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Space News Update — May 1, 2018 —

Contents

In the News

Story 1:

NASA Sets Sights on May 5 Launch of InSight Mars Mission

Story 2:

Old Data, New Tricks: Fresh Results from NASA’s Galileo Spacecraft 20 Years On

Story 3:

Twin Spacecraft to Weigh in on Earth's Changing Water

Departments

The Night Sky

ISS Sighting Opportunities

NASA-TV Highlights

Space Calendar

Food for Thought

Space Image of the Week

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1. NASA Sets Sights on May 5 Launch of InSight Mars Mission

Illustration of NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight)

Credit: NASA

NASA’s next mission to Mars, Interior Exploration using Seismic Investigations, Geodesy and Heat Transport

(InSight), is scheduled to launch Saturday, May 5, on a first-ever mission to study the heart of Mars. Coverage

of prelaunch and launch activities begins Thursday, May 3, on NASA Television and the agency’s website.

InSight, the first planetary mission to take off from the West Coast, is targeted to launch at 7:05 a.m. EDT

(4:05 a.m. PDT) from Space Launch Complex-3 at Vandenberg Air Force Base in California aboard a United

Launch Alliance (ULA) Atlas V rocket.

Launching on the same rocket is a separate NASA technology experiment known as Mars Cube One (MarCO).

MarCO consists of two mini-spacecraft and will be the first test of CubeSat technology in deep space. They are

designed to test new communications and navigation capabilities for future missions and may aid InSight

communications.

InSight’s Landing Site: Elysium Planitia

Elysium Planitia, a flat-smooth plain just north of the equator makes for the perfect location from which to

study the deep Martian interior.

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InSight, is designed to study the deep interior of Mars. The mission seeks the fingerprints of the processes

that formed the rocky planets of the solar system.

Its landing site, Elysium Planitia, was picked from 22 candidates, and is centered at about 4.5 degrees north

latitude and 135.9 degrees east longitude; about 373 miles (600 kilometers) from Curiosity’s landing site, Gale

Crater. The locations of other Mars landers and rovers are labeled.

InSight's landing on Mars is planned for Nov. 26, 2018, around noon PST (3 p.m. EST / 20:00 UTC).

InSight's scientific success and safe landing depends on landing in a relatively flat area, with an elevation low

enough to have sufficient atmosphere above the site for a safe landing. It also depends on landing in an area

where rocks are few in number. Elysium Planitia has just the right surface for the instruments to be able to

probe the deep interior, and its proximity to the equator ensures that the solar-powered lander is exposed to

plenty of sunlight.

Source: NASA Return to Contents

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2. Old Data, New Tricks: Fresh Results from NASA’s Galileo

Spacecraft 20 Years On -- Ganymede: A Moon Like No Other

This infographic describes Ganymede's magnetosphere. Credits: NASA's Goddard Space Flight Center/Mary Pat Hrybyk-

Keith

Far across the solar system, from where Earth appears merely as a pale blue dot, NASA’s Galileo spacecraft spent

eight years orbiting Jupiter. During that time, the hearty spacecraft — slightly larger than a full-grown giraffe —

sent back spates of discoveries on the gas giant’s moons, including the observation of a magnetic environment

around Ganymede that was distinct from Jupiter’s own magnetic field. The mission ended in 2003, but newly

resurrected data from Galileo’s first flyby of Ganymede is yielding new insights about the moon’s environment —

which is unlike any other in the solar system.

“We are now coming back over 20 years later to take a new look at some of the data that was never published and

finish the story,” said Glyn Collinson, lead author of a recent paper about Ganymede's magnetosphere at NASA’s

Goddard Space Flight Center in Greenbelt, Maryland. “We found there’s a whole piece no one knew about.”

The new results showed a stormy scene: particles blasted off the moon’s icy surface as a result of incoming plasma

rain, and strong flows of plasma pushed between Jupiter and Ganymede due to an explosive magnetic event

occurring between the two bodies’ magnetic environments. Scientists think these observations could be key to

unlocking the secrets of the moon, such as why Ganymede’s auroras are so bright.

In 1996, shortly after arriving at Jupiter, Galileo made a surprising discovery: Ganymede had its own magnetic field.

While most planets in our solar system, including Earth, have magnetic environments — known as magnetospheres

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— no one expected a moon to have one. Between 1996 and 2000, Galileo made six targeted flybys of Ganymede,

with multiple instruments collecting data on the moon’s magnetosphere. These included the spacecraft's Plasma

Subsystem, or PLS, which measured the density, temperature and direction of the plasma — excited, electrically

charged gas — flowing through the environment around Galileo. New results, recently published in the journal

Geophysical Research Letters, reveal interesting details about the magnetosphere's unique structure.

We know that Earth’s magnetosphere — in addition to helping make compasses work and causing auroras — is key

to in sustaining life on our planet, because it helps protect our planet from radiation coming from space. Some

scientists think Earth’s magnetosphere was also essential for the initial development of life, as this harmful radiation

can erode our atmosphere. Studying magnetospheres throughout the solar system not only helps scientists learn

about the physical processes affecting this magnetic environment around Earth, it helps us understand the

atmospheres around other potentially habitable worlds, both in our own solar system and beyond.

Flying past Ganymede, Galileo was continually pummeled by high-energy particles — a battering the moon is also

familiar with. Plasma particles accelerated by the Jovian magnetosphere, continually rain down on Ganymede’s

poles, where the magnetic field channels them toward the surface. The new analysis of Galileo PLS data showed

plasma being blasted off the moon’s icy surface due to the incoming plasma rain. “There are these particles flying

out from the polar regions, and they can tell us something about Ganymede’s atmosphere, which is very thin,” said

Bill Paterson, a co-author of the study at NASA Goddard, who served on the Galileo PLS team during the mission.

“It can also tell us about how Ganymede’s auroras form.”

Ganymede has auroras, or northern and southern lights, just like Earth does. However, unlike our planet, the

particles causing Ganymede’s auroras come from the plasma surrounding Jupiter, not the solar wind. When

analyzing the data, the scientists noticed that during its first Ganymede flyby, Galileo fortuitously crossed right over

Ganymede’s auroral regions, as evidenced by the ions it observed raining down onto the surface of the moon’s

polar cap. By comparing the location where the falling ions were observed with data from Hubble, the scientists

were able to pin down the precise location of the auroral zone, which will help them solve mysteries, such as what

causes the auroras.

As it cruised around Jupiter, Galileo also happened to fly right through an explosive event caused by the tangling

and snapping of magnetic field lines. This event, called magnetic reconnection, occurs in magnetospheres across

our solar system. For the first time, Galileo observed strong flows of plasma pushed between Jupiter and Ganymede

due to a magnetic reconnection event occurring between the two magnetospheres. It’s thought that this plasma

pump is responsible for making Ganymede’s auroras unusually bright.

Future study of the PLS data from that encounter may yet provide new insights related to subsurface oceans

previously determined to exist within the moon using data from both Galileo and the Hubble Space Telescope.

Source: NASA Return to Contents

This image of Ganymede, one

of Jupiter's moons and the

largest moon in our solar

system, was taken by NASA's

Galileo spacecraft. Credits:

NASA

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3. Twin Spacecraft to Weigh in on Earth's Changing Water

Illustration of the NASA's Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) spacecraft, which will track

changes in the distribution of Earth’s mass, providing insights into climate, Earth system processes and the impacts of

some human activities. GRACE-FO is a partnership between NASA and the German Research Centre for Geosciences.

Credits: NASA/JPL-Caltech

A pair of new spacecraft that will observe our planet’s ever-changing water cycle, ice sheets, and crust is in

final preparations for a California launch no earlier than Saturday, May 19. The Gravity Recovery and Climate

Experiment Follow-On (GRACE-FO) mission, a partnership between NASA and the German Research Centre for

Geosciences (GFZ), will take over where the first GRACE mission left off when it completed its 15-year mission

in 2017.

GRACE-FO will continue monitoring monthly changes in the distribution of mass within and among Earth’s

atmosphere, oceans, land and ice sheets, as well as within the solid Earth itself. These data will provide unique

insights into Earth’s changing climate, Earth system processes and even the impacts of some human activities,

and will have far-reaching benefits to society, such as improving water resource management.

“Water is critical to every aspect of life on Earth – for health, for agriculture, for maintaining our way of living,”

said Michael Watkins, GRACE-FO science lead and director of NASA’s Jet Propulsion Laboratory (JPL) in

Pasadena, California. “You can’t manage it well until you can measure it. GRACE-FO provides a unique way to

measure water in many of its phases, allowing us to manage water resources more effectively.”

Like GRACE, GRACE-FO will use an innovative technique to observe something that can’t be seen directly from

space. It uses the weight of water to measure its movement – even water hidden far below Earth’s surface.

GRACE-FO will do this by very precisely measuring the changes in the shape of Earth’s gravity field caused by

the movement of massive amounts of water, ice, and solid Earth.

“When water is underground, it’s impossible to directly observe from space. There’s no picture you can take or

radar you can bounce off the surface to measure changes in that deep water,” said Watkins. “But it has mass,

and GRACE-FO is almost the only way we have of observing it on large scales. Similarly, tracking changes in

the total mass of the polar ice sheets is also very difficult, but GRACE-FO essentially puts a ‘scale’ under them

to track their changes over time.”

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A Legacy of Discoveries

GRACE-FO will extend the GRACE data record an additional five years and expand its legacy of scientific

achievements. GRACE chronicled the ongoing loss of mass from the Greenland and Antarctic ice sheets and

mountain glaciers. That wealth of data shed light on the key processes, short-term variability, and long-term

trends that impact sea level rise, helping to improve sea level projections. The estimates of total water storage

on land derived from GRACE data, from groundwater changes in deep aquifers to changes in soil moisture and

surface water, are giving water managers new tools to measure the impact of droughts and monitor and

forecast floods.

GRACE data also have been used to infer changes in deep ocean currents, a driving force in Earth’s climate. Its

atmospheric temperature profile data, derived from measurements of how signals from the constellation of

GPS satellites were bent as they traveled through the atmosphere and received by antennas on the GRACE

satellites, have contributed to U.S. and European weather forecast products. GRACE data have even been

used to measure changes within the solid Earth itself, including the response of Earth’s crust to the retreat of

glaciers since the last Ice Age, and the impact of large earthquakes.

According to Frank Webb, GRACE-FO project scientist at JPL, the new mission will provide invaluable

observations of long-term climate-related mass changes.

“The only way to know for sure whether observed multi-year trends represent long-term changes in mass

balance is to extend the length of the observations,” Webb said.

An Orbiting Cat and Mouse

Like its predecessors, the two identical GRACE-FO satellites will function as a single instrument. The satellites

orbit Earth about 137 miles (220 kilometers) apart, at an initial altitude of about 305 miles (490 kilometers).

Each satellite continually sends microwave signals to the other to accurately measure changes in the distance

between them. As they fly over a massive Earth feature, such as a mountain range or underground aquifer,

the gravitational pull of that feature tugs on the satellites, changing the distance separating them. By tracking

changes in their separation distance with incredible accuracy - to less than the thickness of a human hair - the

satellites are able to map these regional gravity changes.

A global positioning system receiver is used to track each spacecraft’s position relative to Earth’s surface, and

onboard accelerometers record non-gravitational forces on the spacecraft, such as atmospheric drag and solar

radiation. These data are combined to produce monthly maps of the regional changes in global gravity and

corresponding near-surface mass variations, which primarily reflect changes in the distribution of water mass

in Earth’s atmosphere, oceans, land and ice sheets.

In addition, GRACE-FO will test an experimental Laser Ranging Interferometer, an instrument that could

increase the precision of measurements between the two spacecraft, by a factor of 10 or more, for future

missions similar to GRACE. The interferometer, developed by a German/American instrument team, will be the

first in-space demonstration of laser interferometry between satellites.

“The Laser Ranging Interferometer is an excellent example of a great partnership,” said Frank Flechtner, GFZ’s

GRACE-FO project manager. “I’m looking forward to analyzing these innovative inter-satellite ranging data and

their impact on gravity field modeling.”

GRACE-FO will be launched into orbit with five Iridium NEXT communications satellites on a commercially

procured SpaceX Falcon 9 rocket from Vandenberg Air Force Base in California. This unique “rideshare” launch

will first deploy GRACE-FO, then the Falcon 9 second stage will continue to a higher orbit to deploy the Iridium

satellites.

Source: NASA Return to Contents

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The Night Sky

Source: Sky and Telescope Return to Contents

Tuesday, May 1

• May has sprung, but wintry Sirius still twinkles very low

in the west-southwest toward the end of twilight — far to

the left of much brighter Venus. How much longer into the

spring can you keep Sirius in view? In other words, what

will be its date of "heliacal setting" as seen by you?

Wednesday, May 2

• Arcturus is the brightest star high in the east these

evenings. Spica shines about three fists at arm's length to

its lower right. To the right of Spica by half that distance is

the distinctive four-star constellation of Corvus, the Crow.

Far below Arcturus and Spica, Jupiter glares.

Thursday, May 3

• These spring nights, the long, dim sea serpent Hydra

snakes level far across the southern sky. Find his head, a

rather dim asterism about the width of your thumb at

arm's length, in the southwest. (It's lower right of Regulus

by about two fists at arm's length. Also, a line from Castor

through Pollux points to it about 2½ fists away.) Lower

left of this is Hydra's heart, orange Alphard. Hydra's tail

stretches all the way to Libra in the southeast. Hydra's

actual star pattern, from forehead to tail-tip, is 95° long.

• Now that the Moon is gone from the sky after dark, try for the Ghost of Jupiter planetary nebula, magnitude 7.7, in

mid-Hydra (NGC 3242). At that brightness it's a potential binocular target about as easy or difficult as Neptune; it's so

tiny that at low power it's easily mistaken for a star.

In a telescope at medium or high power, it does looks sort of like Jupiter's weak ghost dimly haunting the dark.

• Back at the real Jupiter, Europa slips into eclipse by Jupiter's shadow around 11:55 p.m. EDT. A telescope will show

Europa gradually disappearing barely off Jupiter's western edge — since the planet is barely 5 days before opposition.

Jupiter's Great Red Spot crosses the planet's central meridian around 10:18 p.m. EDT. This timing is good for the

Eastern and Atlantic time zones. Farther west, Jupiter is still low or hasn't risen yet.

Friday, May 4

• Summer is seven weeks away, but the Summer Triangle is beginning to make its appearance in the east, one star

after another. The first in view is Vega. It's already shining low in the northeast as twilight fades away.

Next up is Deneb, lower left of Vega by two or three fists at arm's length. Deneb takes about an hour to appear after

Vega does, depending on your latitude.

The third is Altair, which shows up far to their lower right by midnight.

• As dawn begins on Saturday morning May 5th, the waning gibbous Moon shines between Saturn and Mars. Saturn is

to the Moon's right, and Mars to the Moon's lower left.

Venus shines between Aldebaran and the Pleiades in late twilight. But a week later the stars have sunk lower, while Venus stays at

nearly the same height. (The blue 10° scale is about the size of your fist held at arm's length.)

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ISS Sighting Opportunities (from Denver)

Date Visible Max Height Appears Disappears

Wed May 2, 4:11 AM 3 min 14° 12° above SSE 10° above E

Thu May 3, 4:53 AM 3 min 72° 19° above SW 34° above ENE

Fri May 4, 4:03 AM 2 min 34° 34° above SE 16° above ENE

Sat May 5, 3:13 AM < 1 min 12° 12° above E 10° above E

Sighting information for other cities can be found at NASA’s Satellite Sighting Information

NASA-TV Highlights (all times Eastern Time Zone)

Tuesday, May 1

1 p.m., 6 p.m. and 10 p.m. - The Smithsonian National Air and Space Museum Presents -- What’s New

in Aerospace? Chasing New Horizons: Inside the Epic First Mission to Pluto (NTV-1 (Public))

2 p.m. - Replay of the Pre-Launch Briefing on NASA’s Next Earth-Observing Mission: The Gravity

Recovery and Climate Experiment Follow-On (GRACE-FO) Mission (all channels)

4 p.m. and 8 p.m. - RNASA Space Awards Gala 2018 (all channels)

Wednesday, May 2

7 a.m., - ISS Expedition 55 In-Flight Event for JAXA with Makuhari New City, Chiba Prefecture, Japan

and Flight Engineer Norishige Kanai of the Japan Aerospace Exploration Agency (JAXA) (starts at 7:20

a.m.) (all channels)

10 a.m. - Coverage of the Release of the SpaceX/Dragon CRS-14 Cargo Craft from the ISS (Release is

scheduled 10:22 a.m. EDT) (all channels)

12 p.m. - ISS Expedition 55 Educational In-Flight Event with the Champlain Valley School District in

Hinesburg, Vermont and Flight Engineers Drew Feustel and Scott Tingle of NASA (starts at 12:20 p.m.)

(all channels)

Thursday, May 3

4 p.m. - Pre-launch briefing for InSight Mars Lander (all channels)

Saturday, May 5

6:30 a.m. - InSight Mars Lander launch coverage from Vandenberg Air Force Base in California (Launch

scheduled for 7:05) (all channels)

Watch NASA TV online by going to the NASA website. Return to Contents

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Space Calendar

May 01 - Comet P/2011 CR42 (Catalina) Closest Approach To Earth (1.537 AU)

May 01 - Comet 330P/Catalina At Opposition (4.022 AU)

May 01 - Amor Asteroid 2018 DX3 Near-Earth Flyby (0.081 AU)

May 01 - Asteroid 4330 Vivaldi Closest Approach To Earth (1.319 AU)

May 01 - Asteroid 51828 Ilanramon Closest Approach To Earth (2.011 AU)

May 01 - Asteroid 13688 Oklahoma Closest Approach To Earth (2.134 AU)

May 01 - Colloquium: The Dark Matter in the Universe, Greenbelt, Maryland

May 01 - Colloquium: Robots Under the Ice, and One Day, In Space?, Tucson, Arizona

May 01-03 - Meeting: Mercury - Current and Future Science of the Innermost Planet, Columbia, Maryland

May 02 - Gaofen 5 (GF 5) CZ-4C Launch

May 02 - Comet 334P/NEAT At Opposition (3.588 AU)

May 02 - [Apr 23] Apollo Asteroid 2018 HB1 Near-Earth Flyby (0.026 AU)

May 02 - Asteroid 9885 Linux Closest Approach To Earth (1.447 AU)

May 02 - Asteroid 4047 Chang'E Closest Approach To Earth (1.852 AU)

May 02 - Asteroid 5471 Tunguska Closest Approach To Earth (1.880 AU)

May 02 - Asteroid 16626 Thumper Closest Approach To Earth (1.928 AU)

May 02 - Asteroid 2099 Opik Closest Approach To Earth (2.044 AU)

May 02 - Asteroid 9860 Archaeopteryx Closest Approach To Earth (2.146 AU)

May 02 - Colloquium: Swimming in Martian Lakes, Greenbelt, Maryland

May 02 - Lecture: The Mid-plane of the Asteroid Belt, Ithaca, New York

May 02-03 - 22nd Annual Improving Space Operations Workshop, San Antonio, Texas

May 02-04 - Workshop: Cosmic Rays - The Salt of the Star Formation Recipe, Florence, Italy

May 02-04 - 3rd Group on Earth Observations (GEO) Data Providers Workshop, Frascati, Italy

May 02-04 - SOFIA Workshop 2018, Stuttgart, Germany

May 03 - Comet 313P/Gibbs Closest Approach To Earth (2.708 AU)

May 03 - Comet C/2017 E3 (PANSTARRS) At Opposition (5.365 AU)

May 03 - Amor Asteroid 2015 JP Near-Earth Flyby (0.097 AU)

May 03 - Asteroid 10866 Peru Closest Approach To Earth (1.193 AU)

May 03 - Asteroid 4122 Ferrari Closest Approach To Earth (1.442 AU)

May 03 - Asteroid 9134 Encke Closest Approach To Earth (1.909 AU)

May 03 - Asteroid 3325 TARDIS Closest Approach To Earth (2.177 AU)

May 03 - Asteroid 13677 Alvin Closest Approach To Earth (2.373 AU)

May 03 - Asteroid 13897 Vesuvius Closest Approach To Earth (2.960 AU)

May 03 - Lecture: Prospects for Unseen Planets beyond Neptune, Ithaca, New York

May 03 - Seminar: Linking Protoplanetary Disk Chemistry with Exoplanetary Compositions, Houston, Texas

May 04 – Space Day/Star Wars Day

May 04 - Comet 37P/Forbes Perihelion (1.610 AU)

Source: JPL Space Calendar Return to Contents

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Food for Thought

Astronomers Witness Galaxy Megamerger

Cosmic pileup forging galaxy cluster in the early universe

Artist impression of the 14 galaxies detected by ALMA as they appear in the very early, very distant universe. These

galaxies are in the process of merging and will eventually form the core of a massive galaxy cluster.

Credit: NRAO/AUI/NSF; S. Dagnello

Using the Atacama Large Millimeter/submillimeter Array (ALMA), an international team of scientists has

uncovered a startlingly dense concentration of 14 galaxies that are poised to merge, forming the core of what

will eventually become a colossal galaxy cluster

This tightly bound galactic smashup, known as a protocluster, is located approximately 12.4 billion light-years

away, meaning its light started traveling to us when the universe was only 1.4 billion years old, or about a

tenth of its present age. Its individual galaxies are forming stars as much as 1,000 times faster than our home

galaxy and are crammed inside a region of space only about three times the size of the Milky Way. The

resulting galaxy cluster will eventually rival some of the most massive clusters we see in the universe today.

The results are published in the journal Nature, presented in a paper titled “A massive core for a cluster of

galaxies at a redshift of 4.3,” by T.B. Miller, et al.[www.nature.com]

“Having caught a massive galaxy cluster in throes of formation is spectacular in and of itself,” said Scott

Chapman, an astrophysicist at Dalhousie University in Halifax, Canada, who specializes in observational

cosmology and studies the origins of structure in the universe and the evolution of galaxies.

“But, the fact that this is happening so early in the history of the universe poses a formidable challenge to our

present-day understanding of the way structures form in the universe,” he said.

During the first few million years of cosmic history, normal matter and dark matter began to aggregate into

larger and larger concentrations, eventually giving rise to galaxy clusters, the largest objects in the known

universe. With masses comparable to a million billion suns, clusters may contain as many as a thousand

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galaxies, vast amounts of dark matter, gargantuan black holes, and X-ray emitting gas that reaches

temperatures of over a million degrees.

Current theory and computer models suggest that protoclusters as massive as the one observed by ALMA,

however, should have taken much longer to evolve.

“How this assembly of galaxies got so big so fast is a bit of a mystery, it wasn’t built up gradually over billions

of years, as astronomers might expect,” said Tim Miller, a doctoral candidate at Yale University and coauthor

on the paper. “This discovery provides an incredible opportunity to study how galaxy clusters and their

massive galaxies came together in these extreme environments.”

This particular galactic protocluster, designated SPT2349-56, was first observed as a faint smudge of

millimeter-wavelength light in 2010 with the National Science Foundation’s South Pole Telescope. Follow-up

observations with the Atacama Pathfinder Experiment (APEX) telescope helped confirm that it was in fact an

extremely distant galactic source and worthy of follow-up observations with ALMA. ALMA’s superior resolution

and sensitivity allowed astronomers to distinguish no fewer than 14 individual objects in a shockingly small

region of space, confirming the object was the archetypical example of a protocluster in a very early stage of

development.

This cluster’s extreme distance and clearly defined components offer astronomers an unprecedented

opportunity to study some of the first steps of cluster formation less than 1.5 billion years after the Big Bang.

By using the ALMA data as the starting conditions for sophisticated computer simulations, the researchers

were able to demonstrate how this current collection of galaxies will likely grow and evolve over billions of

years.

“ALMA gave us, for the first time, a clear starting point to predict the evolution of a galaxy cluster. Over time,

the 14 galaxies we observed will stop forming stars and will collide and coalesce into a single gigantic galaxy,”

said Chapman.

Source: National Radio Astronomy Observatory Return to Contents

Zooming in to the galaxies discovered by ALMA that are

evolving into a galaxy cluster. The outer field is from data taken by the Hershel Space Observatory.

The middle image -- a portion of a much-wider survey by NSF's South Pole Telescope -- uncovered the distant galactic source that was

studied by ALMA to reveal the 14 galaxies.

Credit: ALMA (ESO/NAOJ/NRAO),

T. Miller & S. Chapman et al.; Herschel; South Pole Telescope;

(NRAO/AUI/NSF) B. Saxton

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Space Image of the Week

NGC 7635: The Bubble Nebula Image Credit: NASA, ESA, Hubble Heritage Team - Reprocessing by Maksim Kakitsev

Explanation: Blown by the wind from a massive star, this interstellar apparition has a surprisingly familiar shape. Cataloged as NGC 7635, it is also known simply as The Bubble Nebula. Although it looks delicate, the 7 light-year diameter bubble offers evidence of violent processes at work. Above and left of the Bubble's center is a hot, O-type star, several hundred thousand times more luminous and some 45 times more massive than the Sun. A fierce stellar wind and intense radiation from that star has blasted out the structure of glowing gas against denser material in a surrounding molecular cloud. The intriguing Bubble Nebula and associated cloud complex lie a mere 7,100 light-years away toward the boastful constellation Cassiopeia. This sharp, tantalizing view of the cosmic bubble is a composite of Hubble Space Telescope image data from 2016, reprocessed to present the nebula's intense narrowband emission in an approximate true color scheme.

Source: NASA APOD Return to Contents