www.neneastro.org.uk July 2015

July MeetingsThursday 2nd July: Sudborough Village Hall, Main Street, Sudborough at 8pm.

Monday 20th July: Chelveston Village Hall at 8pm. Professor David Rothery -‘The Planet Mercury - Newly Revealed’.

The New Horizon Spacecraft Flys Past Pluto on 14th JulyProviding Us Our First Detailed Views Of This Far Flung World.

Forthcoming Events

Thursday 2nd July: Meeting at Sudborough Village Hall, Main Street, Sudborough at 8pm. The monthly night sky guide and aselection of the latest astro-news will be presented, followed by an astronomically themed DVD.

Friday 10th July: ‘Starting Out In Astronomy’. A special introductory evening being hosted as part of ‘Rushden Party Week.Rushden Hall, Hall Park, Rushden at 8pm. Free admission.

Monday 20th July: ‘The Planet Mercury - Newly Revealed’. Professor David Rothery at Chelveston Village Hall, CaldecottRoad, Chelveston at 8pm. £3 admission.

Wednesday 12th August: Perseid Meteor Watch at Chelveston Village Hall, Caldecott Road, Chelveston from 9.30pm.

Monday 17th August: Informal meeting at Chelveston Village Hall, Caldecott Road, Chelveston at 8pm. The monthly skyguide and a selection of the latest astro-news, amongst other items.

Thursday 3rd September: ‘Medieval Astronomy’ by Seb Faulk. Sudborough Village Hall, Main Street, Sudborough at 8pm.

Friday 4th September: Starnight Observing Session at Chelveston Village Hall, Caldecott Road, Chelveston from 8pm.

Note that there is no Sudborough Meeting In August

The Planet Mercury - Newly Revealed

Many questions remain for ESA’s BepiColombo to answer ten years from now, but thanks to NASA’s MESSENGER (orbitingMarch 2011 to March 2015) we now know far more about the closest planet to the Sun than was possible from ground-basedastronomy and the Mariner 10 flybys in the 1970’s.

Mercury is a rocky planet with a disproportionately large iron core. The outer core is molten and dynamo processes theregenerate a magnetic field (unique among the terrestrial planets apart from Earth). It has a rich and dynamic exosphere. Thesurface is perplexingly rich in volatile elements such as S, K, Na and Cl, and there is widespread evidence of explosivevolcanic eruptions (mostly more than three billion years ago, but with some extending into the past billion years) that must bedriven by expanding volatiles. Such its primordial rocky fraction to have been stripped away, possibly in a giant impact.

Thermal contraction of the planet has led to widespread development of ‘lobate scarps’ at the surface that have taken up atleast 7km of radial contraction. The most recent macroscopic process to sculpt the surface (other than ongoing impactcratering) is the formation of ‘hollows’ - occurring as fields of steep sided, flat-bottomed depression tens of metres deep,where a surface layer has been removed, seemingly by some sort of sublimation process. The volatile phase involved hasnot been identified.

Visitors welcome.

Stephen Howard

Right: Dr Ralph Cordey answers members questionsfollowing his talk on the Solar Orbiter Spacecraft at ourSudborough Meeting In June.

Don’t forget that you can follow the Nene ValleyAstronomical Society on Twitter and we also havea Facebook Page.

Contributions for the next Stargazer newsletter arewelcome and can either be handed to Steve Williamsat meetings or e-mailed to astrosteveuk@yahoo.co.uk

Toby Jewell

A lecture by Professor David Rothery

Professor of Planetary Geosciences at The OpenUniversity and currently ‘Lead Co-Investigator’ for

Mercury Imaging X-ray Spectrometer.

Monday 20th July at 8pm

Chelveston Village Hall

Eagle’s EyeDave Eagle looks ahead to the sky sights for July

The Starchart to the left (fromheavens-above.com) shows howthe sky will look on July 1st at11pm and July 15th at 10pm.

High overhead is the head ofDraco, the dragon. The fourstars of the lozenge asterismvery distinctive. Below Draco isHercules with the great globularCluster M13, a beautiful ball ofstars. Don’t forget to look at theother globular cluster M92 aswell. Low in the southern skyOphiuchus the Serpent Beareralso contains globular clusters.Try and hunt out the fast moving9.5 magnitude Barnard’s Star,close to a distinctive V shapepattern of stars. If you have agood horizon towards the north,you may be able to see Capellain Auriga twinkling very lowdown. This winter star will beoverhead in 6 months time. Overin the eastern sky Leo and Virgoare setting fast. Above them isthe bright Arcturus, shining like abeacon towards the west. In theeastern sky, the stars weassociate more with summer arenow coming well into view.Cygnus Aquila and Lyra and theassociated Milky Way. A bonusis the nights are gradually gettinglonger..

The Moon:2nd & 31st July - Full.8th July – Last Quarter.16th July – New.24th July - First Quarter.

Very Thin Crescent Moons:13th & 14th July – Morning Sky.18th July– Evening Sky.

The Moon will be close to:Neptune on the 6th July, Uranus on the9th July, Hyades Star Cluster on 12thJuly, Mercury and Mars on 15th July(very difficult to see), Venus on the 18thJuly, Spica on the 22nd July and Saturnon 25th and 26th July.

Solar System:

MERCURY – Reaches superiorconjunction on the 23rd so is not visible.

VENUS – Moving rapidly towards theSun, very close to Jupiter on the 1stover in the western sky after sunset. Willbe lost from view by the end of themonth as it dives into the Suns glare

MARS – Still too close to the Sunglare, so will not be seen this month.

JUPITER – Also diving westwardstowards the evening twilight, passingvery close to Venus on the 1st. Will belost by the end of the month.

SATURN – Visible low in the southwest at magnitude 0.6 in Libra. Its ringsare now very well displayed towardsthe Earth.

URANUS & NEPTUNE – Both visiblelow in the eastern sky before dawn,now starting to become a little biteasier to spot.

PLUTO – At opposition at magnitude14.3 in Sagittarius. New Horizonspasses Pluto and its moons on the14th. Keep up to date on the mission atNASA’s New Horizons Web site:http://pluto.jhuapl.edu/

METEORS - PERSEIDS - This reliableshower is active between the 23rd ofJuly and the 20th of August. Maximumoccurs next month.

Comet PANSTARRS 2014 Q1 –Reaches Perihelion on the 5th. It ispredicted to be visible as a 3rdmagnitude object in the constellation ofGemini. So will only be visible for ashort time after sunset.

Comet Churyumov–Gerasimenko67P – Should start to be visible in thesame part of the sky, moving throughTaurus and into Gemini next month asit approaches perihelion. It should be apredicted magnitude 12 so it will be achallenge to find and image in theeastern sky before dawn starts tobreak. But go on give it a go. You mightjust be pleasantly surprised.

For a much fuller guide, charts,graphics and the latest news, visit

my web site at:www.eagleseye.me.uk.

Earth's moon probably formed during acataclysmic impact between Earth and aMars-size object that scientists call Theia. Astudy of meteorites suggests that thiscollision may have occurred 4.47 billionyears ago, scientists say.Image Credit: NASA

Meteorites HelpDate The

Formation OfThe Moon

From Space.com

The cataclysmic collision betweenEarth and a Mars-size object thatforged the Moon may have occurredabout 4.47 billion years ago, suggestsa study of meteorites with ancientfragments from that cosmic impact.This finding suggests that, one day, itmay be possible to find samples ofwhat the primordial Earth was likebefore the giant impact that formedthe Moon, or to uncover bits of theimpacting rock itself.

Earth was born about 4.5 billion yearsago, and scientists think the Moonformed shortly afterward. The leadingexplanation for the Moon's origin,known as the giant impact hypothesis,suggests that the Moon resulted fromthe collision of two protoplanets, orembryonic worlds. One of those wasthe young Earth, and the other was apotentially Mars-size object calledTheia. The Moon then coalesced fromthe rubble.

"By understanding the Moon, we cantell the story of the earlybombardment of Earth," study leadauthor William Bottke, a planetaryscientist at the Southwest ResearchInstitute in Boulder, Colorado, toldSpace.com.

However, the precise timeline of thisgiant impact event is under dispute.The ages of the most ancient lunarsamples the Apollo astronautsbrought back are still debated, sincethese samples have typically beenbattered and heated by subsequentcosmic impacts.

"To understand the formation andevolution of our world as well asthose in the inner solar system, weneed to understand the timing ofmajor events during the planet-formation era," Bottke said.

To find out more about this giantimpact, scientists developed acomputer model of the event. Theyfound that the impact not onlycreated a disk of debris near Earththat formed the Moon, but it alsoejected huge amounts of rubble —as much as several percent ofEarth's mass — away from Earthand the Moon.

The simulations found that numerousfragments from the Moon-formingimpact — hundreds of millions ofwhich were at least a mile (1.6kilometers) long — blasted theasteroid belt, striking asteroids thereat speeds of more than 22,370 mph(36,000 km/h), more than twice asfast as typical crashes in the belt.These collisions from the Moon-forming impact would havegenerated superheated material, theresearchers said.

"In an explosion, there is oftencollateral damage, where nearbybuildings and innocent bystandersare affected," Bottke said."Investigators can learn about theexplosive device and the explosionitself by studying what happened topeople, infrastructure, and whethertrace amounts of the explosivedevice can be found among the blastdamage. Here, the 'innocent

bystanders' were the main-beltasteroids."

Collisions against these asteroids inmore recent times returned theseremnants to Earth in stonymeteorites, which the scientists nowhave analyzed and used to date theage of the impact.

The researchers deduced that theMoon-forming impact occurredabout 4.47 billion years ago, inagreement with many previousestimates.

"We can now use asteroids, for thefirst time, to tell us about many ofthe major events that took place inthe inner solar system during theplanet-formation era," Bottke said."This gives us a new window on atime period which has been virtuallyunknown up to now."

This research "raises the intriguingpossibility that trace amounts of theprimordial Earth or Moon formingimpactor called Theia may still befound on asteroids today, orpossibly within some of ourmeteorites," Bottke said. "It may besimply a matter of looking andasking the right questions. Findingthese materials would be one of theHoly Grails of geology — we haveno rocks older than 4 billion yearsold on Earth, and no one knows theexact nature of the original buildingblocks of our planet."

Summer Meteor Showers

The coming weeks are going to be busy times forthose who enjoy watching the skies for meteors,the highlight of which is the Perseid meteorshower which reaches it’s annual peak on August12th. Indeed so popular is meteor watching thatthe general public take an interest and eventhose amateur astronomers who spend their timestudying distant galaxies, have been known tohave an evening or two watching the skies formeteors!

Meteor observing at it’s simplest just requiresyour eyes and a comfortable (reclining) chair. Ofcourse you can make it a bit more fun byobserving within a group or even a little moreseriously by counting and recording some detailson the meteors that you see.

At this time of the year, the night’s are alsorelatively warm and by the end of July, properlyastronomically dark skies are also returningmaking stargazing an even more attractiveproposition!

For meteor observing as with most stargazing,give your eyes around twenty minutes or so tobecome dark adapted. If you intend makingnotes, use a torch with a dim red light and not abright white one. When you feel that you areready, make a note of the time. The simplestmeteor watch involves just counting the numberof meteors that you see over a period of usuallyat least an hour. During a meteor watch when ameteor shower is active you will likely see bothmeteors from the active shower and sporadic(non - shower) meteors. To decide whether ameteor is for example a Perseid, trace the path ofthe meteor backwards. If it goes back to theconstellation of Perseus it is a bona-fide Perseidmeteor. If it doesn’t then it is either a sporadic ora meteor from another shower that is active atthe same time.

If you want to record details on the meteors thatyou see, then groups such as the BritishAstronomical Association and the Society forPopular Astronomy, have observing report formswhich can be downloaded from their respectivewebsites. Information to be recorded includesthe time a meteor is seen, it’s magnitude,whether it is a shower meteor or sporadic andhow easily it was seen.

Although meteors can appear at any point in thesky, when looking for them you want to giveyourself as much sky coverage as possible tomaximise your chances of seeing them. Thereforeit is advised to centre your field of view around 50degrees in elevation.

If you have a DSLR camera and a tripod, then youcan have a go at capturing an image of a meteor.This is however something, speaking fromexperience, which requires an enormous amount ofpatience! Set the camera ISO to a high setting,open the lens to a wide setting and aim for anexposure time of 30 to 60 seconds. Most DSLRcameras can continue to take imagesautomatically, until either the battery runs out or thememory card fills up. Don’t forget to keep an eyeout for the camera lens dewing up!

Meteor Showers In July & August

Delta Aquarids active from July 15 th to August20th. Reach maximum on July 29th. ZHR 15

Alpha Capricornids active from from July 15th toAugust 15th. Reach maximum on August 1st.ZHR 5

Perseids active from July 17th to August 24th.Reach maximum on August 12th/13th. ZHR 80

Kappa Cygnids active from August 3rd to August25th. Reach maximum on August 18th. ZHR 3

Alpha Aurigids active from August 25th toSeptember 12th. Reach maximum on August 31st.ZHR 6

ZHR refers to the Zenithal Hourly Rate, the numberof meteors you would expect to see per hour, underideal observing conditions with the meteor showerradiant at the zenith. In reality therefore, the actualnumber of meteors actually seen by any oneobserver per hour will be lower than the abovenumbers.

If you manage to see any meteors or aresuccessful in capturing any images, then be sure tolet us know and we can include your observationsin a future edition of this newsletter.

Steve Williams