light from an object bounces off apiece of paper; the SLM could "learn" how to undothe paper's scattering effect, making it a nearlyperfect reflector.As Prof Silberberg puts it: "You can take a piece ofwall and effectively turn it into a mirror, and this isthe part that makes everybody raise an eyebrow."However, he said that the primary use for thetechnique will be in biological and medical studies -especially tackling the highly scattering white brainmatter in neurological imaging - rather than thebusiness of seeing through thin materials oraround corners."I don't want to say that it solves the problems ofsecret organisations and Peeping Toms and so on,that's not going to be so simple. But the principle isthere."We have not started to tackle these things... but Isee how much interest this raises and think maybewe should." (Source: BBC/Jason Palmer)

Worlds Without Suns: Nomad Planets CouldNumber In The Quadrillions

The concept of nomad planets has been featuredbefore here on Universe Today, and for goodreason. Not only is the idea of mysterious loneplanets drifting sunless through interstellar spacean intriguing one, but also the sheer potentialquantity of such worlds is simply staggering. Ifsome very well-respected scientists’ calculationsare correct there are more nomad planets in ourMilky Way galaxy than there are stars - a lot more.With estimates up to 100,000 nomad planets forevery star in the galaxy, there could be literallyquadrillions of wandering worlds out there, rangingin size from Pluto-sized to even larger than Jupiter.That’s a lot of nomads. But where did they allcome from?Recently, The Kavli Foundation had a discussionwith several scientists involved in nomad planetresearch. Roger D. Blandford, Director of the KavliInstitute for Particle Astrophysics and Cosmology(KIPAC) at Stanford University, Dimitar D.Sasselov, Professor of Astronomy at HarvardUniversity and Louis E. Strigari, ResearchAssociate at KIPAC and the SLAC NationalAccelerator Laboratory talked about their findingsand what sort of worlds these nomad planets mightbe, as well as how they may have formed.One potential source for nomad planets is forcefulejection from solar systems.“Most stars form in clusters, and around manystars there are protoplanetary disks of gas anddust in which planets form and then potentially getejected in various ways,” said Strigari. “If theseearly-forming solar systems have a large number

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The letter A with no scattering (top), behind scattering plastic (centre)and re-imaged with the new technique. Credit: Silverburg

ocean that run over rocks or surfers, the waves inlight can be slowed down or redirected when theyhit scattering materials.SLMs are made up of an array of pixels that cancorrect for this by selectively slowing down someparts of the beam and allowing others to passuntouched - when an electric field is applied to apixel, it changes the speed at which light passesthrough it.Prof Silberberg and his team first set up their SLMby shining light from a normal lamp through ahighly scattering plastic film and allowing acomputer to finely tune the SLM until they couldsee a clear image of the lamp through the film.Keeping the SLM set this way, they were then ableto obtain clear images of other objects through thefilm - the SLM effectively turns the film back into aclear sheet."What we have shown is that you don't need lasers- everybody else was doing this with lasers, andwe showed you can do it with incoherent light froma lamp or the Sun - natural light," Prof Silberbergtold BBC News.But the team then realised that the same approachcan work in reflection - that is, not passing througha scattering material but bouncing off of it, such asthe case of light bouncing off a wall at a corner.They then showed the procedure works just as


There could be quadrillions of nomad planets in our galaxy alone -- and they could even be ejected into intergalactic space. Credit: ESO/S.Brunier

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written about it too, as recently as three weeksago, and it’s still a much-debated topic.)“In the 20th century, many eminent scientists haveentertained the speculation that life propagatedeither in a directed, random or malicious waythroughout the galaxy,” said Blandford. “One thingthat I think modern astronomy might add to that isclear evidence that many galaxies collide andspray material out into intergalactic space. So lifecan propagate between galaxies too, in principle.“And so it’s a very old speculation, but it’s aperfectly reasonable idea and one that is becomingmore accessible to scientific investigation.”Nomad planets may not even be limited to theconfines of the Milky Way. Given enough of apush, they could be sent out of the galaxy entirely.“Just a stellar or black hole encounter within thegalaxy can, in principle, give a planet the escapevelocity it needs to be ejected from the galaxy. Ifyou look at galaxies at large, collisions betweenthem leads a lot of material being cast out intointergalactic space,” Blandford said.


Higgs-like Particle Discovered at CERNPhysicists working at the Large Hadron Collider(LHC) have announced the discovery of what theycalled a “Higgs-like boson” - a particle thatresembles the long sought-after Higgs.“We have reached a milestone in ourunderstanding of nature,” CERN director generalRolf Heuer told scientists and media at aconference near Geneva on July 4, 2012. “Thediscovery of a particle consistent with the Higgsboson opens the way to more detailed studies,requiring larger statistics, which will pin down thenew particle’s properties, and is likely to shed lighton other mysteries of our universe.”Two experiments, ATLAS and CMS, presentedtheir preliminary results, and observed a newparticle in the mass region around 125-126 GeV,the expected mass range for the Higgs Boson. Theresults are based on data collected in 2011 and2012, with the 2012 data still under analysis. Theofficial results will be published later this monthand CERN said a more complete picture of today’sobservations will emerge later this year after theLHC provides the experiments with more data.“We observe in our data clear signs of a newparticle, at the level of 5 sigma, in the mass regionaround 126 GeV. The outstanding performance ofthe LHC and ATLAS and the huge efforts of manypeople have brought us to this exciting stage,” saidATLAS experiment spokesperson Fabiola Gianotti,“but a little more time is needed to prepare theseresults for publication.”The discovery of the Higgs is big, in that it is the

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Artist's concept of a free-floating Jupiter-like planet.Credit: NASA/JPL-Caltech

of planets down to the mass of Pluto, you canimagine that exchanges could be frequent.”And the possibility of planetary formation outside ofstellar disks is not entirely ruled out by theresearchers - although they do impose a lower limitto the size of such worlds.“Theoretical calculations say that probably thelowest-mass nomad planet that can form by thatprocess is something around the mass of Jupiter,”said Strigari. “So we don’t expect that planetssmaller than that are going to form independent ofa developing solar system.”“This is the big mystery that surrounds this newpaper. How do these smaller nomad planetsform?” Sasselov added.Of course, without a sun of their own to supplyheat and energy one might assume such worldswould be cold and inhospitable to life. But, as theresearchers point out, that may not always be thecase. A nomad planet’s internal heat could supplythe necessary energy to fuel the emergence oflife… or at least keep it going.“If you imagine the Earth as it is today becoming anomad planet… life on Earth is not going tocease,” said Sasselov. “That we know. It’s noteven speculation at this point. …scientists alreadyhave identified a large number of microbes andeven two types of nematodes that survive entirelyon the heat that comes from inside the Earth.”Researcher Roger Blandford also suggested that“small nomad planets could retain very dense,high-pressure ‘blankets’ around them. These couldconceivably include molecular hydrogenatmospheres or possibly surface ice that wouldtrap a lot of heat. They might be able to keep waterliquid, which would be conducive to creating orsustaining life.”And so with all these potentially life-sustainingplanets knocking about the galaxy is it possiblethat they could have helped transport organismsfrom one solar system to another? It’s a conceptcalled panspermia, and it’s been around since atleast the 5th century BCE when the Greekphilosopher Anaxagoras first wrote about it. (We’ve


understanding the 96% of the universe thatremains obscure. - CERN press release“We have reached a milestone in ourunderstanding of nature,” said CERN DirectorGeneral Rolf Heuer. “The discovery of a particleconsistent with the Higgs boson opens the way tomore detailed studies, requiring larger statistics,which will pin down the new particle’s properties,and is likely to shed light on other mysteries of ouruniverse.”Positive identification of the new particle’scharacteristics will take more time and moreexperiments. But the scientists feel that whateverform the Higgs particle takes, our knowledge of thefundamental structure of matter is about to take amajor step forward.


Visions of the Cosmos: The Enduring SpaceArt of David A. Hardy

For over 50 years, award-winning space andastronomy artist David A. Hardy has taken us toplaces we could only dream of visiting. His careerstarted before the first planetary probes blasted offfrom Earth to travel to destinations in our solarsystem and before space telescopes vieweddistant places in our Universe. It is striking to viewhis early work and to see how accurately hedepicted distant vistas and landscapes, and surely,his paintings of orbiting space stations and baseson the Moon and Mars have inspired generationsof hopeful space travellers.

Hardy published his first work in 1952 when hewas just 15. He has since illustrated and producedcovers for dozens of science and science fictionbooks and magazines. He has written andillustrated his own books and has worked withastronomy and space legends like Patrick Moore,Arthur C. Clarke, Carl Sagan, Wernher von Braun,and Isaac Asimov. His work has been exhibitedaround the world, including at the National Air &Space Museum in Washington, D.C. which housestwo of his paintings.

Universe Today is proud to announce that Hardyhas helped us update the banner at the top of ourwebsite (originally designed by Christopher Sisk)to make it more astronomically accurate.

Hardy has also recently debuted his own newwebsite where visitors can peruse and learn moreabout his work, and buy prints and other items.We had the chance to talk with Hardy about hisenduring space art and career:UT: When you first started your space art, thereweren’t images from Voyager, Cassini, Hubble,etc. to give you ideas for planetary surfaces andcolored space views. What was your inspiration?

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Event recorded with the CMS detector in 2012 at a proton-proton centreof mass energy of 8 TeV. The event shows characteristics expected fromthe decay of the SM Higgs boson to a pair of photons (dashed yellow linesand green towers). The event could also be due to known standard modelbackground processes. Credit: CERN

last undiscovered piece of the Standard Model thatdescribes the fundamental make-up of theuniverse.Scientists believe that the Higgs boson, named forScottish physicist Peter Higgs, who first theorizedits existence in 1964, is responsible for particlemass, the amount of matter in a particle. Accordingto the theory, a particle acquires mass through itsinteraction with the Higgs field, which is believed topervade all of space and has been compared tomolasses that sticks to any particle rolling throughit.And so, in theory, the Higgs would be responsiblefor how particles come together to form matter,and without it, the universe would have remained aformless miss-mash of particles shooting around atthe speed of light.“It’s hard not to get excited by these results,” saidCERN Research Director Sergio Bertolucci. “Westated last year that in 2012 we would either find anew Higgs-like particle or exclude the existence ofthe Standard Model Higgs. With all the necessarycaution, it looks to me that we are at a branchingpoint: the observation of this new particle indicatesthe path for the future towards a more detailedunderstanding of what we’re seeing in the data.”A CERN press release says that the next step willbe to determine the precise nature of the particleand its significance for our understanding of theuniverse.

Are its properties as expected for the long-sought Higgs boson, the final missing ingredient inthe Standard Model of particle physics? Or is itsomething more exotic? The Standard Modeldescribes the fundamental particles from whichwe, and every visible thing in the universe, aremade, and the forces acting between them. All thematter that we can see, however, appears to be nomore than about 4% of the total. A more exoticversion of the Higgs particle could be a bridge to


Top: 'Moon Landing:'' This is one of Hardy's very earliest paintings, done in 1952 when he was just 15. It was also the first to be published. Credit: DavidA. Hardy. Used by permission. Bottom: 'Skiing on Europe' by David A. Hardy, 1981. Used by permission.

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Top: 'Ferry Rocket and Space Station' by David A. Hardy. Used by permission. Hardy’s description: ‘A wheel-shaped space station as designed by Wernhervon Braun, and a dumbbell-shaped deep-space vehicle designed by Arthur C. Clarke to travel out to Mars and beyond. The only photographs of the Earthfrom space at this time were a few black-and-white ones from captured German V-2s.’ Bottom: 'Mars From Deimos' 1956. Credit: David A. Hardy. Used bypermission. Hardy's description: 'The dumbell-shaped spaceship (designed by Arthur C. Clarke) shown in the previous 'space station' image has arrived,touching down lightly in the low gravity of Mars's little outer moon, Deimos. The polar cap is clearly visible, and at that time it was still considered possiblethat the dark areas on Mars were caused by vegetation, fed by the melting caps. On the right of the planet is Phobos, the inner moon.'

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Earth. Through these I have been to the volcanoesof Hawaii and Iceland, to Death Valley CA, theGrand Canyon and Meteor Crater, AZ, toNicaragua. . . all of these provide not justinspiration but analogues of other worlds like Mars,Io or Triton, so that we can make our work morebelievable and authentic - as well as morebeautiful, hopefully.UT: How has technology changed how you do yourwork?Hardy: I have always kept up with new technology,making use of xeroxes, photography (I used to doall my own darkroom work and processing), andmost recently computers. I got an Atari ST with512k (yes, K!) of RAM in 1986, and my first Mac in1991. I use Photoshop daily, but I use hardly any3D techniques, apart from Terragen to producebasic landscapes and Poser for figures. I do feelthat 3D digital techniques can make art moreimpersonal; it can be difficult or impossible to knowwho created it! And I still enjoy painting in acrylics,especially large works on which I can use ‘impasto’- laying on paint thickly with a palette knife andintroducing textures that cannot be produceddigitally!UT: Your new website is a joy to peruse - howdoes technology/the internet help you to shareyour work?Hardy: Thank you. It is hard now to remember howwe used to work when we were limited to sendingwork by mail, or faxing sketches and so on. Theability to send first a low-res jpeg for approval, andthen a high-res one to appear in a book or on amagazine cover, is one of the main advantages,and indeed great joys, of this new technology.UT: I imagine an artist as a person working alone.However, you are part of a group of artists and areinvolved heavily in the Association of ScienceFiction and Fantasy Artists. How helpful is it tohave associations with fellow artists?Hardy: It is true that until 1988, when I met otherIAAA artists (both US, Canadian and, then, Soviet,including cosmonaut Alexei Leonov) in Iceland Ihad considered myself something of a lone wolf.So it was almost like ‘coming out of the closet’ tomeet other artists who were on the samewavelength, and could exchange notes, hints andtips.UT: Do you have a favorite image that you’vecreated?Hardy: Usually the last! Which in this case is acommission for a metre-wide painting on canvascalled ‘Ice Moon’. I put this on Facebook, where ithas received around 100 comments and ‘likes’ - allfavourable, I’m glad to say. It can be seen there onmy page, or on my own website, www.astroart.org

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David Hardy: I got to look through a telescopewhen I was about 16. You only have to see thelong shadows creeping across a lunar crater toknow that this is a world. But I also found the book‘The Conquest of Space‘ in my local library, andChesley Bonestell’s photographic paintings of theMoon and planets just blew me away! I knew that Iwanted to produce pictures that would showpeople what it’s really like out there - not just asrather blurry discs of light through a telescope.UT: And now that we have such spacecraftsending back amazing images, how has thatchanged your art, or how have the space imagesinspired you?Hardy: I was lucky to start when I did, because in1957 we had Sputnik, and then the exploration ofspace really started. We started getting photos ofthe Earth from space, and of the Moon fromprobes and orbiters, then of Mars, and eventuallyfrom the outer planets. Each of these made itpossible to produce better and more realistic andaccurate paintings of these worlds.UT: We are amazed at your early work - you wereso young and doing such amazing space art! Howdoes it feel to have inspired several generations ofpeople? - Surely your art has driven many to say,“I want to go there!”Hardy: I certainly hope so - that was the idea! In1954 I met the astronomer Patrick Moore, whoasked me to illustrate a new book in 1954, and wehave continued to work together until the presentday. Back then we wanted to so a sort of Britishversion of The Conquest of Space, which wecalled ‘The Challenge of the Stars.’ In the 1950swe couldn’t find a publisher - they all said it was‘too speculative!’ But a book with that title waspublished in 1972; ironically (and unbelievably),just when humans visited the Moon for the lasttime. We had hoped that the first Moon-landingswould lead to a base, and that we would go on toMars, but for all sorts of reasons (mainly political)this never happened. In 2004 Patrick and Iproduced a book called ‘Futures: 50 Years inSpace,’ celebrating our 50 years together. It wassubtitled: ‘The Challenge of the Stars: What wethought then - What we know now.’I quite often find that younger space artists tell methey were influenced by The Challenge of theStars, just as I was influenced by The Conquest ofSpace, and this is a great honour.UT: What places on Earth have most inspired yourart?Hardy: I’m a past President (and now EuropeanVP) of the International Association ofAstronomical Artists (IAAA; www.iaaa.org), and wehold workshops in the most ‘alien’ parts of Planet


'Antares 2' by David A. Hardy, shows a landscape looking up at the red supergiant star, which we see in Scorpio and is one of the biggest and brighteststars known. It has a small bluish companion, Antares B.

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The Leonids over Stonhenge by David A. Hardy. Used by permission

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'Ice Moon' by David Hardy. Used by permission.

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According to a press release from UCLA,astronomers used the sharp eyes of the HubbleSpace Telescope to spy on 300 very distantgalaxies in the early Universe. The scientistsoriginally thought their galaxy, one of the mostmassive in their survey going by the unglamorousname of BX442, was an illusion, perhaps twogalaxies superimposed on each other.“The fact that this galaxy exists is astounding,” saidDavid Law, lead author of the study and DunlapInstitute postdoctoral fellow at the University ofToronto’s Dunlap Institute for Astronomy &Astrophysics. “Current wisdom holds that such‘grand-design’ spiral galaxies simply didn’t exist atsuch an early time in the history of the universe.” A‘grand design’ galaxy has prominent, well-formedspiral arms.To understand their image further, astronomersused a unique, state-of-the-art instrument calledthe OSIRIS spectrograph at the W.M. KeckObservatory atop Hawaii’s dormant Mauna Keavolcano. The instrument, built by UCLA professorJames Larkin, allowed them to study light fromabout 3,600 locations in and around BX442. Thisspectra gave them the clues they needed to showthey were indeed looking at a single, rotating spiralgalaxy.While spiral galaxies are abundant throughout thecurrent cosmos, that wasn’t always the case.Spiral galaxies in the early Universe were rarebecause of frequent interactions. “BX442 looks likea nearby galaxy, but in the early universe, galaxieswere colliding together much more frequently,”says Shapely. “Gas was raining in from theintergalactic medium and feeding stars that werebeing formed at a much more rapid rate than theyare today; black holes grew at a much more rapidrate as well. The universe today is boringcompared to this early time.”

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(UT note: this is a painting in acrylics on stretchedcanvas, with the description,”A blue ice moon of agas giant, with a derelict spaceship which shouldn’tlook like a spaceship at first glance.”)UT: Anything else you feel is important for peopleto know about your work?Hardy: I do feel that it’s quite important for peopleto understand the difference between astronomicalor space art, and SF (‘sci-fi’) or fantasy art. Thelatter can use a lot more imagination, but oftencontains very little science - and often gets it quitewrong. I also produce a lot of SF work, which canbe seen on my site, and have done around 70covers for ‘The Magazine of Fantasy & ScienceFiction’ since 1971, and many for ‘Analog’. I’m VicePresident of the Association of Science Fiction &Fantasy Artists (ASFA; www.asfa-art.org) too. But Ialways make sure that my science is right! I wouldalso like to see space art more widely accepted inart galleries, and in the Art world in general; we dotend to feel marginalised.UT: Thank you for providing Universe Today with amore “accurate” banner - we really appreciate yourcontribution to our site!Hardy: My pleasure.


Oldest Spiral Galaxy in the UniverseDiscovered

Ancient starlight traveling for 10.7 billion years hasbrought a surprise - evidence of a spiral galaxylong before other spiral galaxies are known to haveformed.“As you go back in time to the early universe,galaxies look really strange, clumpy and irregular,not symmetric,” said Alice Shapley, a UCLAassociate professor of physics and astronomy, andco-author of a study reported in today’s journalNature. “The vast majority of old galaxies look liketrain wrecks. Our first thought was, why is this oneso different, and so beautiful?”Galaxies today come in a variety of unique shapesand sizes. Some, like our Milky Way Galaxy, arerotating disks of stars and gas called spiralgalaxies. Other galaxies, called elliptical galaxies,resemble giant orbs of older reddish stars movingin random directions. Then there are a host ofsmaller irregular shaped galaxies bound togetherby gravity but lacking in any visible structure. Agreat, diverse population of these types of irregulargalaxies dominated the early Universe, saysShapely.Light from this incredibly distant spiral galaxy,traveling at nearly six trillion miles per year, took10.7 billion years to reach Earth; just 3 billion yearsafter the Universe was created in an event calledthe Big Bang.


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An artist’s rendering of galaxy BX442 and its companion dwarf galaxy (upper left).Credit: Dunlap Institute for Astronomy & Astrophysics/Joe Bergeron


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These stunning photos of the Aurora Australis and the Milky Way was captured from what may be the coldest and most isolated research facility on Earth: theFrench-Italian Concordia Base station, located at 3,200 meters (nearly 10,500 feet) altitude on the Antarctic plateau, 1,670 km (1,037 miles) from thegeographic south pole. Taken by Dr. Alexander Kumar, a doctor, researcher and photographer who’s been living at the Base since January, the image showsthe full beauty of the sky above the southern continent - a sky that doesn’t see the Sun from May to August.


no sunlight and no transportation in or out fromMay to August, Concordia Base is incrediblyisolated - so much so that it’s used for research formissions to Mars, where future explorers will facemany of the same challenges and extremeconditions that are found at the Base.But even though they may be isolated, Dr. Kumarand his colleagues are in an excellent location towitness amazing views of the sky, the likes ofwhich are hard to find anywhere else on Earth.Many thanks to them for braving the bitter cold andotherworldly environment to share images like thiswith us!“The dark may cause fear, but if you take the timeto adapt and look within it, you never know whatyou may find - at the bottom of the ocean, in thenight sky, or under your bed in the middle of thenight,” writes Kumar on the Concordia blog. “If youdon’t overcome your fear of the ‘unknown’ and‘monsters’, you will never see marvellous secretshidden in the dark.“I hope this photo inspires you too for the days,weeks and months ahead. In terms of the spaceexploration we are only beginning. We have tocontinue pushing out into the great beyond.”


Nearby Magma Exoplanet is SmallerThan Earth

Astronomers have detected what could be one ofthe smallest exoplanets found so far, just two-thirds the size of Earth. And, cosmically speaking,it’s in our neighborhood, at just 33 light-yearsaway. But this planet, called UCF-1.01, is not aworld most Earthlings would enjoy visiting: it likelyis covered in magma.“We have found strong evidence for a very small,

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Shapely and Law think the gravitational tug-of-warbetween a dwarf galaxy companion and BX442may be responsible for its futuristic look. Thecompanion appears as just a small blob in theirimage. Computer simulations conducted byCharlotte Christensen, a postdoctoral student atthe University of Arizona and co-author of thepaper, lends evidence to this idea. Eventually,BX442 and the smaller galaxy likely will merge.Shapley said BX442 represents a link betweenearly galaxies that are much more turbulent andthe rotating spiral galaxies that we see around us.“Indeed, this galaxy may highlight the importanceof merger interactions at any cosmic epoch increating grand design spiral structure,” she said.Studying BX442 is likely to help astronomersunderstand how spiral galaxies like the Milky Wayform, she added.

(Source: Universe Today/John WIlliamns)

Aurora and Milky Way over Antarctica“We managed to snap a few photos before Heavenrealised its mistake and closed its doors.”

– Dr. Alexander KumarThe stunning photos of the Aurora Australis andMilky Way (see previos page), set against abackdrop of the Milky Way, was captured from oneof the most remote research locations on theplanet: the French-Italian Concordia Base, locatedlocated at 3,200 meters (nearly 10,500 feet)altitude on the Antarctic plateau, 1,670 km (1,037miles) from the geographic south pole.The photos was taken on July 18 by residentdoctor and scientist Dr. Alexander Kumar and hiscolleague Erick Bondoux.Of course, taking photos outside is no easy task.Temperatures outside the Base in winter can dropdown to -70ºC (-100ºF)!Sparked by a coronal mass ejection emitted fromactive region 11520 on July 12, Earth’s auroraeleapt into high gear both in the northern andsouthern hemispheres three days later during theresulting geomagnetic storm - giving somewonderful views to skywatchers in locations likeAlaska, Scotland, New Zealand… and even theSouth Pole.“A raw display of one of nature’s most incrediblesights dazzled our crew,” Dr. Kumar wrote on hisblog, Chronicles from Concordia. “The wind dieddown and life became still. To me, it was if Heavenhad opened its windows and a teardrop had fallenfrom high above our station, breaking the darklonely polar night.“We managed to snap a few photos before Heavenrealised its mistake and closed its doors.”With winter temperatures as low as -70ºC (-100ºF),


were periodic, suggesting a second planet mightbe orbiting the star and blocking out a smallfraction of the star’s light.From the data, the astronomers were able to gleansome basic properties of this exoplanet: itsdiameter is approximately 8,400 kilometers (5,200miles ), or two-thirds that of Earth. UCF-1.01 wouldrevolve quite tightly around its star, GJ 436, atabout seven times the distance of Earth from themoon, with its “year” lasting only 1.4 Earth days.Given this proximity to its star, far closer than theplanet Mercury is to our sun, the exoplanet’ssurface temperature would be almost 600 degreesCelsius (about 1,000 degrees Fahrenheit).The planet likely does not have an atmosphere,being so close to the star UCR-1.01’s might be ahot lava world.“The planet could even be covered in magma,”said Joseph Harrington, also of the University ofCentral Florida and principal investigator of theresearch.In addition to UCF-1.01, the researchers noticedhints of a third planet, dubbed UCF-1.02, orbitingGJ 436. Spitzer has observed evidence of the twonew planets several times each. However, eventhe most sensitive instruments are unable tomeasure exoplanet masses as small as UCF-1.01and UCF-1.02, which are perhaps only one-thirdthe mass of Earth. Knowing the mass is requiredfor confirming a discovery, so the paper authorsare cautiously calling both bodies exoplanetcandidates for now.Remove this adWhile this is Spitzer’s first potential extra solarplanet, the exoplanet-hunting Kepler spacecrafthas identified 1,800 stars as candidates for havingplanetary systems, and just three are verified tocontain sub-Earth-sized exoplanets. Of these, onlyone exoplanet is thought to be smaller than theSpitzer candidates, with a radius similar to Mars, or57 percent that of Earth.“I hope future observations will confirm theseexciting results, which show Spitzer may be able todiscover exoplanets as small as Mars,” saidMichael Werner, Spitzer project scientist atNASA’s Jet Propulsion Laboratory in Pasadena,Calif. “Even after almost nine years in space,Spitzer’s observations continue to take us in newand important scientific directions.”


Possible Subterranean Life Means MoreExoplanets Could Harbor Life

When we think of life on other planets, we tend toimagine things (microbes, plant life and yes,humanoids) that exist on the surface. But Earth’sbiosphere doesn’t stop at the planet’s surface, and

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Caption: This artist’s concept shows what astronomers believe is an alien world justtwo-thirds the size of Earth. Credit: NASA/JPL-Caltech

very hot and very near planet with the help of theSpitzer Space Telescope,” said Kevin Stevensonfrom the University of Central Florida in Orlando,lead author of a new paper in The AstrophysicalJournal. “Identifying nearby small planets such asUCF-1.01 may one day lead to theircharacterization using future instruments.”This is the first time an exoplanet has been foundusing Spitzer, so astronomers are now rethinkingthis space telescope’s role in helping discoverpotentially habitable, terrestrial-sized worlds.However, the hot, new-planet candidate was foundunexpectedly in Spitzer observations. Stevensonand his colleagues were studying the Neptune-sized exoplanet GJ 436b, already known to existaround the red-dwarf star GJ 436. In the Spitzerdata, the astronomers noticed slight dips in theamount of infrared light streaming from the star,separate from the dips caused by GJ 436b. Areview of Spitzer archival data showed the dips


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Top:Artistic representation of the current five known potential habitable worlds. Will this list broaden under a new habitability model?; Bottom: Location inthe night sky of the stars with potential habitable exoplanets (red circles). There are two in Gliese 581. Click the image for larger version.

Credit: The Planetary Habitability Laboratory (PHL)/UPR Arecibo and Jim Cornmell


If this notion catches on - which it should - it willhave exoplanet hunters recalculating the amountof potentially habitable worlds.


“Impossible” Binary Star Systems FoundAstronomers think about half of the stars in ourMilky Way galaxy are, unlike our Sun, part of abinary system where two stars orbit each other.However, they’ve also thought there was a limit onhow close the two stars could be without merginginto one single, bigger star. But now a team ofastronomers have discovered four pairs of stars invery tight orbits that were thought to be impossiblyclose. These newly discovered pairs orbit eachother in less than 4 hours.Over the last three decades, observations haveshown a large population of stellar binaries, andnone of them had an orbital period shorter than 5hours. Most likely, the stars in these systems wereformed close together and have been in orbitaround each other from birth onwards.A team of astronomers using the United KingdomInfrared Telescope (UKIRT) in Hawaii made thefirst investigation of red dwarf binary systems. Reddwarfs can be up to ten times smaller and athousand times less luminous than the Sun.Although they form the most common type of starin the Milky Way, red dwarfs do not show up innormal surveys because of their dimness in visiblelight.But astronomers using UKIRT have beenmonitoring the brightness of hundreds ofthousands of stars, including thousands of reddwarfs, in near-infrared light, using its state-of-the-art Wide-Field Camera (WFC).“To our complete surprise, we found several reddwarf binaries with orbital periods significantlyshorter than the 5 hour cut-off found for Sun-likestars, something previously thought to beimpossible,” said Bas Nefs from LeidenObservatory in the Netherlands, lead author of thepaper which was published in journal MonthlyNotices of the Royal Astronomical Society. “Itmeans that we have to rethink how these close-inbinaries form and evolve.”Since stars shrink in size early in their lifetime, thefact that these very tight binaries exist means thattheir orbits must also have shrunk as well sincetheir birth, otherwise the stars would have been incontact early on and have merged. However, it isnot at all clear how these orbits could have shrunkby so much.One possible scenario is that cool stars in binarysystems are much more active and violent thanpreviously thought.The astronomers said it is possible that the

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neither would life on another world, says a newstudy that expands the so-called ‘Goldilocks Zone’to include the possibility of subterranean habitablezones. This new model of habitability could vastlyincrease where we could expect to find life, as wellas potentially increasing the number of habitableexoplanets.We know that a large fraction of the Earth’sbiomass is dwelling down below, and recentlymicrobiologists discovered bacterial life, 1.4kilometers below the sea floor in the North Atlantic,deeper in the Earth’s crust than ever before. Thisand other drilling projects have brought upevidence of hearty microbes thriving in deep rocksediments. Some derive energy from chemicalreactions in rocks and others feed on organicseepage from life on the surface. But most liferequires at least some form of water.“Life ‘as we know it’ requires liquid water,” saidSean McMahon, a PhD student from the Universityof Aberdeen’s (Scotland) School of Geosciences.“Traditionally, planets have been considered‘habitable’ if they are in the ‘Goldilocks zone’. Theyneed to be not too close to their sun but also nottoo far away for liquid water to persist, rather thanboiling or freezing, on the surface. However, wenow know that many micro-organisms perhaps halfof all living things on Earth reside deep in the rockycrust of the planet, not on the surface.”Remove this adWhile suns warm planet surfaces, there’ also heatfrom the planets’ interiors. Crust temperatureincreases with depth so planets that are too coldfor liquid water on the surface may be sufficientlywarm underground to support life.“We have developed a new model to show how‘Goldilocks zones’ can be calculated forunderground water and hence life,” McMahon said.“Our model shows that habitable planets could bemuch more widespread than previously thought.”In the past, the Goldilocks zone has really beendetermined by a circumstellar habitable zone(CHZ), which is a range of distances from a star,and depending on the star’s characteristics, thezone varies. The consensus has been that planetsthat form from Earth-like materials within a star’sCHZ are able to maintain liquid water on theirsurfaces.But McMahon and his professor, John Parnell, alsofrom Aberdeen University who is leading the studynow are introducing a new term: subsurface-habitability zone (SSHZ). This denote the range ofdistances from a star within which planets arehabitable at any depth below their surfaces up to acertain maximum, for example, they mentioned a“SSHZ for 2 km depth”, within which planets cansupport liquid water 2 km or less underground.


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This artist’s impression shows the tightest of the new record breaking binary systems. Two active M4 type red dwarfs orbit each other every 2.5 hours, asthey continue to spiral inwards. Eventually they will coalesce into a single star. Credit: J. Pinfield


Artist's illustration of Pluto's surface. Credit: NASA

nitrogen. This gas would expand from the planet’s,dwarf planet’s - surface as it came closer to theSun during the course of its eccentric 248-yearorbit and then freeze back onto the surface as itmoved further away. The new findings from theUniversity of St Andrews team, made byobservations with the James Clerk Maxwelltelescope in Hawaii, identify an even thickeratmosphere containing carbon monoxide thatextends over 3000 km, reaching nearly halfway toPluto’s largest moon, Charon.It’s possible that this carbon monoxide atmospheremay have expanded outwards from Pluto,especially in the years since 1989 when it madethe closest approach to the Sun in its orbit. Surfaceheating (and the term “heating” is usedscientifically here…remember, at around -240ºC (-400ºF) Pluto would seem anything but balmy tous!) by the Sun’s radiation would have warmed thesurface and expelled these gases outwards. Thisalso coincides with observations made by theHubble Space Telescope over the course of fouryears, which revealed varying patterns of dark andlight areas on Pluto’s surface – possibly caused bythe thawing of frozen areas that shift and reveallighter surface material below. “Seeing such an example of extra-terrestrialclimate-change is fascinating. This cold simpleatmosphere that is strongly driven by the heat fromthe Sun could give us important clues to how someof the basic physics works, and act as acontrasting test-bed to help us better understandthe Earth’s atmosphere.”

- Dr. Jane Greaves, Team Leader

In fact, carbon monoxide may be the key to whyPluto even still has an atmosphere. Unlikemethane, which is a greenhouse gas, carbonmonoxide acts as a coolant; it may be keepingPluto’s fragile atmosphere from heating up toomuch and escaping into space entirely! Over thedecades and centuries that it takes for Pluto tocomplete a single year, the balance between these

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magnetic field lines radiating out from the cool starcompanions get twisted and deformed as theyspiral in towards each other, generating the extraactivity through stellar wind, explosive flaring andstar spots. Powerful magnetic activity could applythe brakes to these spinning stars, slowing themdown so that they move closer together.“The active nature of these stars and theirapparently powerful magnetic fields has profoundimplications for the environments around reddwarfs throughout our Galaxy, ” said team membersaid David Pinfield from the University ofHertfordshire.UKIRT has a 3.8 meter diameter mirror, and is thesecond largest dedicated infrared telescope in theworld. It sits at an altitude of 4,200 m on the top ofthe volcano Mauna Kea on the island of Hawaii.


More Surprises From PlutoAh, Pluto. Seems every time we think we’ve got itfigured out, it has a new surprise to throw at us.First spotted in 1930 by a young Clyde Tombaugh,for 76 years it enjoyed a comfortable position asthe solar system’s most distant planet. Then acontroversial decision in 2006 by the InternationalAstronomical Union, spurred by suggestions fromastronomer (and self-confessed “planet-killer”)Mike Brown*, relegated Pluto to a new class ofworlds called “dwarf planets”. Not quite planetsand not quite asteroids, dwarf planets cannotentirely clear their orbital path with their owngravitational force and thus miss out on fullplanetary status. Besides immediately making a lotof science textbooks obsolete and rendering thehandy mnemonic “My Very Eager Mother JustServed Us Nine Pies” irrelevant (or at leastconfusing), the decision angered many peoplearound the world, both in and out of the scientificcommunity. Pluto is a planet, they said, it alwayshas been and always will be! Save Pluto! theschoolkids wrote in crayon to planetariumdirectors. The world all of a sudden realized howmuch people liked having Pluto as the “last” planet,and didn’t want to see it demoted by decision,especially a highly contested one.Yet as it turns out, Pluto really may not be a planetafter all.It may be a comet. But…that’s getting ahead ofourselves. First things first.Recent discoveries by a UK team of astronomerspoints to the presence of carbon monoxide inPluto’s atmosphere. Yes, Pluto has anatmosphere; astronomers have known about itsince 1988. At first assumed to be about 100kmthick, it was later estimated to extend out about1500km and be composed of methane gas and


the many inherent dangers of living and working inspace - the Moon itself may be toxic to humans.An international team of researchers hasattempted to quantify the health dangers of theMoon - or at least its dust-filled regolith. In a papertitled “Toxicity of Lunar Dust” (D. Linnarsson et al.)the health hazards of the Moon’s fine, powderydust - which plagued Apollo astronauts both in andout of their suits - are investigated in detail (or asbest as they can be without actually being on theMoon with the ability to collect pristine samples.)Within their research the team, which includedphysiologists, pharmacologists, radiologists andtoxicologists from 5 countries, investigated some ofthe following potential health hazards of lunar dust:Inhalation. By far the most harmful effects of lunardust would come from inhalation of theparticulates. Even though lunar explorers would bewearing protective gear, suit-bound dust can easilymake its way back into living and working areas -as Apollo astronauts quickly discovered. Onceinside the lungs the super-fine, sharp-edged lunardust could cause a slew of health issues, affectingthe respiratory and cardiovascular system andcausing anything from airway inflammation toincreased risks of various cancers. Like pollutantsencountered on Earth, such as asbestos andvolcanic ash, lunar dust particles are small enoughto penetrate deep within lung tissues, and may bemade even more dangerous by their long-termexposure to proton and UV radiation. In addition,the research suggests a microgravity environmentmay only serve to ease the transportation of dustparticles throughout the lungs.Skin Damage. Lunar regolith has been found to bevery sharp-edged, mainly because it hasn’tundergone the same kind of erosive processesthat soil on Earth has. Lunar soil particles aresometimes even coated in a glassy shell, the resultof rock vaporization by meteorite impacts. Eventhe finer particles of dust - which constitute about20% of returned lunar soil samples - are rathersharp, and as such pose a risk of skin irritation ininstances of exposure. Of particular note by theresearch team is abrasive damage to the outerlayer of skin at sites of “anatomical prominence”,i.e., fingers, knuckles, elbows, knees, etc. “The dust was so abrasive that it actually worethrough three layers of Kevlar-like material on Jack[Schmitt's] boot.”

- Professor Larry Taylor, Director of thePlanetary Geosciences Institute, University ofTennessee (2008)Eye Damage. Needless to say, if particles canpose abrasive damage to human skin, similardanger to the eyes is also a concern. Whether

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Artist's impression of Pluto's huge atmosphere of carbon monoxide. Thesource of this gas is erratic evaporation from the mottled icy surface ofthe dwarf planet. The Sun appears at the top, as seen in the ultra-violetradiation that is thought to force some of the dramatic atmosphericchanges. Pluto's largest moon, Charon, is seen to the lower right.

Credit: P.A.S. Cruickshank

two gases must be extremely precise.Actually this is an elaboration of the researchresults coming from the same team at theUniversity of St Andrews. The additional elementhere is a tiny redshift detected in the carbonmonoxide signature, indicating that it is movingaway from us in an unusual way. It’s possible thatthis could be caused by the top layers of Pluto’satmosphere - where the carbon monoxide resides -being blown back by the solar wind into, literally, atail.That sounds an awful lot, to this particularastronomy reporter anyway, like a comet.Just saying.Anyway, regardless of what Pluto is or isn’t, will becalled or used to be called, there’s no denying thatit is a fascinating little world that deserves ourattention. (And it will be getting plenty of that comeJuly 2015 when the New Horizons spacecraftswings by for a visit!) I’m sure there’s no one herewho would argue that fact.New Horizons’ upcoming visit will surely answermany questions about Pluto - whatever it is - andmost likely raise even more.


The Moon Is ToxicAs our closest neighbor in space, a time-capsule ofplanetary evolution and the only world outside ofEarth that humans have stepped foot on, the Moonis an obvious and ever-present location for futureexploration by humans. The research that can bedone on the Moon - as well as from it - will beinvaluable to science. But the only times humanshave visited the Moon were during quick, dustyjaunts on its surface, lasting only 2-3 days eachbefore departing. Long-term human exposure tothe lunar environment has never been studied indepth, and it’s quite possible that - in addition to


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Apollo 16 astronaut Charlie Duke with a dust-coated LRV. Side image: a dusty Gene Cernan in the LM at the end of an Apollo 17 EVA. Credit: NASA/JSC


A Black Brant sounding rocket containing NASA’s HI-C mission will launchon July 11, 2012 to observe the sun’s corona. (NASA) Bottom image:TRACE image of the Sun at a resolution of 0.5 arcsec/pixel. HI-C will havea resolution 5 times finer. Credit: NASA

given pixel - that structures in the sun’satmosphere are about 100 miles across,” saidJonathan Cirtain, project scientist for HI-C atNASA’s Marshall Space Flight Center. “And wealso have theories about the shapes of structuresin the atmosphere, or corona, that expect that size.HI-C will be the first chance we have to see them.”One of the main goals of HI-C will be to placesignificant new constraints on theories of coronalheating and structuring, by observing the small-scale processes that exist everywhere in hotmagnetized coronal plasma and establishingwhether or not there are additional structuresbelow what can currently be seen.“This instrument could push the limits on theoriesof coronal heating, answering questions such aswhy the temperature of the sun’s corona is millionsof degrees higher than that of the surface,” saidMarshall’s Dr. Jonathan Cirtain, heliophysicist andprinciple investigator on the mission.


Space Junk: Ideas for Cleaning up Earth OrbitSpace may be big - vastly, hugely, mind-bogglinglybig - but the space around Earth is beginning toget cluttered with space junk. This poses a threat,not only to other satellites, space stations andmissions, but to us here on Earth as well. While wewrestle with environmental issues posed by humanactivity on our planet, ESA’s new ‘Clean Space’initiative aims to address the same issues for itsmissions, making them greener by using more

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lunar dust makes its way into the eye via airbornemovement (again, much more of a concern inmicrogravity) or through direct contact from fingersor another dust-coated object, the result is thesame: danger of abrasion. Having a scratchedcornea is no fun, but if you’re busy working on theMoon at the time it could turn into a realemergency.

While the research behind the paper used dataabout airborne pollutants known to exist on Earthand simulated lunar dust particles, actual lunardust is harder to test. The samples returned by theApollo missions have not been kept in a true lunar-like environment - being removed from exposure toradiation and not stored in a vacuum, for instance -and as such may not accurately exhibit theproperties of actual dust as it would beencountered on the Moon. The researchersconclude that only studies conducted on-site will fillthe gaps in our knowledge of lunar dust toxicity.Still, the research is a step in the right direction asit looks to ensure a safe environment for futureexplorers on the Moon, our familiar - yet still alien -satellite world. (Source: Universe Today/Jason Major)

NASA To Launch The Finest Mirrors Ever MadeThis Wednesday NASA will launch its HighResolution Coronal Imager (HI-C) mission fromWhite Sands Missile Range in New Mexico,sending a sounding rocket above the atmospherewith some of the best mirrors ever made to captureincredibly-detailed ultraviolet images of our Sun.

HI-C will use a state-of-the-art imaging system tofocus on a region near the center of the Sun about135,000 miles (271,000 km) across. During its briefflight - only ten minutes long - HI-C will returnsome of the most detailed images of the Sun’scorona ever acquired, with a resolution five timesthat of previous telescopes… including NASA’sSolar Dynamics Observatory.

While SDO collects images in ten wavelengths,however, HI-C will focus on just one: 193Angstroms, a wavelength of ultraviolet radiationthat best reveals the structures of the Sun’s coronapresent in temperatures of 1.5 million kelvin. Andalthough HI-C’s mirrors aren’t any larger thanSDO’s - about 9.5 inches in diameter - they are“some of the finest ever made.” In addition, aninterior “maze” between mirrors effectivelyincreases HI-C’s focal length.

Researchers expect HI-C’s super-smooth mirrorsto resolve coronal structures as small as 100 miles(160 km) across (0.1 arcsec/pixel).

“Other instruments in space can’t resolve thingsthat small, but they do suggest - after detailedcomputer analysis of the amount of light in any


operation. The rest are derelict and liable tofragment as leftover fuel or batteries explode.Traveling at around 7.5 km/s, a 2 cm screw has a‘lethal diameter’ sufficient to take out a satellite.Taking the recent loss of the Envisat satellite as anexample, this satellite now poses a considerablethreat as space junk. An analysis of space debrisat Envisat’s orbit suggests there is a 15% to 30%chance of collision with another piece of junkduring the 150 years it is thought Envisat couldremain in orbit. The satellite’s complexity and sizemeans even a small piece of debris could cause a“fragmentation event” producing its own populationof space garbage. Envisat is also too big to beallowed to drift back into the Earth’s atmosphere.The choices seem to be to raise the satellite to ahigher, unused orbit, or guide it back in over thePacific Ocean.As ESA Director General Jean-Jacques Dordainsays “We will not succeed alone; we will needeveryone’s help. The entire space sector has to bewith us.” (Source: Universe Today/Jenny Winder)

Rethinking the Source of Earth’s WaterEarth, with its blue hue visible from space, isknown for its abundant water - predominatelylocked in oceans - that may have come from anextraterrestrial source. New research indicates thatthe source of Earth’s water isn’t from ice-richcomets, but instead from water-bearing asteroids.Looking at the ratio of hydrogen to deuterium, aheavy isotope of hydrogen, in frozen water,scientists can get a pretty good idea of thedistance the water formed in the solar system.Comets and asteroids farther from the Sun have ahigher deuterium content than ice formed closer tothe Sun. Scientists, led by the Carnegie Institutionfor Science’s Conel Alexander, compared waterfrom comets and from carbonaceous chondrites.What they found challenges current models in howthe solar system formed.Primeval Earth was a hot and dry place. Any waterthat may have formed with Earth was boiled awayfrom the scorching crust. Ultraviolet light from thenewly formed Sun stripped hydrogen atoms fromthe water molecules leaving no rain to fall back onthe surface. Scientists believe that both cometsand carbonaceous asteroids formed beyond theorbit of Jupiter, perhaps at the very fringes of thesolar system, then moved inward bringing bothwater and organic material to Earth. If this weretrue, Alexander and his colleagues suggest that icefound in comets and the remnants of ice preservedin carbonaceous chondrites in the form of clayswould have similar isotopic composition.After studying 85 carbonaceous chondrites,supplied by Johnson Space Center and theMeteorite Working Group, they show in a paper

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Artist’s impression of debris in low earth orbit Credit: ESA

eco-friendly materials and finding ways to cut downlevels of space debris.Last month ESA and Eurospace organized theClean Space Eco-design and Green TechnologiesWorkshop 2012 held in the Netherlands. CleanSpace is a major objective of Agenda 2015, theAgency’s upcoming action plan. The aim wasoutlined by ESA Director General Jean-JacquesDordain: “If we are convinced that spaceinfrastructure will become more and moreessential, then we must transmit the spaceenvironment to future generations as we found it,that is, pristine.”The workshop looked at all aspects of spacemissions, their total environment impact, fromconcept development to end of life. The impact ofregulations regarding substances such ashydrazine, which is used widely as a propellant inspace programs and the development of GreenPropulsion with propellants that have a reducedtoxicity. Environmental friendliness andsustainability often mean increased efficiency,which ESA hopes will give the industry acompetitive advantage, so they are looking attechnologies which will consume less energy andproduce less waste, therefore cutting costs.Finally they looked at debris mitigation to minimizethe impact to the space environment as well as thedebris footprint on Earth using controlled anduncontrolled re-entry events and passive de-orbiting systems along with active de-orbiting andre-orbiting systems. They are even consideringtethers or sails to help drag abandoned satellitesout of low orbit within 25 years. New ‘design fordemise’ concepts hope to prevent chunks ofsatellites surviving re-entry and hitting the groundintact. Active removal of existing debris is alsoneeded, including robotic missions to repair or de-orbit satellites.6,000 satellites have been launched during theSpace Age; less than 1000 of these are still in


massive filament that stretched across 18megaparsecs (nearly 59 million light-years) ofspace. The alignment of the string enhanced thelensing effect.The team’s results were published in the July 4,2012 issue of Nature.“It looks like there’s a bridge that shows that thereis additional mass beyond what the clusterscontain,” Dietrich said in a press release. “Theclusters alone cannot explain this additional mass.”By examining X-rays emanating from plasma in thefilament, observed from the XMM-Newton satellite,the team calculated that no more than nine percentof the filament’s mass could be made up of the hotgas. Computer simulations further suggested thatjust 10 percent of the mass was due to visible starsand galaxies. Only dark matter, says Dietrich,could make up the remaining mass.“What’s exciting,” says Mark Bautz, anastrophysicist at the Massachusetts Institute ofTechnology, “is that in this unusual system we canmap both dark matter and visible matter togetherand try to figure out how they connect and evolvealong the filament.”Refining the technique could help physicistsunderstand the structure of the Universe and pin

Dark-matter filaments, such as the one bridging the galaxy clusters Abell222 and Abell 223, are predicted to contain more than half of all matter inthe Universe.

Credit: Jörg Dietrich, Univ. of Michigan/Univ. Observatory Munich

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Artist impression of an asteroid impact on early Earth. Credit: NASA

released today by Science Express that they likelydid not form in the same regions of the solarsystem as comets because they have much lowerdeuterium content. They formed closer to the Sun,perhaps in the asteroid belt between Mars andJupiter. And its that material that rained on earlyEarth to create the wet planet we know today.“Our results provide important new constraints forthe origin of volatiles in the inner solar system,including the Earth,” Alexander said. “And theyhave important implications for the current modelsof the formation and orbital evolution of the planetsand smaller objects in our solar system.”

(Source: Universe Today/John Williams)

Dark Matter Filaments Bind Galaxies TogetherA slim bridge of dark matter - just a hint of a largercosmic skeleton - has been found binding a pair ofdistant galaxies together.According to a press release from the journalNature, scientists have traced a thread-likestructure resembling a cosmic web for decades butthis is the first time observations confirming thatstructure has been seen. Current theory suggeststhat stars and galaxies trace a cosmic web acrossthe Universe which was originally laid out by darkmatter – a mysterious, invisible substance thoughtto account for more than 80 percent of the matterin the Universe. Dark matter can only be sensedthrough its gravitational tug and only glimpsedwhen it warps the light of distant galaxies.Astronomers led by Jörg Dietrich, a physicsresearch fellow in the University of MichiganCollege of Literature, Science and the Arts, tookadvantage of this effect by studying thegravitational lensing of galactic clusters Abell 222and 223. By studying the light of tens of thousandsof galaxies beyond the supercluster; located about2.2 billion light-years from Earth, the scientistswere able to plot the distortion caused by the Abellcluster. The scientists admit it is extremely difficultto observe gravitational lensing by dark matter inthe filaments because they contain little mass.Their workaround was to study a particularly


This deep image shows the region of the sky around the quasar HE0109-3518, near the center of the image. The energetic radiation of the quasarmakes dark galaxies glow, helping astronomers to understand the obscureearly stages of galaxy formation.

Credit: ESO, Digitized Sky Survey 2 and S. Cantalupo (UCSC)

The team detected almost 100 gaseous objectslying within a few million light-years of the quasar,and narrowed the possible dark galaxies down to12 objects. The team says these are the mostconvincing identifications of dark galaxies in theearly Universe to date.“Our observations with the VLT have providedevidence for the existence of compact and isolateddark clouds,” said Sebastiano Cantalupo from theUniversity of California, Santa Cruz, lead author ofthe paper. “With this study, we’ve made a crucialstep towards revealing and understanding theobscure early stages of galaxy formation and howgalaxies acquired their gas.”The astronomers were also able to determinesome of the properties of the dark galaxies, andestimate that the mass of the gas in them is about1 billion times that of the Sun, typical for gas-rich,low-mass galaxies in the early Universe. Theywere also able to estimate that the star formationefficiency is suppressed by a factor of more than100 relative to typical star-forming galaxies foundat similar stage in cosmic history.


The Return of the Rings!Now that Cassini has gone off on a new trajectorytaking it above and below the equatorial plane ofSaturn, we’re back to getting some fantastic viewsof the rings - the likes of which haven’t been seenin over two and a half years!The next image shows portions of the thin, ropy Fring and the outer A ring, which is split by the

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down the identity of dark matter (whether it’s a coldslow-moving mass or a warm, fast-moving one.Different types would clump differently along thefilament, say scientists.


Dark Galaxies Found from the Early UniverseHow do you find a dark galaxy? Shine some lighton the subject. Dark galaxies - ancient galaxiesthat contain little to no stars - have been theorizedto exist but have not been observed, until now. Aninternational team of astronomers think they havedetected these elusive objects by observing themglowing as they are illuminated by a quasar.Dark galaxies are small, gas-rich galaxies in theearly Universe that are very inefficient at formingstars. They are predicted by theories of galaxyformation and are thought to be the building blocksof today’s bright, star-filled galaxies. Astronomersthink that they may have fed large galaxies withmuch of the gas that later formed into the stars thatexist today.Being essentially devoid of stars, these darkgalaxies don’t emit much light, making them veryhard to detect. For years astronomers have beentrying to develop new techniques that couldconfirm the existence of these galaxies. Smallabsorption dips in the spectra of backgroundsources of light have hinted at their existence.However, this new study marks the first time thatsuch objects have been seen directly.“Our approach to the problem of detecting a darkgalaxy was simply to shine a bright light on it,” saidSimon Lilly, from the Institute for Astronomy atETH Zurich, Switzerland) co-author of a new paperpublished in the Monthly Notices of the RoyalAstronomical Society. “We searched for thefluorescent glow of the gas in dark galaxies whenthey are illuminated by the ultraviolet light from anearby and very bright quasar. The light from thequasar makes the dark galaxies light up in aprocess similar to how white clothes areilluminated by ultraviolet lamps in a night club.”Fluorescence is the emission of light by asubstance illuminated by a light source. Quasarsare very bright, distant galaxies, and theirbrightness makes them powerful beacons that canhelp to illuminate the surrounding area, probing theera when the first stars and galaxies were formingout of primordial gas.In order to detect the extremely faint fluorescentglow of these dark galaxies, the team used theVery Large Telescope (VLT), and took a series ofvery long exposures, mapping a region of the skyaround the bright quasar HE 0109-3518. Theylooked for the ultraviolet light that is emitted byhydrogen gas when it is subjected to intenseradiation.


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Credit: NASA/JPL/Space Science Institute


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Credit: NASA/JPL/Space Science Institute


Artist's illustration of a planet within a cluster.Credit: NASA/JPL-Caltech

planets orbiting within a dense cluster of starscalled the Beehive Cluster; a collection of 1,000stars collected around a common center of gravity- Nightfall worlds?!Well, not so fast. These worlds are “hot Jupiters;”massive, boiling hot planets that orbit their parentstar closer than Mercury in our own Solar System.The two new planets have been designatedPr0201b and Pr0211b after “Praesepe”, anothername for the Beehive Cluster. Although they aren’thabitable, the view from those planets in a densecluster of stars would be awe inspiring, withhundreds of stars within a radius of 12 light-years.Astronomers had long predicted that planetsshould be common in star clusters. Consider thatour own Solar System probably formed within astar forming complex like the Orion Nebula. Thenthe individual stars drifted away from each otherover time, taking their planets with them. Theevolution of the Beehive cluster was different,though, with the mutual gravity of the 1,000+ starsholding themselves together over hundreds ofmillions of years. “We are detecting more and more planets that canthrive in diverse and extreme environments likethese nearby clusters,” said Mario R. Perez, theNASA astrophysics program scientist in the Originsof Solar Systems Program. “Our galaxy containsmore than 1,000 of these open clusters, which

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202-mile (325-km) -wide Encke gap. The shepherdmoon Pan can be seen cruising along in the gapalong with several thin ringlets. Near the A ring’souter edge is a narrower space called the Keelergap - this is the home of the smaller shepherdmoon Daphnis, which isn’t visible here (but is oneof my personal favorites!)The scalloped pattern on the inner edge of theEncke gap downstream from Pan and a spiralpattern moving inwards from that edge are createdby the 12.5-mile-wide (20-km-wide) moon’sgravitational influence.Other features that have returned for an encoreperformance are the so-called propellers, spiralsprays of icy ring material created by tiny micro-moons within the rings. Individually too small todiscern (less than half a mile in diameter) thesepropeller moons kick up large clumps of reflectivering particles with their gravity as they travelthrough the rings, revealing their positions.The two images above show a propeller within theA ring. Nicknamed “Sikorsky” after Russian-American aviator Igor Sikorsky, the entire structureis about 30 miles (50 km) across and is one of themore well-studied propellers.Scientists are eager to understand the interactionsof propellers in Saturn’s rings as they may hold akey to the evolution of similar systems, such assolar systems forming from disks of matter.See a video of a propeller orbiting within the ringshere, and here’s an image of one that’s largeenough to cast a shadow!“One of the main contributing factors to theenormous success we on the Cassini mission haveenjoyed in the exploration of Saturn is thecapability to view the planet and the bodies aroundit from a variety of directions,” Cassini ImagingTeam Leader Carolyn Porco wrote earlier today.“Setting the spacecraft high into orbit aboveSaturn’s equator provides us direct views of theequatorial and middle latitudes on the planet andits moons, while guiding it to high inclination abovethe equator plane affords the opportunity to viewthe polar regions of these bodies and be treated tovertigo-inducing shots of the planet’s gloriousrings.” (Source: Universe Today/Nancy Atkinson)

Planets Found in a Cluster of Buzzing StarsThere’s a classic science fiction story calledNightfall, written by the late-great Isaac Asimov.It’s the tale of a world with six suns that fill the skywith such brightness that the inhabitants have noconcept of night. And then one day, a once-in-a-thousand-years alignment causes all the stars toset at once; and everyone goes crazy!In another case of science following sciencefiction, NASA-funded astronomers havediscovered


Early Galaxy Found from the Cosmic‘Dark Ages’

Take a close look at the pixelated red spot on thelower right portion of the image above, as it mightbe the oldest thing humanity has ever seen. This isa galaxy from the very early days of the Universe,and the light from the primordial galaxy traveledapproximately 13.2 billion light-years beforereaching the Spitzer and Hubble space telescopes.The telescopes - and the astronomers using them -had a little help from a gravitational lens effect tobe able to see such a faint and distant object,which was shining way back when our Universewas just 500 million years old.“This galaxy is the most distant object we haveever observed with high confidence,” said WeiZheng, a principal research scientist in thedepartment of physics and astronomy at JohnsHopkins University in Baltimore who is lead authorof a new paper appearing in Nature. “Future workinvolving this galaxy, as well as others like it thatwe hope to find, will allow us to study theuniverse’s earliest objects and how the dark agesended.”This ancient and distant galaxy comes from animportant time in the Universe’s history - one whichastronomers know little about - the early part of theepoch of reionization, when the Universe began tomove from the so-called cosmic dark ages. Duringthis period, the Universe went from a dark, starlessexpanse to a recognizable cosmos full of galaxies.The discovery of the faint, small galaxy opens awindow onto the deepest, most remote epochs ofcosmic history.“In essence, during the epoch of reionization, thelights came on in the universe,” said paper co-author Leonidas Moustakas, from JPL.Because both the Hubble and Spitzer telescopeswere used in this observation, this newfoundgalaxy, named MACS 1149-JD, was imaged in fivedifferent wavebands. As part of the ClusterLensing And Supernova Survey with HubbleProgram, the Hubble Space Telescope registeredthe newly described, far-flung galaxy in four visibleand infrared wavelength bands. Spitzer measuredit in a fifth, longer-wavelength infrared band,placing the discovery on firmer ground.Objects at these extreme distances are mostlybeyond the detection sensitivity of today’s largesttelescopes. To catch sight of these early, distantgalaxies, astronomers rely on gravitational lensing,where the gravity of foreground objects warps andmagnifies the light from background objects. Amassive galaxy cluster situated between ourgalaxy and MACS 1149-JD magnified thenewfound galaxy’s light, brightening the remoteobject some 15 times and bringing it into view.

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Beehive Cluster.Credit: Tom Bash and John Fox/Adam Block/NOAO/AURA/NSF

potentially can present the physical conditions forharboring many more of these giant planets.”Until now, only two planets had been uncoveredaround massive stars in star clusters, but nonearound sun-like stars within these clusters. So thepossibility of life was out of the question. Thesesuper-jupiters aren’t habitable either, but it’spossible that smaller planets will turn up in time aswell.The planets were discovered by using the 1.5-meter Tillinghast telescope at the SmithsonianAstrophysical Observatory’s Fred LawrenceWhipple Observatory near Amado, Arizona tomeasure the slight gravitational wobble the orbitingplanets induce upon their host stars.This discovery might help astronomers withanother mystery that has been puzzling them for afew years: how can hot Jupiters form? How can amassive planet form so close to their parent star?Instead of forming close, it’s possible that theconstant gravitational interactions among stars inyoung clusters push planets back and forth. Someare spun out into space as rogue planets, whileothers spiral inward and settle into these tightorbits.Could there be life on Earth-sized worlds withinthese clusters? Are there civilizations out therewho have never known the concept of night?Probably not.According to other researchers who released theirfindings just a week before the Tillinghast study,planets within star clusters like the Beehiveprobably aren’t habitable. In a paper titled, Canhabitable planets form in clustered environments?,a team of European astronomers considered theenvironmental effects of star clusters on theformation and evolution of planetary systems.According to their simulations, there are just toomany dynamic gravitational encounters with otherstars in the cluster for any planet to remain long inthe habitable zone.

(Source: Universe Today/Fraser Cain)


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In the big image at left, the many galaxies of a massive cluster called MACS J1149+2223 dominate the scene. Gravitational lensing by the giant clusterbrightened the light from the newfound galaxy, known as MACS 1149-JD, some 15 times. At upper right, a partial zoom-in shows MACS 1149-JD in moredetail, and a deeper zoom appears to the lower right. Credit: NASA/ESA/STScI/JHU


A simulation of the Eltanin strike.

Researchers examining sediments in the areadiscovered tiny grains of impact melt and debrisfrom meteorite fragments. Something big smashedthis spot.An asteroid strike on land is devastating, but anasteroid strike in the deep ocean is even worse.On both land and ocean, you get the plume ofwater vapor, sulfur, and dust blasted into the highatmosphere, raining molten rock down across awide area. But for asteroid strikes in the ocean,this is followed by a devastating tsunami thatinundates coastlines around the world. There arewaves hundreds of meters high at the crash site,and they travel deep inland on every coastline. Alocal event becomes a global event.But with the Eltanin meteor, this was followed by aprolonged ice age.Professor James Goff and his colleagues from theUniversity of New South Wales in Australia havebeen researching the Eltanin meteor and its after-effects. The timing of the impact seems to line upwith geologic deposits in Chile, Australia andAntarctica. Geologists traditionally connectedthese deposits with slower geological processes,like glaciation. But Goff and his team think thesedeposits might have been dropped all at once bythe devastating tsunami from Eltanin.Here’s a video that shows how the impact andsubsequent tsunami might have played out.Although the Earth was already thought to becooling in the mid to late Pliocene, the materialkicked into the high atmosphere by Eltanin couldhave pushed the planet’s climate past the tippingpoint:“There’s no doubt the world was already coolingthrough the mid and late Pliocene,” says co-authorProfessor Mike Archer. “What we’re suggesting isthat the Eltanin impact may have rammed thisslow-moving change forward in an instant - hurtlingthe world into the cycle of glaciations thatcharacterized the next 2.5 million years and tigge-

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Astronomers use redshift to describe cosmicdistances, and the ancient but newly-found galaxyhas a redshift, of 9.6. The term redshift refers tohow much an object’s light has shifted into longerwavelengths as a result of the expansion of theuniverse.Based on the Hubble and Spitzer observations,astronomers think the distant galaxy was less than200 million years old when it was viewed. It also issmall and compact, containing only about 1percent of the Milky Way’s mass. According toleading cosmological theories, the first galaxiesindeed should have started out tiny. They thenprogressively merged, eventually accumulatinginto the sizable galaxies of the more modernuniverse.The epoch of reionization refers to the period in thehistory of the Universe during which thepredominantly neutral intergalactic medium wasionized by the emergence of the first luminoussources, and these first galaxies likely played thedominant role in lighting up the Universe. Bystudying reionization, astronomers can learn aboutthe process of structure formation in the Universe,and find the evolutionary links between the smoothmatter distribution at early times revealed bycosmic microwave background studies, and thehighly structured Universe of galaxies and clustersof galaxies at redshifts of 6 and below.This epoch began about 400,000 years after theBig Bang when neutral hydrogen gas formed fromcooling particles. The first luminous stars and theirhost galaxies emerged a few hundred million yearslater. The energy released by these earliestgalaxies is thought to have caused the neutralhydrogen strewn throughout the Universe to ionize,or lose an electron, a state that the gas hasremained in since that time.


Did a Killer Asteroid Drive the Planet IntoAn Ice Age?

When a mountain-sized asteroid struck the deepocean off the coast of Antarctica 2.5 million yearsago, it set off an apocalyptic chain of events: adevastating rain of molten rock and then a deadlytsunami that inundated the coastlines of the PacificOcean. But according to a team of Australianresearchers, this was just the beginning. Thencame a protracted ice age that killed off many ofthe Earth’s large mammals.The Eltanin meteor, named after the USNS Eltaninwhich surveyed the area in 1964, is the onlyimpact that has ever been discovered in a deep-ocean basin. These deep water impacts must bemore common – so much of the planet is ocean -but they’re tricky to find because of theinaccessible depths of the impact craters.


that a singularity can be more subtle where just apatch of spacetime cannot be made to look locallyflat in any coordinate system.“Locally flat” refers to space that appears to be flatfrom a certain perspective. Our view of the Earthfrom the surface is a good example. Earth looksflat to a sailor in the middle of the ocean. It’s onlywhen we move far from the surface that thecurvature of the Earth becomes apparent.Einstein’s theory of general relativity begins withthe assumption that spacetime is also locally flat.Shockwaves create an abrupt change, ordiscontinuity, in the pressure and density of a fluid.This creates a jump in the curvature of spacetimebut not enough to create the “crinkling” seen in theteam’s models, Temple says.The coolest part of the finding for Temple is thateverything, his earlier work on shockwaves duringthe Big Bang and the combination of Vogler’s andReintjes’ work, fits together.There is so much serendipity,” says Temple. “Thisis really the coolest part to me.I like that it is so subtle. And I like that themathematical field of shockwave theory, created toaddress problems that had nothing to do withGeneral Relativity, has led us to the discovery of anew kind of spacetime singularity. I think this is avery rare thing, and I’d call it a once in ageneration discovery.”While the model looks good on paper, Temple andhis team wonder how the steep gradients inspacetime at a “regularity singularity” could causelarger than expected effects in the real world.General relativity predicts gravity waves might beproduced by the collision of massive objects, suchas black holes. “We wonder whether an explodingstellar shock wave hitting an imploding shock atthe leading edge of a collapse, might stimulatestronger than expected gravity waves,” Templesays. “This cannot happen in spherical symmetry,which our theorem assumes, but in principle itcould happen if the symmetry were slightlybroken.” (Source: Universe Today/John Williams)

SETI Astronomer Jill Tarter Recalls ‘Contact,’15 Years On

In 1985, famed astronomer, author and TV hostCarl Sagan invited Jill Tarter to dinner at his housenear Cornell University. Tarter, heavily involvedwith the Search for Extra-Terrestrial Intelligence,gladly accepted the chance to speak with Sagan, amember of SETI’s board of trustees. Seated withSagan and his wife, Ann Druyan, Tarter learnedthat Sagan had a fiction book on the go.“Annie said, ‘You may recognize someone in thebook, but I think you’ll like her,’” Tarter recalled inan interview with Universe Today.

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red our own evolution as a species.”It was this time of a global ice age that transitionedthe planet from the Pliocene to the Pleistocene. Itwas a bad time to be a Chalicothere orAnthracotheriidae, but a good time to be ahominid. So… thanks Eltanin.

(Source: Universe Today/Fraser Cain)

A Crinkle in the Wrinkle of Space-timeAlbert Einstein’s revolutionary general theory ofrelativity describes gravity as a curvature in thefabric of spacetime. Mathematicians at Universityof California, Davis have come up with a new wayto crinkle that fabric while pondering shockwaves.“We show that spacetime cannot be locally flat at apoint where two shockwaves collide,” says BlakeTemple, professor of mathematics at UC Davis.“This is a new kind of singularity in generalrelativity.”Temple and his collaborators study themathematics of how shockwaves in a perfect fluidaffect the curvature of spacetime. Their newmodels prove that singularities appear at the pointswhere shock waves collide. Vogler’s mathematicalmodels simulated two shockwaves colliding.Reintjes followed up with an analysis of theequations that describe what happens when theshockwaves cross. He dubbed the singularitycreated a “regularity singularity.”“What is surprising,” Temple told Universe Today,“is that something as mundane as the interactionof waves could cause something as extreme as aspacetime singularity - albeit a very mild new kindof singularity. Also surprising is that they form inthe most fundamental equations of Einstein’stheory of general relativity, the equations for aperfect fluid.”The results are reported in two papers by Templewith graduate students Moritz Reintjes and ZekeVogler in the journal Proceedings of the RoyalSociety A.Einstein revolutionized modern physics with hisgeneral theory of relativity published in 1916. Thetheory in short describes space as a four-dimensional fabric that can be warped by energyand the flow of energy. Gravity shows itself as acurvature of this fabric. “The theory begins with theassumption that spacetime (a 4-dimensionalsurface, not 2 dimensional like a sphere), is also“locally flat,” Temple explains. “Reintjes’ theoremproves that at the point of shockwave interaction, it[spacetime] is too “crinkled” to be locally flat.”We commonly think of a black hole as being asingularity which it is. But this is only part of theexplanation. Inside a black hole, the curvature ofspacetime becomes so steep and extreme that noenergy, not even light, can escape. Temple says


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Artist rendition of the unfurling of spacetime at the beginning of the Big Bang. Credit: John Williams/TerraZoom


“From her point of view, she was clear she wasn’tgoing to teach anyone astronomy. She wasinterested, in a personal way, about what thescientists were like,” Tarter said.When the crew was filming at the AreciboObservatory in Puerto Rico, Tarter flew there toobserve the work, meet with Foster and also showthe actress around. Tarter recalls bringing Fosterup in a cabin that had a perfect view of thetelescope, some 500 feet above the dish.Microphones and walkie-talkiesFilming was an interesting process for Tarter, aswell. There were the microphones, and the toolsthe crew used to check continuity. Most amusinglyfor Tarter, she observed Foster (reported height 5feet, 2 inches) needing to stand on a box for mostof the close-up shots with actor MatthewMcConaughey (reported as 6 feet tall).Two errors still irk Tarter today. There is a scenewhen Ellie gives a modified version of the DrakeEquation, which calculates the odds of intelligentlife who are capable of communicating with otherlife forms, and the calculations are all wrong. “It’sreally infuriating,” Tarter said.The other large mistake is a scene where Ellie getsa potential signal from space, while working at theKarl G. Jansky Very Large Array set of radiotelescopes in New Mexico.“She’s sitting in the middle of the array, in a car,with her laptop, and she gets the signal. And thefirst thing she does is pick up a walkie-talkie andstart broadcasting. That signal is going to wipe outthe signal from the sky. You don’t transmit bywalkie-talkie.”But overall, Tarter said the movie did a great job atportraying the feel of SETI. And Foster appreciatedTarter’s help. “She would write me handwrittenthank-you notes, which was a kind of manner thatmost people have lost. A great courtesy.”Hollywood outreachTarter walked the red carpet at the movie premiereand spent most of her time watching the film intears of happiness. That euphoria evaporatedwhen she saw the SETI Institute was not creditedat the end of the film. When she talked to one ofthe film producers, she said she was informed thatlawyers usually draft agreements specifying thelength of time the credit appears, and thecompensation received for doing so.“We don’t have a lawyer at the SETI Institute,” shesaid. “When I write a paper, I acknowledge mycollaborators. We got that wrong, so we never gotany credit. We might have gotten even morerecognition.”But the professional connection with Foster stillremains. Foster happily responded to a request

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SETI’s Jill Tarter. Credit: SETI

Suspecting the character was based on herself,Tarter’s response to Druyan was: “‘Just make sureshe doesn’t eat ice cones so much.’ It wassomething I was teased about.”Female, in a male-dominated fieldIt was 15 years ago this month that the movieContact, based on Sagan’s book of the same title,expanded to a run in international theatres after asuccessful summer in North America. The movieexplores the implication of aliens making contactwith Earth, but does it from more of a scientificperspective than most films.While Contact, the movie did not talk about the pisequences or advanced mathematical discussionsin Contact, the book, it did bring concepts such asprime numbers, interference with radio telescopes,and the religion vs. science debate to theatres in1997.Tarter, who has just retired as the long-timedirector of the SETI Institute, said she was stunnedby the parallels between her own life and that ofEllie Arroway, the character based on her inContact. Both lost parents at an early age. Bothalso had to make their way in a field aggressivelydominated by males. Tarter recalls a meeting withfellow female scientists of her generation someyears ago.“A huge percentage of us had been, in high school,either cheerleaders or drum majorettes. This is socounterintuitive, right? Because we’re the nerds,we’re the brainy ones … (it was because) we wereall competitors, and there weren’t any (female)sports to compete at. These sports were open, andwe competed, and we generally won.”Working on setTarter cautions the parallels did not totally match.The hopes and aspirations of Ellie in the book, andalso the movie, were products of Sagan’simagination. But the producers and actors of thefilm did want to get a close sense of what it waslike to work with SETI. After Jodie Foster was castas Ellie, there were multiple phone calls betweenthe actress and Tarter to discuss SETI.


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Solar shockwaves would have produced proto-planetary rings at different times, meaning the planets did not form simultaneously (artist concept).Credit: ESO


another half a million years on we would see thevery early stages of Mercury, Venus, Earth andMars.”The shockwaves emitted from the new-born Sunwould have rippled out material at different times,creating a series of debris rings around the Sunfrom which the planets formed.Abdylmayanov hopes that this research will helpus understand the development of planets arounddistant stars. “Studying the brightness of stars thatare in the process of forming could give indicationsas to the intensity of stellar shockwaves. In thisway we may be able to predict the location ofplanets around far-flung stars millions of yearsbefore they have formed.”


Researchers Present the Sharpest Image ofPluto Ever Taken from Earth

After taking a series of quick “snapshots” of Plutoand Charon using a recently-developed cameracalled the Differential Speckle Survey Instrument(DSSI), which was mounted on the GeminiObservatory’s 8-meter telescope in Hawaii,researchers combined them into a single imagewhile canceling out the noise caused by turbulenceand optical aberrations. This “speckle imaging”technique resulted in an incredibly clear, crispimage of the distant pair of worlds - especiallyconsidering that 1. it was made with images takenfrom the ground, 2. Pluto is small, and 3. Pluto isvery, very far away.Less than 3/4 the diameter of our Moon, Pluto (andCharon, which is about half that size) are currentlycircling each other about 3 billion miles from Earth- 32.245 AU to be exact. That’s a long way off, andthere’s still much more that we don’t know than wedo about the dwarf planet’s system. New Horizonswill fill in a lot of the blanks when it passes close byPluto in July 2015, and images like this can be abig help to mission scientists who want to makesure the spacecraft is on a safe path.In addition, the high resolution achievable throughthe team’s speckle imaging technique may also beused to confirm the presence of exoplanetcandidates discovered by Kepler. With anestimated 3- to 4-magnitude increase in imagingsensitivity, astronomers may be able to use it topick out the optical light reflected by a distantEarth-like world around another star.Speckle imaging has been used previously toidentify binary star systems, and with thecomparative ability to “separate a pair ofautomobile headlights in Providence, RI, from SanFrancisco, CA” there’s a good chance that it canhelp separate an exoplanet from the glare of itsstar as well.


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from Tarter to do voice-overs for a video clip usedfor a SETI high school curriculum for integratedscience. She also narrated a show, Life: A CosmicStory, for the California Academy of SciencesMorrison Planetarium.Tarter is now shifting into full-time outreach forSETI, saying the budgetary problems that shutdown the organization’s Allen Telescope Array forseveral months last year were a warning call.One of the organization’s newest initiatives isSETILive.org, which crowdsources analysis ofsignals from the Kepler Field. SETI solicits thepublic to take some time looking at the signalpatterns, one at a time, in search of extraterrestrialcommunications.“SETI is too important to allow it to fail,” Tartersaid, adding her focus is finding substantial, stablefunding from “that individual or institution that iscapable of taking a long view.”

(Source: Universe Today/Elizabeth Howell)

Planets in our Solar System May Have Formedin Fits and Starts

Did all the planets in our Solar System form atabout the same time? Conventional thinking saysthe components of our Solar System all formed atthe same time, and formed rather quickly. But newresearch indicates that a series of shockwavesemitted from our very young Sun may have causedthe planets to form at different times over millionsof years.“The planets formed in intervals - not altogether, aswas previously thought,” said Dr. TagirAbdylmyanov, Associate Professor from KazanState Power Engineering University in Russia.

Abdylmyanov’s research, which models themovements of particles in fluids and gasses and inthe gas cloud from which our Sun accreted,indicates that the first series of shockwaves duringshort but very rapid changes in solar activity wouldhave created the proto-planetary rings for Uranus,Neptune, and dwarf planet Pluto first. Jupiter,Saturn, and the asteroid belt would have comenext during a series of less powerful shockwaves.Mercury, Venus, Earth, and Mars would haveformed last, when the Sun was far calmer. Thismeans that our own planet is one of the youngestin the Solar System.

“It is difficult to say exactly how much time wouldhave separated these groups,” Abdylmyanov said,“but the proto-planetary rings for Uranus, Neptuneand Pluto would have likely formed very close tothe Sun’s birth. 3 million years later and we wouldsee the debris ring destined to form Saturn. Half amillion years after this we would see somethingsimilar but for Jupiter. The asteroid belt would havebegun to form about a million years after that, and


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A The first speckle reconstructed image for Pluto and Charon from which astronomers obtained not only the separation and position angle for Charon, but alsothe diameters of the two bodies. North is up, east is to the left, and the image section shown is 1.39 arcseconds across. Resolution of the image is about 20milliarcseconds rms. Credit: Gemini Observatory/NSF/NASA/AURA


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Hubble: Stunning New Deepest View Ever of the UniverseOh my! The Hubble Space Telescope has just outdone itself, taking the deepest-ever view of the Universe.But the new image really is a compilation of work over the past ten years, as the eXtreme Deep Field, orXDF was assembled by combining ten years of observations, with over 2 million seconds of exposure time,taken of a patch of sky in the center of the original Hubble Ultra Deep Field from 2004. The XDF is a smallfraction of the angular diameter of the full Moon.The new full-color XDF image is even more sensitive than the Hubble Ultra Deep Field image from 2004 andthe original Hubble Deep Field image from 1995. The new XDF image contains about 5,500 galaxies, evenwithin its smaller field of view. The faintest galaxies are one ten-billionth the brightness that the unaidedhuman eye can see.“The XDF is the deepest image of the sky ever obtained and reveals the faintest and most distant galaxiesever seen. XDF allows us to explore further back in time than ever before,” said Garth Illingworth of theUniversity of California at Santa Cruz, principal investigator of the Hubble Ultra Deep Field 2009 (HUDF09)program.Just take a look: magnificent spiral galaxies similar in shape to the Milky Way and Andromeda galaxies, aswell as large, fuzzy red and dead galaxies that are no longer producing stars. Peppered across the field aretiny, faint, and yet more distant galaxies that are like the seedlings from which today’s magnificent galaxiesgrew. The history of galaxies - from soon after the first galaxies were born to the great galaxies of today, likethe Milky Way - is laid out in this one remarkable image.Hubble was pointed at a tiny patch of southern sky in repeat visits made over the past decade with morethan 2,000 images of the same field taken with Hubble’s two primary cameras: the Advanced Camera forSurveys and the Wide Field Camera 3, which extends Hubble’s vision into near-infrared light. These werethen combined to form the XDF.The Universe is 13.7 billion years old, and incredibly, the XDF reveals galaxies that span back 13.2 billionyears in time. Most of the galaxies in the XDF are seen when they were young, small, and growing, oftenviolently as they collided and merged together.Astronomers are already planning to outdo this image. They are planning to aim the James Webb SpaceTelescope (at the XDF, and will study it with its infrared vision. The Webb telescope will find even faintergalaxies that existed when the Universe was just a few hundred million years old. Because of the expansionof the Universe, light from the distant past is stretched into longer, infrared wavelengths. The Webbtelescope’s infrared vision is ideally suited to push the XDF even deeper, into a time when the first stars andgalaxies formed and filled the early “dark ages” of the Universe with light.


Distances in the Hubble eXtreme Deep Field. Credit: Hubble


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The Hubble eXtreme Deep Field (XDF) combines Hubble observations taken over the past decade of a small patch of sky in the constellation of Fornax. With atotal of over two million seconds of exposure time, it is the deepest image of the Universe ever made.

Credit:: NASA, ESA, G. Illingworth, D. Magee, and P. Oesch (University of California, Santa Cruz), R. Bouwens (Leiden University), and theHUDF09 Team


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Hubble: Fireworks Erupt From Newborn StarHerbig-Haro (HH) objects come in a wide array of shapes, but the basic configuration stays the same. Twinjets of heated gas, ejected in opposite directions away from a forming star, stream through interstellar space.Astronomers suspect that these outflows are fueled by gas accreting onto a young star surrounded by a diskof dust and gas. The disk is the “fuel tank,” the star is the gravitational engine, and the jets are the exhaust.When these energetic jets slam into colder gas, the collision plays out like a traffic jam on the interstate. Gaswithin the shock front slows to a crawl, but more gas continues to pile up as the jet keeps slamming into theshock from behind. Temperatures climb sharply, and this curving, flared region starts to glow. These “bowshocks” are so named because they resemble the waves that form at the front of a boat.In the case of the single HH 110 jet, astronomers observe a spectacular and unusual permutation on thisbasic model. Careful study has repeatedly failed to find the source star driving HH 110, and there may begood reason for this: perhaps the HH 110 outflow is itself generated by another jet.Astronomers now believe that the nearby HH 270 jet grazes an immovable obstacle - a much denser, coldercloud core - and gets diverted off at about a 60-degree angle. The jet goes dark and then reemerges, havingreinvented itself as HH 110.The jet shows that these energetic flows are like the erratic outbursts from a Roman candle. As fast-movingblobs of gas catch up and collide with slower blobs, new shocks arise along the jet’s interior. The lightemitted from excited gas in these hot blue ridges marks the boundaries of these interior collisions. Bymeasuring the current velocity and positions of different blobs and hot ridges along the chain within the jet,astronomers can effectively “rewind” the outflow, extrapolating the blobs back to the moment when theywere emitted. This technique can be used to gain insight into the source star’s history of mass accretion.This image is a composite of data taken with Hubble’s Advanced Camera for Surveys in 2004 and 2005 andthe Wide Field Camera 3 in April 2011. (Source: Universe Today/Nancy Atkinson)

Just in time for summer fireworks season, the Hubble science team has released an image of Herbig-Haro 110, a young star with geysers of hot gasskyrocketing away through interstellar space. Twin jets of heated gas are being ejected in opposite directions from this star that is still in the formationprocess. The Hubble team says these outflows are fueled by gas falling onto the young star, which is surrounded by a disc of dust and gas. If the disc is thefuel tank, the star is the gravitational engine, and the jets are the exhaust. And even though the plumes of gas look like whiffs of smoke, they are actuallybillions of times less dense than the smoke from a fireworks display. Credit: Hubble


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LRO: Barnstorming the Moon’s Giordano Bruno CraterAt the 2012 Lunar Science Forum going on this week at the NASA Lunar Science Institute, scientist MarkRobinson presented some new stunning images from the Lunar Reconnaissance Orbiter’s cameras (LROC),including this oblique view Giordano Bruno crater, and a wonderful video (below) that allows viewers to“barnstorm” over the crater to witness the stark beauty of this impact basin.“I could spend weeks and months looking at the preserved materials in the crater,” Robinson said, addingthat views like this are helping scientists to understand the impact process. “Until astronauts visit GiordanoBruno, this gives a view about as close as you can get to standing on the surface to the west of the crater.”Robinson is the Principal Investigator for LROC, and in his talk today said all systems on LROC are workingnominally. “That’s NASA-speak for everything is fantastic,” he joked.With the wide angle camera, LROC has mapped the entire Moon nearly 33 times. “Every map has a differentphotometric geometry, so this is not a redundant dataset,” Robinson said, adding that the different lightingprovides different ways to study the Moon. “And to be able to do follow-up observations, I can’t tell you howgreat it is.”

Southern rim of Giordano Bruno crater seen obliquely by LROC. Credit: NASA/GSFC/Arizona State University


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Just about every month, the science team is able to take new mosaics of both the north and south pole, andthey’ve also found 160 pits - lunar caves - so far. These caves with “skylights” are intriguing because theywould offer potential protective habitats for future lunar explorers.Now in its extended mission, LRO is still going strong, and has provided incredible details of the lunarsurface. LRO project scientist Richard Vondrak said since the start of the mission, LRO has uploaded 325terabytes of data into the Planetary Data System, the digital storehouse for NASA science mission, throughJune 2012.“Thanks to LRO, the Moon’s topography is now better understood than the Earth, since two-thirds of Earth iscovered by water,” Vondrak said.But both scientists agrees LRO is just getting started.“The Moon is one of the most engaging bodies in the Solar System and we’ve still got a lot of work to do,”Robinson saidRobinson suggests scrolling through all of the details of this beautiful impact crater by looking at the full-resolution version of Giordano Crater “not to be missed!” he said.Caption: Southern rim of Giordano Bruno crater seen obliquely by LROC. Credit: NASA/GSFC/Arizona StateUniversityAt the 2012 Lunar Science Forum going on this week at the NASA Lunar Science Institute, scientist MarkRobinson presented some new stunning images from the Lunar Reconnaissance Orbiter’s cameras (LROC),including this oblique view Giordano Bruno crater, and a wonderful video (below) that allows viewers to“barnstorm” over the crater to witness the stark beauty of this impact basin.“I could spend weeks and months looking at the preserved materials in the crater,” Robinson said, addingthat views like this are helping scientists to understand the impact process. “Until astronauts visit GiordanoBruno, this gives a view about as close as you can get to standing on the surface to the west of the crater.”Robinson is the Principal Investigator for LROC, and in his talk today said all systems on LROC are workingnominally. “That’s NASA-speak for everything is fantastic,” he joked.With the wide angle camera, LROC has mapped the entire Moon nearly 33 times. “Every map has a differentphotometric geometry, so this is not a redundant dataset,” Robinson said, adding that the different lightingprovides different ways to study the Moon. “And to be able to do follow-up observations, I can’t tell you howgreat it is.”Just about every month, the science team is able to take new mosaics of both the north and south pole, andthey’ve also found 160 pits - lunar caves - so far. These caves with “skylights” are intriguing because theywould offer potential protective habitats for future lunar explorers.Now in its extended mission, LRO is still going strong, and has provided incredible details of the lunarsurface. LRO project scientist Richard Vondrak said since the start of the mission, LRO has uploaded 325terabytes of data into the Planetary Data System, the digital storehouse for NASA science mission, throughJune 2012.“Thanks to LRO, the Moon’s topography is now better understood than the Earth, since two-thirds of Earth iscovered by water,” Vondrak said.But both scientists agrees LRO is just getting started.“The Moon is one of the most engaging bodies in the Solar System and we’ve still got a lot of work to do,”Robinson saidRobinson suggests scrolling through all of the details of this beautiful impact crater by looking at the full-resolution version of Giordano Crater “not to be missed!” he said. (Source: Universe Today/Nancy Atkinson)


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Close-up detail of the rim of Giordano Crater. Credit: NASA/GSFC/Arizona State University


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Hubble: The Last Outbursts of a Dying StarAs stars approach the inevitable ends of their lives they run out of stellar fuel and begin to lose agravitational grip on their outermost layers, which can get periodically blown far out into space in enormousgouts of gas - sometimes irregularly-shaped, sometimes in a neat sphere. The latter is the case with the starabove, a red giant called U Cam in the constellation Camelopardalis imaged by the Hubble SpaceTelescope.U Cam is an example of a carbon star. This is a rare type of star whose atmosphere contains more carbonthan oxygen. Due to its low surface gravity, typically as much as half of the total mass of a carbon star maybe lost by way of powerful stellar winds. Located in the constellation of Camelopardalis (The Giraffe), nearthe North Celestial Pole, U Cam itself is actually much smaller than it appears in Hubble’s picture. In fact, thestar would easily fit within a single pixel at the center of the image. Its brightness, however, is enough tosaturate the camera’s receptors, making the star look much bigger than it really is.The shell of gas, which is both much larger and much fainter than its parent star, is visible in intricate detailin Hubble’s portrait. While phenomena that occur at the ends of stars’ lives are often quite irregular andunstable, the shell of gas expelled from U Cam is almost perfectly spherical. (Source: UT/Jason Major)

Credit: Hubble


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Hubble: Tiny, Ancient ‘Ghost Galaxies’They’re out there; tiny, extremely faint and incredibly ancient dwarf galaxies with so few stars that scientistscall them ‘ghost galaxies.’ NASA’s Hubble Space Telescope captured images of three of these small-frygalaxies in hopes of unravelling a mystery 13 billion years in the making.Astronomers believe these tiny, ghost-like galaxies spotted alongside the Milky Way Galaxy are among theoldest, tiniest and most pristine galaxies in the Universe. Hubble views reveal that their stars share the samebirth date. The galaxies all started forming stars more than 13 billions years ago but then abruptly stoppedwithin just one billion years after the Universe was born.“These galaxies are all ancient and they’re all the same age, so you know something came down like aguillotine and turned off the star formation at the same time in these galaxies,” said Tom Brown of the SpaceTelescope Science Institute in Baltimore, Md., the study’s leader. “The most likely explanation isreionization.”Reionization of the Universe began in the first billion years after the Big Bang. During this time, radiationfrom the first stars knocked electrons off hydrogen atoms, ionizing the hydrogen gas. This process alsoallowed hydrogen gas to become transparent to ultraviolet light. This same process may also havesquashed star-making in dwarf galaxies, such as those in Brown’s study. These galaxies are tiny cousins tostar-making dwarf galaxies near the Milky Way. And because of their small size, just 2,000 light-yearsacross, they were not massive enough to shield themselves from the harsh ultraviolet light of the earlyUniverse which stripped away their meager supply of hydrogen gas, leaving them unable to make new stars.Astronomers proposed many reasons for the lack of stars in these galaxies in addition to the reioniationtheory. Some scientists believed internal events such as supernovae blasted away the gas needed to createnew stars. Others suggested that the galaxies simply used up their supply of hydrogen gas needed to makestars.

These Hubble images show the dim, star-starved dwarf galaxy Leo IV. The image at left shows part of the galaxy, outlined by the white rectangular box. Thebox measures 83 light-years wide by 163 light-years long. The few stars in Leo IV are lost amid neighboring stars and distant galaxies. A close-up view of thebackground galaxies within the box is shown in the middle image. The image at right shows only the stars in Leo IV. The galaxy, which contains severalthousand stars, is composed of sun-like stars, fainter, red dwarf stars, and some red giant stars brighter than the sun.

Credit: NASA, ESA, and T. Brown (STScI)


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Brown measured the stars’ ages by looking at their brightness and colors. The stellar populations in thesefossil galaxies range from a few hundred to a few thousand stars; some sun-like, some red dwarfs and somered stars larger than our Sun. When evidence showed that the stars were indeed ancient, Brown enlisted thehelp of Hubble’s Advanced Camera for Surveys to burrow deep within six galaxies to determine when theywere born. So far, the team has finished analyzing data for three; Hercules, Leo IV and Ursa Major. Thegalaxies lie between 330,000 light-years to 490,000 light-years. For comparison, Brown compared thegalaxies’ stars with those found in M92, a 13 billion-year-old globular cluster located about 26,000 light-yearsfrom Earth. He found they are of similar age.“These are the fossils of the earliest galaxies in the universe,” Brown said. “They haven’t changed in billionsof years. These galaxies are unlike most nearby galaxies, which have long star-formation histories.”Brown’s discovery could help explain the so-called “missing satellite problem.” Astronomers have observedonly a few dozen dwarf galaxies around the Milky Way while computer simulations predict thousands shouldexist. But perhaps they do exist. The Sloan survey found more than a dozen tiny, star-starved galaxies in theMilky Way’s neighborhood while scanning just a portion of the sky. Astronomers think that dozens moreultra-faint galaxies may lurk undetected with the possibility of thousands of even smaller dwarfs containingvirtually no stars.The tiny galaxies may be star-deprived but they still have an abundance of dark matter, the framework uponwhich galaxies are built. Normal dwarf galaxies near the Milky Way Galaxy contain ten times more darkmatter than ordinary visible matter. Brown explains that these tiny galaxies are now islands of mostly darkmatter, unseen for billions of years until astronomers began finding them in the Sloan Survey.


These computer simulations show a swarm of dark matter clumps around our Milky Way galaxy. Some of the dark-matter concentrations are massive enoughto spark star formation. Thousands of clumps of dark matter coexist with our Milky Way galaxy, shown in the center of the top panel. The green blobs in themiddle panel are those dark-matter chunks massive enough to obtain gas from the intergalactic medium and trigger ongoing star formation, eventuallycreating dwarf galaxies. In the bottom panel, the red blobs are ultra-faint dwarf galaxies that stopped forming stars long ago.

Credit: NASA, ESA, and T. Brown and J. Tumlinson (STScI)


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Hubble: Fifth Moon Found Around PlutoThis just in! Astronomers working with the Hubble Space Telescope have spotted a new moon arounddistant Pluto, bringing the known count up to 5. The image above was released by NASA just minutes ago,showing the Pluto system with its newest member, P5. This news comes just a couple of weeks shy of theone-year anniversary of the announcement of Pluto’s 4th known moon, still currently named “P4″.The newswas shared this morning by an undoubtedly excited Alan Stern of the Southwest Research Institute (SwRI)on Twitter. Astronomers estimate P5 to be between 6 and 15 miles (9.6 to 24 km) in diameter. It orbits Plutoin the same plane as the other moons - Charon, Nix, Hydra and P4.“The moons form a series of neatly nested orbits, a bit like Russian dolls,” said team lead Mark Showalter ofthe SETI Institute. A mini-abstract of an upcoming paper lists image sets acquired on 5 separate occasionsin June and July. According to the abstract, P5 is 4% as bright as Nix and 50% as bright as P4.The new detection will help scientists navigate NASA’s New Horizons spacecraft through the Pluto system in2015, when it makes an historic and long-awaited high-speed flyby of the distant world.


The satellite’s mean magnitude is V = 27.0 +/- 0.3, making it 4 percent as bright as Pluto II (Nix) and half as bright as S/2011 (134340) 1. The diameterdepends on the assumed geometric albedo: 10 km if p_v = 0.35, or 25 km if p_v =0.04. The motion is consistent with a body traveling on a near-circularorbit coplanar with the other satellites. The inferred mean motion is 17.8 +/- 0.1 degrees per day (P = 20.2 +/- 0.1 days), and the projected radial distancefrom Pluto is 42000 +/- 2000 km, placing P5 interior to Pluto II (Nix) and close to the 1:3 mean motion resonance with Pluto I (Charon). Credit: Hubble


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Catchers of the Light -A History of Astrophotography

by Stefan Hughes

Available from: www.catchersofthelight.com

Every day our eyes catch the light of ourmemories - time spent with family, the journey towork, a special holiday, a beautiful sunset or adark starlit night. Each image captured is apicture drawn in light - a photograph: only to belost in our minds or forever forgotten. Nearly twohundred years ago a small group of amateurscientists achieved what had eluded mankind forcenturies - the ability to capture a permanentrecord of an image seen by their own eyes - amoment in time frozen onto a surface. They haddiscovered Photography. They were the‘Catchers of the Light’.‘Catchers of the Light’ is the first comprehensiveand fully researched History of Astrophot-ography. It begins with the work of the earlypioneers of photography; then tells the story ofthe first astronomical photographs of the Moonand Sun; of the race between nations to be thefirst to ‘capture’ a total solar eclipse; and theproblems encountered by astronomers whenattempting to image the Planets and other bodiesof our Solar System.

Recent Interferometry Applications inTopography and Astronomy,

by Ivan Padron, Publisher: InTeO, 2012,229 pages, ISBN: 9535104049

Available from: amazon.com

This book provides a current overview of thetheoretical and experimental aspects of someinterferometry techniques applied to Topographyand Astronomy. Each chapter offers anopportunity to expand the knowledge aboutinterferometry techniques and encourageresearchers in development of newinterferometry applications.The first two chapters comprise interferometrytechniques used for precise measurement ofsurface topography in engineering applications;while chapters three through eight are dedicatedto interferometry applications related to Earth'stopography.The last chapter is an application of interferomet-ry in Astronomy, directed specifically todetec-tion of planets outside our solar system.


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The Early Years of Radio Astronomyby W. T. Sullivan, Publisher: Cambridge

University Press, 1984, 416 Pages,ISBN: 052125485X

Radio astronomy has revolutionized the courseof modern astronomy. Marking the fiftiethanniversary of Jansky's discovery in 1933 ofextraterrestrial radio emission, Professor Sullivanasked many of the pioneers in the field to setdown their versions of events and the peoplewho made them. Each of the score ofcontributors seeks to give a good 'feeling' for thetimes to the great majority of readers who will nothave experienced them. Over 150 illustrations,mostly historical photographs of men andmachines, enliven the various recollections andreflections. The list of contributors includes manyof the key personalities and covers all the majorlaboratories and countries involved in radioastronomy before 1960. In addition to the radioastronomers themselves, there are contributionsfrom optical astronomers and theorists closelyrelated to the field, as well as historians oftwentieth century astronomy.


Astronomy: Understanding the Universeby Sherman Hollar,

Publisher: Rosen Education Service,2011, 96 pages, ISBN: 1615305203

Fathoming the boundlessness of space and theuniverse, we are immediately filled with curiosityabout our own origins and wonder about theobjects, life forms, and matter that populate thecosmos. Through the observations and work ofastronomers over time, we have slowly been ableto reduce the number of unknowns and developexplanations or theories for some of the celestialobjects and phenomena we see. This space-traveling survey recounts some of the majordiscovery milestones in the field of astronomyand examines the tools and techniques currnt-ly used by astronomers to study the univer-se.


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Kepler's Philosophy and the New Astronomyby Rhonda Martens, Princeton University Press,

2000, 216 pages, ISBN: 0691050694

Johannes Kepler contributed importantly to everyfield he addressed. He changed the face ofastronomy by abandoning principles that hadbeen in place for two millennia, made importantdiscoveries in optics and mathematics, and wasan uncommonly good philosopher. Generally,however, Kepler's philosophical ideas have beendismissed as irrelevant and even detrimental tohis legacy of scientific accomplishment. Here,Rhonda Martens offers the first extended study ofKepler's philosophical views and shows howthose views helped him construct and justify thenew astronomy.

Martens notes that since Kepler became aCopernican before any empirical evidencesupported Copernicus over the entrenchedPtolemaic system, his initial reasons forpreferring Copernicanism were not telescopeobservations but rather methodological andmetaphysical commitments. Further, she showsthat Kepler's metaphysics supported the strikinglymodern view of astronomical method that led himto discover the three laws of planetary motionand to wed physics and astronomy a keydevelopment in the scientific revolution.By tracing the evolution of Kepler's thought in hisastronomical, metaphysical, and epistemological

works, Martens explores the complex interplaybetween changes in his philosophical views andthe status of his astronomical discoveries. Sheshows how Kepler's philosophy paved the wayfor the discovery of elliptical orbits and provided adefense of physical astronomy's methodologicalsoundness. In doing so, Martens demonstrateshow an empirical discipline was inspired andprofoundly shaped by philosophical assump-tions.

From Eudoxus to Einstein: A History ofMathematical Astronomy

by C. M. Linton,Publisher: Cambridge University Press, 2004,

529 pages, ISBN: 0521827507

Since humans first looked towards the heavens,they have attempted to predict and explain themotions of the sun, moon, and planets. This bookdescribes the theories of planetary motion thathave been developed through the ages, from thehomocentric spheres of Eudoxus to Einstein'sgeneral theory of relativity. It emphasizes theinteraction between progress in astronomy and inmathematics, demonstrating how the two havebeen inextricably linked since Babyloniantimes. This valuable text is accessible to a wideaudience, from amateur astronomers toprofessional historians of astronomy.



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Basic Optics for the Astronomical Sciencesby James B. Breckinridge, SPIE Press Book,

ISBN: 9780819483669, 448 pagesThis text was written to provide students ofastronomy and engineers an understanding ofoptical science the study of the generation,propagation, control, and measurement of opticalradiation as it applies to telescopes andinstruments for astronomical research in theareas of astrophysics, astrometry, exoplanetcharacterization, and planetary science. Thebook provides an overview of the elements ofoptical design and physical optics within theframework of the needs of the astronomicalcommunity.Features of this text include: an historical perspective on the

development of telescopes and theirimpact on our understanding of theuniverse

a review of the optical measurementsthat astronomers record, andidentification of the attributes for groundand space observations

presentation of the fundamentals ofoptics, such as image location and size,geometrical image quality, imagebrightness, scalar diffraction and imageformation, interference of light, andradiometry

discussion of the role of partialcoherence in image formation andfactors that affect image quality, as wellas the role of optical metrology andwavefront sensing and control inastronomical telescopes

presentation of the fundamentals ofoptics, such as image location and size,geometrical image quality, imagebrightness, scalar diffraction and imageformation, interference of light, andradiometry

investigations of segmented telescopesand their applications and performancemetrics, sparse-aperture telescopes, andthe optical challenges of designing andbuilding telescopes or instruments fordetecting and characterizing exoplanets

PREFACEAstronomical science advances use the followingresearch cycle: measure parts of the universe,develop theories to explain the observations, usethese new theories to forecast or predictobservations, build new telescopes andinstruments, measure again, refine the theories ifneeded, and repeat the process. Critical to thesuccess of this cycle are new observations,which often require new, more sensitive, efficientastronomical telescopes and instruments.Currently, the field of astronomy is undergoing arevolution. Several new important optical/infraredwindows into the universe are opening as a resultof advances in optics technology, includingsystems using high angular resolution, very highdynamic range, and highly precise velocity andposition measurements. High-angular-resolutionsystems, which incorporate adaptive optics andinterferometry, promise gains of more than 104 inangular resolution on the sky above our currentcapabilities. Advanced coronagraphs enable veryhigh-dynamic-range systems that enableastronomers to image an exoplanet in thepresence of the blinding glare from its parent starthat is more than 1012 times brighter.Optical science is the study of the generation,propagation, control, and measurement of opticalradiation. The optical region of the spectrum isconsidered to range across the wavelengthregion of ~0.3 to ~50 μm, or from the UV throughthe visual and into the far infrared. Differentsensors or detectors are used for coveringsections of this broad spectral region. However,the analysis tools required to design, build, align,test, and characterize these optical systems arecommon: geometrical raytracing, wavefront abe-


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rration theory, diffraction theory, polarization,partial coherence theory, radiometry, and digitalimage restoration. Advances in allied disciplinessuch as material science, thermal engineering,structures, dynamics, control theory, andmodeling within the framework of the tolerancesimposed by optics are essential for the nextgeneration of telescopes.This text provides the background in optics togive the reader insight into the way in whichthese new optical systems are designed,engineered, and built. The book is intended forastronomy and engineering students who want abasic understanding of optical systemengineering as it is applied to telescopes andinstruments for astronomical research in theareas of astrophysics, astrometry, exoplanetcharacterization, and planetary science. Giantground-based optical telescopes such as theGiant Segmented Mirror Telescope, the ThirtyMeter Telescope, and the Extremely LargeTelescope are currently under development. TheJames Webb Space Telescope is underconstruction, and the Space InterferometerMission has successfully completed itstechnology program. The astronomical sciencesare, indeed, at the threshold of many newdiscoveries.Chapter 1 provides an historical perspective onthe development of telescopes and their impacton our understanding of the universe. Chapter 2reviews the optical measurements astronomersrecord and identifies the attributes for ground andspace observatories. Chapter 3 provides thetools used for obtaining image location, size, andorientation and presents the geometricalconstraints that need to be followed to maximizethe amount of radiation passed by the system.Chapter 4 presents geometrical aberration theoryand introduces the subject of image quality.Chapter 5 provides methods to maximize theamount of radiation passing through the opticalsystem: transmittance, throughput, scatteredlight, and vignetting. Chapter 6 provides a basicintroduction to radiative transfer through anoptical system and identifies several factorsneeded to maximize the signal-to-noise ratio.Chapter 7 provides an introduction to the opticsof the atmosphere necessary for ground-basedastronomers. Chapter 8 introduces the scalarand vector wave theories of light and identifiessources of instrumental polarization that willaffect the quality of astronomical data.Using the Fourier transform, Chapter 9 providesan in-depth analysis of the propagation of scalarwaves through an optical system as the basis ofa discussion on the effects of astronomical tele-

scopes and instruments on image quality.Chapter 10 provides a discussion ofinterferometry within the framework of partialcoherence theory. The Fourier transformspectrometer, the Michelson stellarinterferometer, and the rotational shearinterferometer are used as examples and areanalyzed in detail. Chapter 11, coauthored withSiddarayappa Bikkannavar, discusses theimportant new role that optical metrology andwavefront sensing and control play in the designand construction of very large ground- andspace-based telescopes.These 11 chapters have formed the basis of theOptical System Engineering class given by theauthor at CALTECH. Chapter 12 provides ananalysis that is fundamental to the understandingof segmented-aperture telescopes and how theyenable the next-generation, very large ground-and space-based telescopes. Chapter 13presents an analysis of sparse-aperturetelescopes, describes how they are used forextremely high angular resolution, and identifiestheir limitations. Chapter 14 discussesastrometric and imaging interferometry within theframework of basic optics. Chapter 15 developsbasic concepts for extreme-contrast systemssuch as coronagraphs for the characterization ofexoplanet systems.

James B. BreckinridgePasadena, California

April 2012


Caroli and Albireo. Even Collinder 399 – the “CoatHanger” showed pleasing red hints! Again, I wasvery appreciative of the drive unit when trying tosplit Epsilon Lyrae. With smaller aperture, the f/11focal ratio could handle it - but again, needed themoment of perfect steadiness to say it was a cleansplit. No offense, but both the included 3X barlowand 4mm eyepiece are simply too muchmagnification for this scope to handle. (But a nice10mm Plossl sure fills the bill!)As for the scope itself, you’ll find it feels very“healthy”. The focuser isn’t a Feathertouch, but ithas a nice feel to it… positive and it doesn’t sloparound with a heavier eyepiece in it. The included5×24 finderscope might seem a little small to mostobservers, but I liked it for two reasons - it’s anoptical finderscope and it’s appropriately sized towhat the scope can achieve. It’s just enough to pickoff fainter “star hop” marker stars and give a hint ofbrighter objects. The included 1.25″ diagonal is alsoquite satisfactory and the 20mm eyepiece is theperfect workhorse for the majority of observations.You would be impressed with the crisp quality of theviews of the Double Cluster, the ethereal WildDucks and the slightly pincushion look of M2.Next up? Try kicking in better eyepieces and you’llsurprise yourself. Without getting brand specific, ahigher dollar Plossl and a high magnification ED.Surprise, surprise! Here again, Celestrontelescopes show their optical quality as the view didimprove. After having become so accustomed tofast telescopes, it was a real pleasure to work witha longer focal ratio and see just how far I couldpush it. The Celestron Powerseeker 80 is definatelydeserving of higher quality eyepieces and adiagonal. All in all, this is an inexpensive telescopethat is well made and, with care, should last throughyears of observing. You some day may end up witha little duct tape here and there… But it’s got soul.My thanks go to Optics Planet for their generousdonation of the Celestron Powerseeker 80EQ to ourannual star party/fundraiser at Warren RuppObservatory. (Source: Universe Today/Tammy Plotner)

PowerSeeker 80 has surprisingly good optics as you can see from this closeup view of a fault line known as the straight wall.

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DDid you ever have a T-shirt that you reallyenjoyed and wore until you wore it out? How abouta favorite pair of slippers? You know, the ones withthe duct tape soles? Then I think you’re going tofeel the same way about this telescope. It’s darnnear the perfect combination of power, portabilityand price. Just right for casual observing… Be it ona rooftop or from your suburban yard. What makesit even more attractive is its ability to track itssubject matter!What’s new on the Tammy-testing homefront? Thistime it’s an Optics Planet Celestron PowerSeeker80EQ refractor telescope. With 80mm of apertureand a 900mm focal length, it is not a small tube. Itis elegant in both lines and size and does notappear “spindly”. Unlike most small aperturerefractors which favor the alt/az, it comes with alight weight equatorial mount with a delightfuladdition - a drive unit. This means this specialedition PowerSeeker 80EQ is going to make yourtime with lunar and planetary studies much morepleasant, and make higher magnification muchmore user-friendly.Assembly is quite easy and fairly intuitive if you arefamiliar with telescopes and equatorial mounts.One thing you will very much enjoy is how easy itis to handle - a manageable 19 lbs. (8.62 kg) totalweight. This means it is light enough to be set upcomplete and ready to be set outside the door at amoment’s notice. (This is something that I verymuch enjoy and approve of in a telescope. While Ifind large aperture to be breathtaking and Idemand it for serious study, I also want atelescope that’s on hand for a quick look at theMoon or a joyous half hour with a planet.) While alight weight mount is super, don’t forget you’remaking a trade-off. It’s not going to support heavycamera equipment and it’s not going to take a lotof abuse, such as overtightening or stressing gearsthrough imbalance. However, it is quite capable ofadding on certain types of imaging equipment,such as a webcam or eyepiece camera, orpiggybacking a smaller camera on the mountingrings.Next up? The view. As always, Celestron comesthrough with quality optics. At 80mm you’re notgoing to be getting Hubble images, but brightobjects are crisp and clean. The views of Saturnand Mars were quite satisfactory and thanks to theincluded drive unit, the Celestron Powerseeker80EQ delivered a whisper of the Cassini divisionand the neat little apparition of Titan swingingaround the outside. Even Mars was capable ofshowing some dark patches when the atmosphereheld still! Unfortunately, there wasn’t any Moon atthe time, but I was very pleased with the colorcorrection on beautiful double stars such as Cor


Powerseeker 80EQ Refractor Telescope

The planet Jupiter, image captured with PowerSeeker 80 telescope, Celestron NexImage and 2x barlow.

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“Andrew Ainslie Common was a pioneer in theconstruction of large silvered mirror telescopes. Heshowed the potential of such instruments tophotograph the heavens provided they wereaccurately driven. Two of his telescopes are still inoperation today. He was one of the greatAstrophotographers”Procedures & TechniquesAndrew Ainslie Common was without doubt one ofthe great pioneers of Astrophotography, notparticularly because of the photographs he took; infact he took very few during the course of hislifetime. His chief claim to fame lies in thetechniques and procedures he used to capturethem, but even more importantly in the telescopeshe constructed and designed specifically for DeepSky Astrophotography.His legacy lives on today, for two of the greatreflecting telescopes he constructed over a centuryago, are still in use and helping us understand theuniverse in which Andrew Common first gazedupon so long ago. Let us now turn the pages ofhistory back over 150 years to a world far differentfrom the one fate decreed Andrew AinslieCommon would follow.Newcastle-upon-TyneAndrew Ainslie Common was born on the 7thAugust 1841 in Oxford Street, in the parish of St.Andrew’s, Newcastle-upon-Tyne, the second of thethree children of Thomas Common, a surgeon ofthat city, and his wife Mary (nee Hall).The area of Newcastle where Andrew Commonwas born was at the time a new residential area onthe outskirts of the city. The empty spaces around

Andrew Ainslie Common was without doubtone of the great pioneers ofAstrophotography. His chief claim to famelies, not particularly because of thephotographs he took, but in the techniquesand procedures he used to capture them, andeven more importantly in the telescopes heconstructed and designed specifically forDeep Space Astrophotography…

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his home were soon to disappear as the city’spopulation rapidly expanded in the coming years;as is evident from the map which shows theominous presence of land allocated for newbuildings in 1843. It maybe thought that Andrewwas immune from the poverty, disease anddepravation that many tens of thousands in the citywere accustomed to. This was far from being thecase, indeed the opposite was true.His father, Thomas Common was a respected andwell known surgeon in the North of England, beingone of the early pioneers in the field of eyecataract surgery. He had qualified as a Surgeonand Apothecary, becoming a member of the RoyalCollege of Surgeons in 1832, aged 22. Hesubsequently trained other Apprentice Surgeons,who later would make great contributions tohelping the poor, sick and needy in the city; themost well known being Dr. Charles John Gibb, the

Andrew Ainslie Common (1841 - 1903)


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Born: 7th of August 1841, Newcastle-upon-Tyne, Northumberland, England. Died: 2nd of June 1903, Ealing, Middlesex, England. Andrew Ainslie Commonwas without doubt one of the great pioneers of Astrophotography. His chief claim to fame lies, not particularly because of the photographs he took, but inthe techniques and procedures he used to capture them, and even more importantly in the telescopes he constructed and designed specifically for DeepSpace Astrophotography. Two of his telescopes are still in operation today, the 36-inch ‘Crossley’ reflector at the Lick Observatory in California and the 60-inch ‘Rockefeller’ reflector at the Boyden Observatory, Bloemfontein, South Africa.

He believed that the telescopes of the future should be silvered mirrored reflectors and not the ‘Great Refractors’ which at that time, were to be foundunder the domes all the ‘Great Observatories’ of the world. Furthermore, if they were to be of any use to astronomers, they should be on a stable platformof ‘such, a construction of mounting as to give the greatest mount of steadiness with the least amount of motion’; provided with a ‘Driving clock. Circles tofind or identify an object and motions taken to eye end’ and most important of all ‘a suitable locality for the erection of the telescope’.

Added by the Editor


All Saints Church, Newcastle, Andrew Common was baptised here 2ndSeptember 1841.

Charles Gibb Indenture 1st July 1841 – Apprentice to Thomas Common,Surgeon.

Jane (nee Anderson) had six daughters includingMary and three brothers. It was also a knit closefamily who also possessed tremendous businesssense. In 1841, Mary’s two brothers George andWalter lived with Thomas and Mary Common atOxford Street, Newcastle; whilst her other brotherMatthew Hall was fully occupied with his businessactivities - something which he never stoppeddoing.

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House Surgeon at the Newcastle Infirmary.As a young boy growing up in Newcastle with hisbrother John and his sister Mary, he was alwaysaware of the fragility of life. His father’s professionmust have been a constant reminder to him of thishard lesson. The city of Newcastle had during theperiod 1831 to 1853 suffered a number of choleraepidemics caused by poor sanitation and thepresence of much slum housing.In 1842, the year following Andrew’s birth hisfather was appointed the resident surgeon at thenearby Gateshead Dispensary. The GatesheadDispensary was established in 1832 as a directconsequence of the cholera the previous year. Itspurpose was to provide free medical care to thoseunable to pay for it - the poor and the deprived. Asis always the way it was too little too late - thecholera outbreak of 1831 had already killed 306people. It had taken this shock treatment for the‘great and the good’ of Gateshead to be stirred intoaction!MorpethThomas and Mary Common tried as best theycould to shield their young children from the livesof those less fortunate from themselves andperhaps to avoid bringing sickness on them. As aresult of this concern the family moved from thecity of Newcastle itself and Thomas Common’swork, to the more pleasant surrounding of themarket town of Morpeth. By the time of the 1851Census the family are to be found living at No. 16Newgate Street, although Thomas Common wasnot at home, but visiting a fellow surgeon Mr.Frederick Beavan at his home in Shotley.Andrew Common was about ten years old when hefirst became interested in Astronomy; and oftenused a telescope his mother had borrowed from ayoung surgeon called John Pickering Bates; whoseparents John and Isabella Bates owned thegrocer’s shop at No. 94 Newgate Street, just upthe road from where they lived. However, AndrewCommon’s newly found passion for Astronomywas abruptly and tragically put on hold.In about 1852 Thomas Common died, leaving hisfamily in poor financial circumstances, but notdestitute. It is known that Mary Common was inreceipt of annuities as is evident from the 1851Census which lists her as married with the addedstatus of ‘Annuitant’. Furthermore, Mary Commonhad two other things going for her - firstly, the helpand support she received from her three brothers -Matthew, George and Walter Hall; and secondlythe sheer determination and resourcefulness of herown children.The Hall family into which Mary was born was alarge one. Her f ather Walter Hall and her mother


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Top: Gateshead Dispensary, Nelson Street, (1832 – 1946) Plaque. Bottom: Gateshead Dispensary, Nelson Street (built 1855), c1890.


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Top: Newgate Street, Morpeth, c1890. Bottom: Tynemouth, Northumberland, c1890.


Appointment of Thomas Common as Surgeon at Gateshead DispensaryMay 1842.

Tynemouth Place, Tynemouth.

Millers at Gayton Mill (1836 – 1937).

become part of his character, and which heexhibited throughout the rest of his life. He waswell known for both his great physical and mentalstrength, as well a great ability to enjoy life to thefull.A number of examples of this were recounted inhis obituary which appeared in the ‘Observatory’

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It is not known what type of education Andrew andhis siblings received or the length of time it lasted,but it is clear that they were educated children,who would in later life make something ofthemselves. Andrew’s elder brother John FreelandFergus Common was to make his career as anIron Ship Builder and later on as a Naval Architect;whilst his younger sister Mary Jane married in1878 Henry Austen Hensman a sanitary engineerfrom London.TynemouthShortly after her husband’s death, Mary Commonmoved her family to the picturesque coastal townof Tynemouth to live with her younger brotherGeorge Hall, the manager of a local White LeadWorks.It is possible that whilst living in Tynemouth, youngAndrew renewed his acquaintance with thetelescope he had grown fond of in Morpeth. JohnPickering Bates its owner had by 1855 qualified asa surgeon, and had set up his practice at No. 15Saville Street in Tynemouth. He later married inTynemouth and continued working there as asurgeon until his retirement in about 1879, whenhe moved back to Morpeth.By the time of the 1861 Census Mary Common isfound living at her brother’s house at No. 8Tynemouth Place, Tynemouth with her eldest sonJohn and her daughter Mary Jane, but no sign ofAndrew Ainslie Common.GaytonAndrew first known employment was working withhis uncle Walter Hall. Sometime before 1850,Walter Hall, a baker by trade met a young ladycalled Mary Anne Matthews, the daughter ofRobert Matthews a miller from the village ofGayton in Norfolk. Robert Matthews a widower hadin 1845 married Andrew’s Aunt Margaret Chapman(nee Hall) the widow of Jasper John Chapman.Walter Hall married Mary Anne Matthews in 1850and moved to Gayton.At the time of the 1851 census Walter Hall waslisted as being a farmer employing 3 men, and hiswife a miller employing 4 men. Ten years later in1861, Walter Hall was running the Mill at Gayton,and Andrew Ainslie Common was employed thereas a Miller. He was then 19 years old.It is not known when Andrew Common beganworking in Gayton, as a Miller, but it is likely tohave been sometime after Walter Hall took overrunning the Mill from Robert Matthews, which wasin 1853.It was whilst working at Gayton Mill that AndrewAinslie Common learned the meaning of hardwork, dedication and perseverance that were to


Gayton Mill in 1910 and in 2003.

most comfortable and where he gained a numberof lifelong friendships. This is evident by thewarmth and affection leading astronomers like theSir Frank Dyson, Henry Hall Turner and others hadfor him.EalingIn about 1876, Andrew Common moved from hishouse near Regents Park, to No. 63 Eaton Rise,Ealing, where he remained for the rest of his life.His occupation at this time was given as ElectricalEngineer and Lead Manufacturer. The later cen-

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journal for 1903 written by Mr. Herbert Hall Turner.‘He was a strong man in all senses, and likedtrying himself to the limit. He turned at the meetingthe British Association in Bradford with his arm in asling, because he had been trying whether couldhold a bicycle out at arms length and hadconsequently ruptured a muscle.’It was whilst he was working for his uncle thatAndrew Common met Ann Matthews, the daughterof Abraham Matthews, a farmer and his wifeMartha (nee Mason). They married on 18th July1867 at St. Nicholas Church, Kings Lynn.It is known that by the time of their marriageAndrew had left Gayton a few years earlier to workfor his other Uncle, Matthew Hall in his buildingmaterial business in Marylebone, Middlesex.His uncle Walter Hall continued to work the GaytonMill until 1872, but died shortly afterwards in 1875.Matthew Hall & CompanyMatthew Hall was a born entrepreneur. He hadstarted his first business in Newcastle in the1830s, where he earned a living as a builder, acabinet maker and Joiner. Sometime before 1848he moved to London, where he set up hisplumbing business in that year. The London PostOffice Directory for 1848 shows him listed as aPlumber at No. 11 Bulstrode Mews, MaryleboneLane, Middlesex, London.Andrew Common began working for him around1865, and by the time of the 1871 we find him withhis wife Ann and their one year old daughter VioletMary, living at No. 17 South Bank, near RegentsPark in London. On the Census Return he listedhis occupation as an Engineer.In the coming years Matthew Hall grew to rely onhis nephew more and more as his businessexpanded to become a well respected and highlyprofitable enterprise. On the death of Matthew Hallin 1878, the running of the business was left toAndrew Ainslie Common. As a result he had themoney and the freedom to take up his passion forAstronomy once again.In 1874 he acquired his very first telescope, a 5½”, Equatorially Mounted Refractor. It was with thisinstrument that he made his first attempts atphotographing the heavens.

Two years later on the 9th June 1876 he waselected a Fellow of the Royal AstronomicalSociety. His passion for Astronomy had notdiminished and he was beginning to be recognisedas someone who would make importantcontributions in the field. The other Fellows of theRoyal Astronomical Society warmed to him notonly for his ability but also for his larger than lifepersonality. It was in their company that he felt


Uncle of Andrew Common, Founder in 1848 Matthew Hall Engineering.

South Bank, Regents Park, St. Johns Wood, 1868.

Eaton Rise, Ealing, c1910.

tive to the red rays - the different effects of thecolours of the planets might be made apparent.Perfection of image would not be of so muchimportance as the effect in producing chemical ac-

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suses of 1891 and 1901 show the transitionbetween Andrew Common’s association withMatthew Hall & Co., and his passion forAstronomy. The 1891 Census gives his occupationas Building Contractor and Astronomer; whilst 10years later his sole occupation has become that ofa Telescope Maker and Employer of Workers.Sometime around 1890 Andrew Common hadgiven up working for Matthew Hall to concentrateall his efforts towards the construction oftelescopes. It is likely that Andrew Common’s sonThomas took over the control of his great uncle’scompany. Both the 1901 and 1911 Censusesstates that his occupation was that of a SanitaryEngineer with the status of Employer. ThomasAndrew Common died in 1912, the year after thedeath of his mother Ann Common (nee Hall).TelescopesIn 1877 Andrew Common decided to upgrade hisequipment - a characteristic exhibited by almostevery amateur astronomer. He purchased two 17inch Glass Discs with the intention of grinding hisown mirror and using them in a ReflectingTelescope of his own design. This idea was soonabandoned; instead he purchased an 18 inchReflector from Mr. George Calver and attached itto a mount designed and constructed by him.He put his new instrument to good use and by thefollowing year, he had communicated to the RoyalAstronomical Society the results of hisobservations of the outer satellite of Mars (Deimos)and the satellites of Saturn; in a paper published inthe Monthly Notices for January 1878. However itsoon became apparent that Andrew Commonwanted to use his new telescope forastrophotography.In the April 1879 edition of the Monthly Notices ofthe Royal Astronomical Society, he published twopapers related to Astrophotography.The first entitled ‘On the desirability ofphotographing Mars and Saturn at the nextconjunction’. In this paper which he presented tothe society the following extract is of someimportance:‘In the December 1878 Number of the Notices ofthis Society the particulars of the conjunction ofSaturn and Mars on June 30, 1879, are given bythe Astronomer Royal.I trust that those astronomers who can will takeadvantage of this excellent opportunity of testingthe relative actinic intensity of light of the twoplanets.As they can then be taken under the sameconditions, and if differently prepared plates areused - that is the ordinary wet plate and iodisedcollodion, and those dry plates that are more sensi-


Such, a construction of mounting as togive the greatest mount of steadiness withthe least amount of Motion;

An effectual means of re-silvering themirrors and of protecting them from dew;

A safe, steady, and easily adjustedplatform for observer, allowing about twohours' continuous observation without thenecessity of any motion, except that fromthe observer’s place, and of ready access;

A suitable locality for the erection of thetelescope.”

The suggestions made by Andrew Common in thispaper are of fundamental importance and areinstrumental to achieving success inAstrophotography. He was the first person tostress the need for a steady mount fitted with anaccurate motor drive; and the need for wellbalanced and collimated optics free from flexure.Without these criteria being met the chances ofobtaining well focussed photographs of anyastronomical object are at best minimal.Andrew Common heeded his own advice and byJuly of 1879 he had obtained a new 37 inch mirrorfrom George Calver, which he then mountedaccording to the principles he had outlined in hispaper. The mounting he designed was a radicaldeparture from the norm. It showed greatengineering skill, and paid particular attention forthe need to reduce friction between the movingparts. For example his design required the polaraxis to be partly floated in mercury in order toreduce friction between adjacent surfaces. He alsoplanned (but did not implement) for the use of anelectric clock to accurately follow the movement ofthe stars caused by the diurnal motion of the Earth.With the 3-foot reflector Common made visualobservations of the satellites of Mars and Saturn,and the nebulosity embedded in brightest stars ofthe Pleiades.In the ‘Observatory’ Journal of 1880, AndrewCommon published further photographs of Jupiternow taken with his new 3 foot reflector on the 9thSeptember 1879. The Editor noted the following:“We are Indebted to Mr. Common for the enlargedprints from photographs of Jupiter (Plate III.), takenwith his magnificent 3-feet silver-on-glass reflector.Small though these photographs are, they give usmuch valuable information; and they have thisgreat merit, as compared with the drawings ofmost observers, that they can be relied upon asaccurate. It is little to the credit of those whoattempt to make astronomical drawings, that aphotograph less than 1/20th of an inch in diametershould be sufficient to expose the inaccuracies ofdrawings on 300 or 40 0 times the scale. In this

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tion on the plate.To show the possibility of doing this, I beg to laybefore the Society two photographic plates, onewith a row of pictures of Jupiter (showing the effectof a slight difference in the exposure on the imageboth as to size and density), and the other apicture of Saturn, all taken with an exposure ofabout 2 ½ seconds in the case of Saturn, and stillless in the case of Jupiter, by an eighteen-inchsilver-on-glass Newtonian telescope.March 1879It therefore seems that by before March 1879Andrew Common had used his 18 inch Reflector toobtain photographs of Jupiter and Saturn using DryGelatin Plates, and not the Wet Collodion plates(developed by Frederick Scott Archer). Thephotographs he obtained were too small to showany detail on the planet’s surface.His second paper of April 1879 dealt with a subjectfor which Andrew Common true claim to fame as a‘Great Astrophotographer’ lies - ‘Note on LargeTelescopes with suggestions for mountingReflectors’.In this paper he considers the mounting ofReflectors and how best such a mounting shouldbe constructed.“Having, then, by this process of selection got thesilver-on-glass reflector on the Newtonianprinciple, it becomes necessary to consider themounting; and here we come to what may beregarded as the vital point; for on the propermounting of the reflector, so as to point it to anyobject in the heavens, and follow that object in itsdiurnal motion, while retaining all the conditionsthat are favourable to the best performance of theoptical part, a great deal depends. As far as Iknow, no endeavour has been made to really findout these favourable conditions and make themounting suit them, except in a partial manner.I have endeavoured to find them out, and proposeto indicate how they ought to be attained. They areas follows: No tube properly so called; No mass of metal either below or at the

side of the line joining the large and smallmirrors;

An equatorial mounting capable ofdirection to any part of the visible heavens,and of continued observation past themeridian without reversal;

An efficient means of supporting the mirrorwithout flexure;

Driving clock. Circles to find or identify anobject and conditions taken to eye end;

A collimator for the ready adjustment ofthe mirrors;


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Great Orion Nebula’ M42 Photographed by Andrew Common 1883.


36 inch Reflector at Ealing.

now erected. It is intended to replace thisinstrument with one of 5-foot aperture, madeexpressly for photography, with a mounting havingfor the polar axis a hollow iron cylinder floating inwater, so as to reduce the friction and vibration ofa merely mechanical mounting.The disk of glass for the large mirror was obtainedin 1883, and seems to be all that can be wishedfor.”It is apparent that shortly after he had successfullyimaged the ‘Great Orion Nebula’ in the March of1882, he had been thinking about building an evenlarger reflecting telescope, and by the followingyear the plans for its construction were in placeand the glass blank for his ‘monster’ 60 inchreflector had been purchased.

The construction of the 60 inch Reflector was to bethe great work of his life into which he would putmonths and years of patient effort, hard work andgreat skill into its completion. The annual reports ofRoyal Astronomical Society on the work carried outby the observatories of its members providevaluable insight into the progress made by AndrewCommon on the construction his 60 inch Reflector.

Andrew Common wrote in his report on the EalingObservatory for 1885:

“Experiments in stellar and astronomicalphotography with various kinds of telescopes havebeen made. The De La Rue polishing machine hasbeen removed from the University Observatory,Oxford, and erected in the workshop, and atemporary mounting and house is in the course oferection for further experiments.A comet was found on the night of Friday, the 4thof September, and change of position noticed thatevening. This proved to be a comet already founda few days before by Brooks in America. A seriesof observations were made on the Nova inAndromeda immediately after the announcementfrom Dun Echt.”

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connexion we would invite our readers to compareCapt. Noble's representation of Jupiter in the 'Monthly Notices' for January with Mr. Common'sphotograph of Jupiter and the Red Spot. Thephotograph of Jupiter and his four satellites isimportant, as showing the relative brightness of thesatellites”He also obtained a photograph of a Comet on the24th of June 1881, on the same night that it wasphotographed by Henry Draper in America. It wasone of the earliest successful photographs of acomet.Andrew Common's energies with his newtelescope were however mainly devoted to theimaging of the ‘Great Orion Nebula’ (M42). His firstattempt was on the 20th of January 1880, and wasa total failure, but he patiently improved the drivingof his clock and took advantage of each increaseof sensitiveness in photographic plates till on the17th of March 1882 he obtained a photograph"which excited the admiration of all theastronomers who had an opportunity of inspectingit’.He still further perfected the guiding of histelescope, and obtained on the 30th of January1883, with an exposure of 37 minutes, the splendidphotograph with which all astronomers are familiar.Of the merits of this photograph he modestlyremarked:"Although some of the finer details are lost in theenlargement sufficient remains to show that we areapproaching a time when photography will give usthe means of recording, in its own inimitable way,the shape of a nebula and the relative brightnessof the different parts in a better manner than themost careful hand-drawings."He later on the 28th February 1883 obtained aphotograph of M42 with a longer exposure of 60minutes.In 1884 Andrew Common was awarded the GoldMedal of the Royal Astronomical Society for hiswork on Astrophotography and in particular hisphotographs of the Great Orion Nebula.Shortly after he received the Gold Medal he soldhis 3 foot reflector to Mr. Edward Crossley, aHalifax businessman and passionate amateurastronomer.In the annual report of his Observatory at Ealingfor the year 1884, Andrew Common remarks:“During the past year a small number of celestialphotographs have been taken, including two of theDumb-bell nebula, and a number of experimentshave been made in stellar photography.The 3-foot Reflector has passed into the hands ofMr. Crossley, of Halifax, at whose Observatory it is


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36 inch ‘Crossley’ Reflector, Lick Observatory, Mount Hamilton, California.


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Schematic Drawing of the 5 foot Reflector.


“The 5-foot reflector was practically completed lastSeptember, and is now ready for work. On the fewoccasions that the weather has permitted, sometrial photographs have been obtained that show avery satisfactory advance on those taken in 1883with the 3-foot. It is intended to devote thistelescope to the direct photography of the moreimportant nebulae and to spectroscopic work onsuch objects as can be best observed with such anaperture.The 6-inch achromatic is in good order. The transitinstrument has been dismounted, and the room inwhich it stood used for a battery-room for twobatteries of E.P.S. cells, available for lighting orpower in the Observatory.In the making of the 5-foot mirror much work wasdone of an experimental character in order toacquire the art of working glass. Many kinds ofgrinding and polishing substances, both for toolsand for grinding or polishing the surfaces weretried, as well as different lubricants and methods oftesting. From the experience thus gained a definiteplan of working and testing curved surfaces hasbeen arrived at that is very certain, a mirror of 30inches diameter having been since figured in acomparatively short time.In addition to the machine made for the 5-foot’smirror, on which mirrors of smaller size can befigured, another machine has been erected forgrinding and polishing mirrors under 30 inches,both curved and plane, with means for figuringmirrors of very short focus. It is intended to preparesome mirrors of about 20 inches diameter, with aview of finding the shortest focus that will work; assuch mirrors might be of great use on nebulae,comets, and the corona during eclipse.”However by the time of the next report for 1889,progress had been halted and if anything had gonebackwards, as Andrew Common explains:“The 5-foot mirror not being found on trial to bequite satisfactory, owing to the slight ellipticity ofthe image of a star, probably duo to the fact thatthe disc of glass had been resting in a slopingposition for some years, was taken out in thespring and refigured and re-silvered; the imagenow given is very much better; owing to the verybad weather very little work has however beendone with it yet.The 20-inch mirrors mentioned in the last, reporthave been made, and two of them sent out to theEclipse of December 22. As far as trials madebefore they were sent enable one to judge, suchshort-focus mirrors are likely to be very efficient.One is now being erected for regular use in thehouse lately covering the 6-inch achromatic whichhas been dismounted.

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So during 1885 there was no apparent progressmade on the construction of the 5 foot reflectorapart from setting up the mirror polishing machine.The report for the year 1886 is more positive andindicates that considerable progress had beenmade:“The last year has been entirely devoted to theconstruction of the 5-foot reflector. The machinefor grinding was completed in September, andgreat progress has been made with the mirror.Photography has been used to obtain permanentrecords of the state of the surface by using thereflected light from a pinhole (illuminated by alamp), as in the system of testing used byFoucault. It is found that so small a quantity of lightas can come through a hole .004 inch placed atthe centre of curvature can be photographed in afew seconds after reflection from the surface.A series of photographs have been taken from thefirst rough polish to the present state, and will becontinued.The kind of mounting has been determined upon,and the heavy work put in hand. It is hoped thatthe whole may now be completed without furtherdelay.The telescope is to be devoted to photography,and the mounting has been designed to give thegreatest amount of steadiness and perfection ofmovement.”The following year’s report for 1887 indicates thatthe construction of the telescope is nearingcompletion:“Considerable progress has been made in theconstruction of the 5-ft. reflector. The mirror hasbeen polished and figured several times in order togain experience in the art. There is evidence ofinternal strain in the glass, which may or may notaffect the image, and it is contemplated to orderanother disc in case this one does not permit of agood final figure.The mounting is in a forward state, the telescopetube being connected to the polar axis, this latterbeing a wrought-ironcylinder about eight feet diameter which will float ina tank of water, so as to relieve the friction in themanner mentioned in vol. xliv. of the MonthlyNotices, p. 367.The house or covering for the telescope, which willalso carry the platform for the observer when thetelescope is used as a Newtonian, is framedtogether and partly erected. It is hoped that thewhole will be ready to use in the autumn.”The telescope was finally completed in theSeptember of 1887, as stated in the report for1888:


special apparatus for watching the slit during thelong exposures necessary for photographing thespectra of nebulae.Up to the present time, owing to bad weather, onlypreliminary work on the Orion nebula has beenpossible with the spectroscope. The spectrum ofthis nebula has been observed on three occasions(the only three possible since November), but nonew lines have been detected.As mentioned in the last report, the figure of the 5-foot mirror is not perfectly satisfactory owing to aslight ellipticity of the star images seen under highmagnification, this ellipticity being probably due tothe fact that the disc of glass rested in a slopingposition for some years. The new 5-foot disc hasbeen obtained from France, and the grinding ofthis will be proceeded with at once. Both thegrinding machines have been kept in constantwork.A 36-inch mirror of 11 feet 3 inches focal lengthhas been made for the Science and ArtDepartment, South Kensington, and two 30-inchmirrors of the same focal length have also beenfinished, one of these being made with a sphericalinstead of a parabolic curve to be used in thetesting of flat mirror surfaces. Another 30-inchparabolic mirror is now in hand and nearly finished.Two 20-inch mirrors of 45 inches focal length havealso been finished during the year, and have beenthoroughly tested in the 20-inch telescope erectedin place of the 6-inch refractor.A series of photographs of the Pleiades, theDumb-bell nebula, of various clusters, and severalphotographs of the Andromeda nebula were takenwith this telescope during the testing of the 20-inchmirrors, but the photographs have not yet beencompared and measured. An instrument for rapidlycomparing and measuring photographs, asdescribed in the "Observatory," in August 1890, isalmost completed, and will be used for a fullexamination of these photographs as well as forthose taken with the 5-foot reflector.A long series of experiments on the photographicdetermination of the reflecting power of silver,speculum metal, and silvered-glass surfaces(prepared by different silvering processes), and onthe reflecting and transmitting power of plain glasshave been carried on, but are not yet completed.The results will be communicated to the Society assoon as the experiments are concluded. A numberof trials have also been made of various silveringprocesses, and a new process has been adoptedby means of which a perfect film of any requiredthickness can be formed with absolute certainty,and mirrors of any size can be silvered with easeand rapidity.

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A new disc for the 5-foot telescope has beenordered and is expected shortly, as well as severaldiscs of large size for plane mirrors. In view of themuch better results that may be hoped for from theuse of such piano mirrors as siderostats,particularly in eclipse and spectroscopic work infuture, the making of plane mirrors of very largesize is next to be taken up.”After over four years of labour the 60 inchtelescope was still not completed and a new mirrorhad to be ground.Finally during 1890 Andrew Common was able touse it for its intended purpose, although the newmirror had not been ground and the inclementEnglish weather was as is usual a key factor indampening any adventure requiring itscooperation:“The weather during the past year has been veryunfavourable for observation at Ealing. Advantagehas been taken of every available night, but the 5-foot telescope has only been in use 48 nights sinceMarch 1890, and only 24 of these were suitable fornebula photography. In all 31 photographs ofnebulae and clusters have been obtained.The principal nebula photographs are Orion 6 (onewith 2 hours 35 minutes exposure, and one with 2hours' exposure on plates stained with erythrosin;the first mentioned is much the best hithertoobtained); the Dumb-bell nebula 5 (the best with110 minutes exposure on July 24, showing a largeamount of detail) ; M 77, 3 (one with 150 minutesexposure, showing the spiral structure veryclearly); M 99, 2 (with exposures of 2 hours and 2¼ hours, with spiral structure clearly shown) ; M96, 1 hour; M 88, 1 hour; M 59 and 60, 2 hours 5minutes; Gen. Cat. 4045,2 hours; Gen. Cat. 2203,2207, 2211, 1 hour; and the Pleiades, 1 hour;showing nebulae. Amongst the clustersphotographed may be mentioned those of M 2(four photographs) and of M 5 (four photographs),the latter showing some new variable stars nearthe cluster; see Monthly Notices, vol. 1., page 519,June 1890. Photographs of the Moon have beenobtained on nine nights during the year, andUranus and its satellites have been photographedon two occasions.Observations have been made of the satellites andgeneral appearances of Saturn, Uranus, andNeptune whenever possible, the observations ofMimas being communicated to the Society in May1890, and published in the Monthly Notices, vol. 1.Page 404.A double wire micrometer, with position-circle andelectric light illumination, has been made for the 5-foot telescope, and also a star spectroscope(which was supplied at the end of 1890) fitted with


mirrors for other people and for other projects. Notonly that, but he gave generously of his time,expertise and money. If someone wanted a mirrormade, Andrew Common obliged. For example hemade two 20 inch mirrors for the Solar Eclipse of1889, which he presented to the Royal Society;two 16 inch mirrors for the eclipse expedition of1896 followed; as did a 30 inch mirror for the SolarPhysics Observatory and in 1900 a 20 inch mirrorfor the National Physical Laboratory. Theadditional effort required to complete these ‘extraprojects’ must have had a delaying affect oncompletion of his 60 inch telescope.Thirdly, the concerns Andrew Common had for thesighting of his 5 foot reflector amid the everincreasing glow of nearby London must haveweighed heavily on his mind, as must the poorweather England always faced!After his death the telescope was sold to HarvardCollege Observatory and later sent toBloemfontein in South Africa.However, the final reason for abandoning the 5foot reflector was that Andrew Common foundsomething to do which he considered moreimportant.Andrew Common became interested in developingtelescopic gun sights for use by the Army and theRoyal Navy. His knowledge of optics together withhis great practical skills made him the ideal personto successfully see such a project to fruition. It isnot known how he became involved in such aproject, but it was in his nature to do something forthe common good and not just for himself.As regards its national importance the followingwords of Captain Percy Scott, R.N., spoken at adinner at the Savage Club on 22nd of November1902, will suffice:"The nation owed a deep debt of gratitude to Dr.Common for the great improvements that he hadmade in gun-sights. It mattered not how good thegun was, nor how good a man there was behind it;unless the sight was perfect good firing could notbe made. The great stride by the British Navylately in that direction was entirely due to Dr.Common. ... He had produced a telescope gun-sight which would, when properly used, quadruplethe fighting efficiency of our battleships”.Andrew Ainslie Common died suddenly of a heartattack in his study at No. 63 Eaton Rise, Ealing onthe 2nd June 1903; he was nearly 62 years old. Hewas survived by his widow Ann (1840-1911) andtheir four children - Thomas Andrew Common(1875-1912), Violet Mary Common (1869-1952),Lillian Martha Common and Ida Common (1880-1951).He will be remembered not only for his magnificentBB

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The scarcity of good nights, partly due to thenearness to London, limits the use of the largetelescope very much, and it is in contemplation toremove it to some more suitable position.”The above account given by Andrew Commonclearly shows that his new telescope wasbeginning to become useful, and had been used totake photographs of a number of the more wellknown Deep Space Objects; exactly the sort oftargets the modern imager would choose - the‘Dumbbell’ Planetary Nebula M27 in Lyra; theSeyfert Galaxy M77 in Cetus; the ‘Pleiades’Cluster M45 with its embedded nebulosity; and theGlobular Clusters M2 in Aquarius and M5 inSerpens Caput. He was however becomingconcerned about the suitability of the telescopeslocation near to the London metropolis - he hadtaken note of the advice given in item No. 10 of hispaper of April 1879.The year 1890 was the best the telescope was to‘see’ during Andrew Common’s lifetime, for thereport given to the Royal Society in 1891 was instark contrast to the one given the previous year:“During the past year a new 5-foot mirror has beenmade for the telescope. This piece of glass hasproved to be almost if not quite - perfect, and themirror is a most excellent one.Some very fine photographs of nebulae and theMoon have been taken, that will be laid before theSociety.A new grating spectroscope has been fitted to the5-foot. Work on plane mirrors has been carried onin the workshop.”That was all he said and the telescope was neverused again, why? There a number of factors whythis proved to be the case.Firstly, it is known that Andrew Common narrowlyescaped a fall from a high platform when he wasusing the telescope as a Newtonian Reflector. Thismust have shocked him as such a fall could easilyhave proved fatal. He made some attempts toconvert the telescope to a Cassegrain system, butthe prospect of drilling a hole through the centre ofthe mirror he had spent so much time on - seemednot to be a good idea. An attempt was made toavoid this catastrophe in the waiting by devising asystem where the secondary mirror was inclinedso that the image was clear of the primary mirror.Despite some initial success the method provedunsatisfactory and Andrew Common abandonedthe idea altogether and the telescope he had livedwith for so long.Secondly, the reports he prepared during the yearsthe 60 inch reflector was undergoing construction,showed that it was not the only project with whichAndrew Common was involved in. He was making


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Andrew Common’s 60 inch Reflector, at Harvard College Observatory, c1910.


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60 inch Reflector, Boyden Observatory, Bloemfontein, South Africa.


later, when George Ellery Hale began to plan forthe establishment of a large observatory on MountWilson in California, the use of a large refractingtelescope was not even considered. The Crossleyhad shown the way to the future of astronomy.Large reflecting telescopes would now dominate20th-century astronomy. The Crossley 36-inchreflector is found a few hundred yards southwest ofthe Main Observatory Building of the LickObservatory and is still in use as an operationalscientific instrument for the study of the stars andgalaxies. The Crossley 36-inch reflectingtelescope, at the Lick Observatory, marked the firstmodern application of a reflecting telescope toastronomical studies.60 inch ReflectorShortly after his death Andrew Common’s 60 inchReflector was purchased in 1904 for the HarvardUniversity Observatory, by its Director EdwardCharles Pickering. He intended to continue using itfor the Harvard photometry survey down to as faintstars as possible with the instrument. It was foundthat the definition was far from satisfactory, and infact very little use was indeed made of it as aroundthat time there occurred the rapid development ofphotographic stellar photometry, making visualtechniques less attractive. However, HarlowShapley who became Director at the HarvardCollege Observatory in 1921 required access to alarge telescope to further his researches on thelimits of the visible universe. The telescope wasrefurbished and sent to the Harvard’s BoydenStation in Bloemfontein, South Africa. It becamefully operational in 1933. The funds for therenovation had been obtained from the Rockefellerfamily, and the telescope was renamed the‘Rockefeller Telescope’. The ‘RockefellerTelescope’ had an inauspicious start to life, butfollowing its move to the Boyden Observatory itbegan to become useful, befitting a telescope witha 60” mirror. It is still in use today and activelyparticipates in collaborative research projects withother astronomical institutions.

Stefan Hughes can be reached via email:[email protected]

Visit his home page with great stuff to history ofastrophotography http://www.artdeciel.com/Exposure/

and his blog for astrophotographers: http://www.artdeciel.com/

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images of the ‘Great Orion Nebula’, but moreimportantly for the guidelines he laid down forachieving successful astronomical images and ofcourse the two great reflectors he had spent somany years of hard effort in their construction.It is fitting and entirely appropriate that these twotelescopes are not only still in use but are inAndrew Common’s own words situated in ‘asuitable locality for the erection of the telescope’amid clear dark skies - now far away from thecloudy nights in Ealing where they first saw theoccasional light of the stars - which so lit up the lifeof their creator.

Notes on Andrew Common's Two GreatReflectingTelescopes

36 inch ReflectorIn 1884 Common sold his 36-inch reflectingtelescope to Edward Crossley of Halifax,Yorkshire, England. The weather in Halifax provedtotally unsuitable for a telescope of this size andlittle use was made of it. As a result EdwardCrossley donated the telescope to the LickObservatory shortly after his retirement fromastronomy in 1893. The Crossley 36-inch reflectorat the Lick Observatory was the first of a long lineof metal-film-on-glass modern reflecting telescopesthat have dominated major astronomical advancesfor the past century. In addition, the Crossley hasproduced more scientific results than any othertelescope of its size, including several historicallyimportant studies in stellar evolution, the structureand spectra of planetary nebulae, and thediscovery and spectral analysis of faint variablestars in young clusters. The Crossley alsocontributed to studies that confirmed the expansionof the universe. Within a short time the Crossleyreflector was put to good use when James E.Keeler initiated a program of nebular photographywith it. Keeler's photographs showed the existenceof hundreds of spiral nebulae that are now knownas galaxies. Neither Keeler nor anyone else at thetime realized that nebulae were predominantlyextragalactic, but Keeler, using Crossleyphotographs, was the first to realize that theseobjects were a major constituent of the universe.After Keeler's death, astronomer Charles DillonPerrine completed Keeler's observational program,and in 1908 published a remarkable selection ofCrossley photographs in memory of Keeler.Keeler's and Perrine's success with the Crossleyreflector was probably more influential than anyother single factor in convincing professionalastronomers of the practical effectiveness of largereflectors. By the early 1900s, as a result ofKeeler's and Perrine's work with the Crossley, itwas apparent that the future of large telescopeslay with mirrors rather than lenses. A few years


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2.75” English Brass RefractingTelescope, Late 18th Century

Descriptions: A superb English brass refracting telescope with original tripod stand. Measurements: height - 51 cm, width/length - 98cm, diameter - 7 cm. Credit: R. Jorgensen Antiques


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Credit: R. Jorgensen Antiques


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3” EnglishTableReflectingTelescope,18th Century

Descriptions: A fine reflecting late 18th century (1785) shagreen covered telescope in the manner of Adams, in working order.Measurements: height - 36 cm, width/length - 46, diameter - 8 cm. Credit: Hansord Antiques


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Credit: Hansord Antiques


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In May 2012 was published Charles Rydel's book "Design and construction of telescopesand astrographs for amateurs" with a preface by J. C. Pecker, astronomer, member of theAcademy of Science and Honorary Professor at the College de France. You will find his

book in bookstores (for example Amazon).

In about 500 pages, this book brings together the work of well-known amateurs. Theydeliver all the secrets of their achievements. This book is structured into five main

chapters:

1) Optical Design with the software OSLO.2) Construction and use of machinery to cut and polish the mirrors.

3) Testing an telescope objective (interferometry, self Foucault)4) Travel telescopes and large amateur telescopes

5) Amateur instruments to study the sun.


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NNooww AAvvaaiillaabbllee!!

Shop: http://www.catchersofthelight.com/shop/Affilate: http://www.catchersofthelight.com/shop/affiliates.aspxFlip Book: http://www.catchersofthelight.com/eBookIntroduction.aspxeBook: http://www.catchersofthelight.com/eBooks/B.0_CatchersoftheLight_Introduction_eBook.pdf


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AAbboouutt tthhee AAuutthhoorrStefan Hughes has been observing the night sky since he was 12 years old, when he got his first telescope asmall 3.5" Reflector, which was in his own words 'pretty useless'. He then got his first serious telescope threeyears later - a 6" (15cm) equatorially mounted Newtonian Reflector, which he used to look mainly at themoon and planets. He was so taken with Astronomy that he decided to make it his career, though ironicallybecoming a theoretical astronomer specializing in the field of Celestial Mechanics, being a student ofDesmond King-Hele and the late Andre Deprit. In 1978 he was awarded a PhD for his thesis on the motionof Artificial Earth Satellites, which was published as a series of papers in the Proceedings of the RoyalSociety. After spells as a Research Fellow and University Lecturer he moved into the world of Computerswhen work became scarce in Astronomy, as a software designer and later project manager. During this timehe drifted out of Astronomy, concentrating on his career and raising a family. He also had a further careerchange and spent five year training to become a Genealogist and Architectural Historian; which he practicedprofessionally for a number of years. In 2001 he moved to the island of Cyprus with his wife, and is nowsemi-retired devoting the majority of his time to his rekindled enthusiasm for Astronomy and in particular toDeep Sky Astrophotography, and of course the 'Art de Ciel' website. He is currently writing two books one onthe history of astrophotography called ‘Catchers of the Light’ and the second a biography with thephotographic historian Dr. Marcel Safier on the Victorian Photographer Frederick Scott Archer entitled ‘Tothe Sons of the Sun’.


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AATTMM LLeetttteerrss JJoouurrnnaallPublishing an article on the ATMLJ iscompletely free. We are keen to receiveoriginal papers, articles and casestudies on any relevant telescopemaking topic. Here is no limitation onthe article pages or number of photos.There are no deadlines. Articles are runin the order received, so the sooner yousubmitted them in the sooner they willappear in print.

The biography provided will be used tocredit the author; with links made toyour website and email address whereprovided. Although we cannot makepayments for articles published, we dodonate you with a free copy of thecurrent issue where your article waspublished.

Submit your article now and make yourexperience public to over 100 ATMLJreader, all advanced amateur astro-nomers and telescope makers.



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In the next Issue of ATM Letters

William Usherwood (1821-1915) The Comet Man

William Usherwood a commercial photo-grapher from Walton-on-the-Hill, Surrey,England, took the first ever photograph of acomet when he captured Donati’s comet fromnearby Walton Heath, Surrey on the 27thSeptember 1858, beating George PhillipsBond from Harvard Observatory by a night!Unfortunately, the photograph taken byUsherwood has been lost...

ATMLJ 10th Anniversary GiftBeautiful Jupiter Satellites Widget

And more …

Documents

Issue Vol. 10, 04 2012