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Tuesday, December 2, 2014

The Disintegration of Comet ISON


Some had hoped comet ISON would be the comet of the century, lighting Earth’s skies during the latter months of 2013. Instead, it was barely visible for ground-based observers, but the Solar and Heliospheric Observatory (SOHO) had a ring-side seat to watch its disintegration.

This image is a montage spanning three days from 28–30 November 2013. The comet enters the image at the lower right, passes round the Sun and exits the frame towards the upper right. The bright star to the lower left is the red supergiant star Antares.

Astronomers had been tracking the comet for more than a year as it edged closer to the Sun, and by late November it had passed into the field of view of SOHO’s LASCO C3 camera. It was to skim the Sun, just 1,165,000 km above the fiery surface.

This is approximately 50 times closer to the Sun than innermost planet Mercury, and the comet was officially termed a ‘sungrazer’. If it survived the encounter it was expected to become extremely bright and be a well-placed object, visible to the naked eye in Earth’s night sky.

Calculations based on its orbit show that ISON began its journey towards the Sun about 3 million years ago, dislodged from its distant orbit by a passing star. Now, its fate would be sealed within days.

On 27 November, the comet brightened dramatically by a factor of about ten. Yet just before it reached closest approach to the Sun, it began to fade. This was a strong indicator that the heart of the comet, the icy nucleus, had broken up. Many expected it would disperse completely but, at first, it looked as if they were wrong.

Comet ISON appeared to survive the close approach, emerging on the other side of the Sun. Some still hoped for a bright display in the night skies. But they were to be disappointed. Quickly, the comet began to disappear. A recent analysis of SOHO data showed that the nucleus had indeed disintegrated just before closest approach to the Sun. Nothing appreciable was left of it, just a lot of dust and vapor.

The disintegration of comet ISON provided scientists with an exceptional chance to see a comet inside and out. Another rare opportunity is being provided by comet 67P/Churyumov-Gerasimenko. ESA’s Rosetta spacecraft caught up with this comet early in August 2014 and deployed the lander Philae to the surface in November. The orbiter will accompany comet 67P/C-G along its orbit and through its closest approach to the Sun, which takes it between the orbits of Mars and Earth. While this comet is unlikely to suffer the same fate as comet ISON, it will provide an unsurpassed insight into the nature of comets.

Image credit: ESA/NASA

Thursday, November 27, 2014

NGC 3532


The MPG/ESO 2.2-meter telescope at ESO’s La Silla Observatory in Chile captured this richly colorful view of the bright star cluster NGC 3532. Some of the stars still shine with a hot bluish color, but many of the more massive ones have become red giants and glow with a rich orange hue.

Image credit: ESO/G. Beccari

Note: For more information, see A Colorful Gathering of Middle-Aged Stars.

Saturday, November 22, 2014

Europa Remastered


The puzzling, fascinating surface of Jupiter's icy moon Europa looms large in this newly-reprocessed color view, made from images taken by NASA's Galileo spacecraft in the late 1990s. This is the color view of Europa from Galileo that shows the largest portion of the moon's surface at the highest resolution.

The view was previously released as a mosaic with lower resolution and strongly enhanced color (see PIA02590). To create this new version, the images were assembled into a realistic color view of the surface that approximates how Europa would appear to the human eye.

The scene shows the stunning diversity of Europa's surface geology. Long, linear cracks and ridges crisscross the surface, interrupted by regions of disrupted terrain where the surface ice crust has been broken up and re-frozen into new patterns.

Color variations across the surface are associated with differences in geologic feature type and location. For example, areas that appear blue or white contain relatively pure water ice, while reddish and brownish areas include non-ice components in higher concentrations. The polar regions, visible at the left and right of this view, are noticeably bluer than the more equatorial latitudes, which look more white. This color variation is thought to be due to differences in ice grain size in the two locations.

Images taken through near-infrared, green and violet filters have been combined to produce this view. The images have been corrected for light scattered outside of the image, to provide a color correction that is calibrated by wavelength. Gaps in the images have been filled with simulated color based on the color of nearby surface areas with similar terrain types.

This global color view consists of images acquired by the Galileo Solid-State Imaging (SSI) experiment on the spacecraft's first and fourteenth orbits through the Jupiter system, in 1995 and 1998, respectively. Image scale is 1 mile (1.6 kilometers) per pixel. North on Europa is at right.

Image credit: NASA/JPL-Caltech/SETI Institute

Note: For more information, see NASA Issues 'Remastered' View of Jupiter's Moon Europa.

Friday, November 21, 2014

Four Globular Clusters in Fornax


This NASA/ESA Hubble Space Telescope image shows four globular clusters in the dwarf galaxy Fornax.

New observations of the clusters – large balls of stars that orbit the centers of galaxies – show they are very similar to those found in our galaxy, the Milky Way. The finding is at odds with leading theories on how these clusters form – in these theories, globular clusters should be nestled among large quantities of old stars – and so the mystery of how these objects came to exist deepens.

Left to right: Fornax 1, Fornax 2, Fornax 3 and Fornax 5. Their positions within the galaxy are shown in image heic1425g.

Image credit: NASA, ESA, S. Larsen (Radboud University, the Netherlands)

Note: For more information, see The Riddle of the Missing Stars - Hubble Observations Cast Further Doubt on How Globular Clusters Formed.

Thursday, November 20, 2014

Simulation of a Large Scale Structure


This very detailed simulation of large scale structure was created as part of the Illustris simulation. The distribution of dark matter is shown in blue and the gas distribution in orange. This simulation is for the current state of the Universe and is centered on a massive galaxy cluster. The region shown is about 300 million light-years across.

Illustration credit: Illustris Collaboration

Note: For more information, see Spooky Alignment of Quasars Across Billions of Light-Years.

Wednesday, November 19, 2014

Geological Map of Vesta


This high-resolution geological map of Vesta is derived from Dawn spacecraft data. Brown colors represent the oldest, most heavily cratered surface. Purple colors in the north and light blue represent terrains modified by the Veneneia and Rheasilvia impacts, respectively. Light purples and dark blue colors below the equator represent the interior of the Rheasilvia and Veneneia basins. Greens and yellows represent relatively young landslides or other downhill movement and crater impact materials, respectively. This map unifies 15 individual quadrangle maps published this week in a special issue of Icarus. Map is a Mollweide projection, centered on 180 degrees longitude using the Dawn Claudia coordinate system.

Map credit: NASA/JPL-Caltech/ASU

Note: For more information, see PIA18789: Geological Time Scale of Vesta and Geologic Maps of Vesta from NASA's Dawn Mission Published.

Tuesday, November 18, 2014

Philae Drifting Across Comet 67P/Churyumov-Gerasimenko


These incredible images show the breathtaking journey of Rosetta’s Philae lander as it approached and then rebounded from its first touchdown on Comet 67P/Churyumov–Gerasimenko on 12 November 2014.

The mosaic comprises a series of images captured by Rosetta’s OSIRIS camera over a 30 minute period spanning the first touchdown. The time of each of image is marked on the corresponding insets and is in GMT. A comparison of the touchdown area shortly before and after first contact with the surface is also provided.

The images were taken with Rosetta’s OSIRIS narrow-angle camera when the spacecraft was 17.5 km from the comet center, or roughly 15.5 km from the surface. They have a resolution of 28 cm/pixel and the enlarged insets are 17 x 17 m.

From left to right, the images show Philae descending towards and across the comet before touchdown. The image taken after touchdown, at 15:43 GMT, confirms that the lander was moving east, as first suggested by the data returned by the CONSERT experiment, and at a speed of about 0.5 m/s.

The final location of Philae is still not known, but after touching down and bouncing again at 17:25 GMT, it reached there at 17:32 GMT. The imaging team is confident that combining the CONSERT ranging data with OSIRIS and navcam images from the orbiter and images from near the surface and on it from Philae’s ROLIS and CIVA cameras will soon reveal the lander’s whereabouts.

The insets are provided separately via the blog: OSIRIS spots Philae drifting across the comet.

Image credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

Note: For more information, see:
* PIA18875: First Touchdown Site of Comet Lander
* PIA18879: First Panoramic View from Comet Lander
* PIA18897: Rosetta Lander Captured Before/After Bounce
* First Touchdown
* Philae Spotted by Rosetta After First Landing
* Searching for Philae
* First Comet Panoramic
* First Touchdown Close-Up 1
* Three Touchdowns for Rosetta's Lander
* Pioneering Philae Completes Main Mission Before Hibernation
* Rosetta's 'Philae' Makes Historic First Landing on a Comet
* Rosetta's Comet Lander Landed Three Times
* Philae Landing: Acquisition of Signal from Spacecraft and Lander (Video)
* Philae Landing: Touchdown Highlights (Video)
* Philae Touchdown: Lander Status and First Descent Image (Video)
* OSIRIS Spots Philae Drifting Across the Comet

Thursday, November 13, 2014

Comet 67P/Churyumov-Gerasimenko During Philae's Descent


This image of comet 67P/Churyumov-Gerasimenko was acquired by the Philae lander of the European Space Agency's Rosetta mission during Philae's descent toward the comet on November 12, 2014. Philae's ROLIS (ROsetta Lander Imaging System) took the image at 14:38:41 UTC (6:38:41 a.m., PST) at a distance of approximately two miles (three kilometers) from the surface. The landing site is imaged with a resolution of about 10 feet (three meters) per pixel.

The ROLIS instrument is a down-looking imager that acquires images during the descent and doubles as a multi-spectral close-up camera after the landing. The aim of the ROLIS experiment is to study the texture and microstructure of the comet's surface. It was developed by the German Aerospace Center's Institute of Planetary Research, Berlin.

The lander separated from the orbiter at 09:03 UTC (1:03 a.m. PST) for touch down on comet 67P seven hours later.

Rosetta and Philae had been riding through space together for more than 10 years. Philae is the first probe to achieve a soft landing on a comet, and Rosetta is the first to rendezvous with a comet and follow it around the sun. The information collected by Philae at one location on the surface will complement that collected by the Rosetta orbiter for the entire comet.

Image credit: ESA/Rosetta/Philae/DLR

Note: This is the major story for today, and just the ESA and NASA by themselves have numerous news stories, photos and videos available. For more information, see:
* How to Land on a Comet
* PIA18871: Rosetta Mission Selfie at 10 Miles
* PIA18872: Rosetta Mission Selfie at 30 Miles
* PIA18873: Farewell, Philae
* PIA18870: Farewell Shot of Rosetta by Philae Lander
* European Spacecraft Set to Harpoon a Comet Today
* Separation
* Confirmation of Separation of the Philae Lander from Rosetta
* Separation Signal Confirmed
* Farewell Rosetta
* Farewell Philae - Narrow-Angle View (1)
* Farewell Philae - Narrow-Angle View (2)
* Farewell Philae - Wide-Angle View
* Philae Descending to the Comet – Wide-Angle View
* Lander Departure
* ROLIS Descent Image
* Highlights: Rosetta Mission Comet Landing Up to Lander Separation (Video)
* Rosetta and Philae Go for Separation
* Rosetta and Philae Separation Confirmed
* Confirmation of Separation of the Philae Lander from Rosetta
* Touchdown! Rosetta's Philae Probe Lands on Comet

Wednesday, November 12, 2014

Smooth Terrain on Comet 67P/Churyumov-Gerasimenko


A patch of relatively smooth ground on the nucleus surface of comet 67P/Churyumov-Gerasimenko appears in this image taken by the navigation camera on the European Space Agency's Rosetta spacecraft during the second half of October 2014. The spacecraft has been orbiting this comet since August 2014 and will release its lander, Philae, on November 12 to land on the comet's nucleus.

This image was taken from a distance of less than six miles (10 kilometers) from the surface. It is one of a series of images from Rosetta's navigation camera showing the varied and dramatic terrain of the nucleus. Some light contrast enhancements have been made to emphasize certain features and to bring out features in the shadowed areas. In reality, the comet is extremely dark - blacker than coal. The images, taken in black-and-white, are grey-scaled according to the relative brightness of the features observed, which depends on local illumination conditions, surface characteristics and composition of the given area.

Comets are time capsules containing primitive material left over from the epoch when the sun and its planets formed. Rosetta's lander will obtain the first images taken from a comet's surface and will provide the first analysis of a comet's composition by drilling into the surface. Rosetta also will be the first spacecraft to witness at close proximity how a comet changes as it is subjected to the increasing intensity of the sun's radiation. Observations will help scientists learn more about the origin and evolution of our solar system and the role comets may have played in seeding Earth with water, and perhaps even life.

Image credit: ESA/Rosetta/NAVCAM

Note: For more information, see PIA18867: Jagged Horizon on Rosetta's Destination Comet and PIA18869: Rough Terrain on Rosetta's Destination Comet.

Tuesday, November 11, 2014

Ram-Pressure Stripped Galaxy ESO 137-001


The MUSE instrument on ESO’s Very Large Telescope has provided researchers with the best view yet of a spectacular cosmic crash. Observations reveal for the first time the motion of gas as it is ripped out of the galaxy ESO 137-001 as it plows at high speed into a vast galaxy cluster. The results are the key to the solution of a long-standing mystery — why star formation switches off in galaxy clusters.

In this picture the colors show the motions of the gas filaments — red means the material is moving away from Earth compared to the galaxy and blue that it is approaching.

Note that the upper-left and lower-right parts of this picture have been filled in using the Hubble image of this object.

Image credit: ESO/M. Fumagalli

Note: For more information, see MUSE Reveals True Story Behind Galactic Crash.

Friday, November 7, 2014

Protoplanetary Disc Around HL Tauri


This is the sharpest image ever taken by ALMA — sharper than is routinely achieved in visible light with the NASA/ESA Hubble Space Telescope. It shows the protoplanetary disc surrounding the young star HL Tauri. These new ALMA observations reveal substructures within the disc that have never been seen before and even show the possible positions of planets forming in the dark patches within the system.

Image credit: ALMA (ESO/NAOJ/NRAO)

Note: For more information, see Revolutionary ALMA Image Reveals Planetary Genesis.

Tuesday, November 4, 2014

Artist’s Impression of Bright Exozodiacal Light


This artist’s view from an imagined planet around a nearby star shows the brilliant glow of exozodiacal light extending up into the sky and swamping the Milky Way. This light is starlight reflected from hot dust created as the result of collisions between asteroids, and the evaporation of comets. The presence of such thick dust clouds in the inner regions around some stars may pose an obstacle to the direct imaging of Earth-like planets in the future.

Illustration credit: ESO/L. Calçada

Note: For more information, see VLTI Detects Exozodiacal Light.

Friday, October 31, 2014

Sunglint Off of Titan's Kraken Mare


This near-infrared, color mosaic from NASA's Cassini spacecraft shows the sun glinting off of Titan's north polar seas. While Cassini has captured, separately, views of the polar seas (see PIA17470) and the sun glinting off of them (see PIA12481 and PIA18433) in the past, this is the first time both have been seen together in the same view.

The sunglint, also called a specular reflection, is the bright area near the 11 o'clock position at upper left. This mirror-like reflection, known as the specular point, is in the south of Titan's largest sea, Kraken Mare, just north of an island archipelago separating two separate parts of the sea.

This particular sunglint was so bright as to saturate the detector of Cassini's Visual and Infrared Mapping Spectrometer (VIMS) instrument, which captures the view. It is also the sunglint seen with the highest observation elevation so far -- the sun was a full 40 degrees above the horizon as seen from Kraken Mare at this time -- much higher than the 22 degrees seen in PIA18433. Because it was so bright, this glint was visible through the haze at much lower wavelengths than before, down to 1.3 microns.

The southern portion of Kraken Mare (the area surrounding the specular feature toward upper left) displays a "bathtub ring" -- a bright margin of evaporate deposits -- which indicates that the sea was larger at some point in the past and has become smaller due to evaporation. The deposits are material left behind after the methane & ethane liquid evaporates, somewhat akin to the saline crust on a salt flat.

The highest resolution data from this flyby -- the area seen immediately to the right of the sunglint -- cover the labyrinth of channels that connect Kraken Mare to another large sea, Ligeia Mare. Ligeia Mare itself is partially covered in its northern reaches by a bright, arrow-shaped complex of clouds. The clouds are made of liquid methane droplets, and could be actively refilling the lakes with rainfall.

The view was acquired during Cassini's August 21, 2014, flyby of Titan, also referred to as "T104" by the Cassini team.

The view contains real color information, although it is not the natural color the human eye would see. Here, red in the image corresponds to 5.0 microns, green to 2.0 microns, and blue to 1.3 microns. These wavelengths correspond to atmospheric windows through which Titan's surface is visible. The unaided human eye would see nothing but haze, as in PIA12528.

Image credit: NASA/JPL-Caltech/University of Arizona/University of Idaho

Note: For more information, see PIA18433: Sunglint on a Hydrocarbon Lake and Cassini Sees Sunny Seas on Titan.

Thursday, October 30, 2014

Artist’s Impression of the Double-Star System GG Tauri-A


This artist’s impression shows the dust and gas around the double star system GG Tauri-A. Researchers using ALMA have detected gas in the region between two discs in this binary system. This may allow planets to form in the gravitationally perturbed environment of the binary. Half of Sun-like stars are born in binary systems, meaning that these findings will have major consequences for the hunt for exoplanets.

Illustration credit: ESO/L. Calçada

Note: For more information, see Planet-Forming Lifeline Discovered in a Binary Star System.

Sunday, October 26, 2014

Exocomets Around Beta Pictoris


This artist’s impression shows exocomets orbiting the star Beta Pictoris. Astronomers analyzing observations of nearly 500 individual comets made with the HARPS instrument at ESO’s La Silla Observatory have discovered two families of exocomets around this nearby young star. The first consists of old exocomets that have made multiple passages near the star. The second family, shown in this illustration, consists of younger exocomets on the same orbit, which probably came from the recent breakup of one or more larger objects.

Illustration credit: ESO/L. Calçada

Note: For more information, see Two Families of Comets Found Around Nearby Star.

Saturday, October 25, 2014

Comet 67P/Churyumov-Gerasimenko's Jets


This image of 67P/Churyumov-Gerasimenko was taken by the Optical, Spectroscopic, and Infrared Remote Imaging System, Rosetta's main onboard scientific imaging system, on September 10, 2014. Jets of cometary activity can be seen along almost the entire body of the comet.

Image credit: ESA/Rosetta/MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

Note: For more information, see PIA18835: Rosetta Comet Spreads its Jets, Comet activity – 10 September 2014, Rosetta's Comet Scrambling Its Jets(JPL), and Rosetta Comet Scrambles its Jets (NASA Science News).

Friday, October 24, 2014

Six Images by Chandra


Chandra Archive Collection: Six images that combine Chandra data with those from other telescopes.

With the passing of Chandraʼs 15th anniversary, the Chandra Data Archive, which houses all of the missionʼs data, continues to grow each successive year. These images – that include a wide range of astronomical objects -- combine X-rays from Chandraʼs archive with data from other telescopes. This technique of creating “multi-wavelength” images allows scientists and the public to see how X-rays fit with data of other types of light, such as optical, radio, and infrared.

PSR B1509-58 (upper left)
Pareidolia is the psychological phenomenon where people see recognizable shapes in clouds, rock formations, or otherwise unrelated objects or data. When Chandra's image of PSR B1509-58, a spinning neutron star surrounded by a cloud of energetic particles, was released in 2009, it quickly gained attention because many saw a hand-like structure in the X-ray emission. In this new image of the system, X-rays from Chandra in gold are seen along with infrared data from NASA's Wide-field Infrared Survey Explorer (WISE) telescope in red, green, and blue. Pareidolia may strike again in this image as some people report seeing a shape of a face in WISE's infrared data.

RCW 38 (upper right)
A young star cluster about 5,500 light years from Earth, RCW 38 provides astronomers a chance to closely examine many young, rapidly evolving stars at once. In this composite image, X-rays from Chandra are blue, while infrared data from NASA's Spitzer Space Telescope are orange and additional infrared data from the 2MASS survey appears white. There are many massive stars in RCW 38 that will likely explode as supernovas. Astronomers studying RCW 38 are hoping to better understand this environment as our Sun was likely born into a similar stellar nursery.

Hercules A (middle left):
Some galaxies have extremely bright cores, suggesting that they contain a supermassive black hole that is pulling in matter at a prodigious rate. Astronomers call these "active galaxies," and Hercules A is one of them. In visible light (colored red, green and blue, with most objects appearing white), Hercules A looks like a typical elliptical galaxy. In X-ray light, however, Chandra detects a giant cloud of multimillion-degree gas (purple). This gas has been heated by energy generated by the infall of matter into a black hole at the center of Hercules A that is over 1,000 times as massive as the one in the middle of the Milky Way. Radio data (blue) show jets of particles streaming away from the black hole. The jets span a length of almost one million light years.

Kes 73 (middle right):
The supernova remnant Kes 73, located about 28,000 light years away, contains a so-called anomalous X-ray pulsar, or AXP, at its center. Astronomers think that most AXPs are magnetars, which are neutron stars with ultra-high magnetic fields. Surrounding the point-like AXP in the middle, Kes 73 has an expanding shell of debris from the supernova explosion that occurred between about 750 and 2100 years ago, as seen from Earth. The Chandra data (blue) reveal clumpy structures along one side of the remnant, and appear to overlap with infrared data (orange). The X-rays partially fill the shell seen in radio emission (red) by the Very Large Array. Data from the Digitized Sky Survey optical telescope (white) show stars in the field-of-view.

Mrk 573 (lower left):
Markarian 573 is an active galaxy that has two cones of emission streaming away from the supermassive black hole at its center. Several lines of evidence suggest that a torus, or doughnut of cool gas and dust may block some of the radiation produced by matter falling into supermassive black holes, depending on how the torus is oriented toward Earth. Chandra data of Markarian 573 suggest that its torus may not be completely solid, but rather may be clumpy. This composite image shows overlap between X-rays from Chandra (blue), radio emission from the VLA (purple), and optical data from Hubble (gold).

NGC 4736 (lower right):
NGC 4736 (also known as Messier 94) is a spiral galaxy that is unusual because it has two ring structures. This galaxy is classified as containing a "low ionization nuclear emission region," or LINER, in its center, which produces radiation from specific elements such as oxygen and nitrogen. Chandra observations (gold) of NGC 4736, seen in this composite image with infrared data from Spitzer (red) and optical data from Hubble and the Sloan Digital Sky Survey (blue), suggest that the X-ray emission comes from a recent burst of star formation. Part of the evidence comes from the large number of point sources near the center of the galaxy, showing that strong star formation has occurred. In other galaxies, evidence points to supermassive black holes being responsible for LINER properties. Chandra's result on NGC 4736 shows LINERs may represent more than one physical phenomenon.

Image credit: NASA/CXC/SAO

Note: For more information, see Chandra Archive Collection: Chandra's Archives Come to Life.

Thursday, October 23, 2014

NGC 1291


This image from NASA's Spitzer Space Telescope, taken in infrared light, shows where the action is taking place in galaxy NGC 1291. The outer ring, colored red in this view, is filled with new stars that are igniting and heating up dust that glows with infrared light. The stars in the central area produce shorter-wavelength infrared light than that seen in the ring, and are colored blue. This central area is where older stars live, having long ago gobbled up the available gas supply, or fuel, for making new stars.

The galaxy is about 12 billion years old and is located in the Eridanus constellation. It is known as a barred galaxy because a central bar of stars (which looks like a blue "S" in this view) dominates its center.

When galaxies are young and gas-rich, stellar bars drive gas toward the center, feeding star formation. Over time, as the star-making fuel runs out, the central regions become quiescent and star-formation activity shifts to the outskirts of a galaxy. There, spiral density waves and resonances induced by the central bar help convert gas to stars. The outer ring, seen here in red, is one such resonance location, where gas has been trapped and ignited into a star-forming frenzy.

Image credit: NASA/JPL-Caltech

Note: For more information, see Galactic Wheel of Life Shines in Infrared.

Thursday, October 16, 2014

Artist's Illustration of a Galactic Protocluster


This artist’s impression depicts the formation of a galaxy cluster in the early Universe. The galaxies are vigorously forming new stars and interacting with each other. Such a scene closely resembles the Spiderweb Galaxy (formally known as MRC 1138-262) and its surroundings, which is one of the best-studied protoclusters.

Illustration credit: ESO/M. Kornmesser

Note: For more information, see Construction Secrets of a Galactic Metropolis.

Saturday, October 11, 2014

Weather Map for WASP-43b


In this artist's illustration the Jupiter-sized planet WASP-43b orbits its parent star in one of the closest orbits ever measured for an exoplanet of its size – with a year lasting just 19 hours.

The planet is tidally locked, meaning it keeps one hemisphere facing the star, just as the Moon keeps one face toward Earth.

The color scale on the planet represents the temperature across its atmosphere. This is based on data from a recent study that mapped the temperature of WASP-43b in more detail than has been done for any other exoplanet.

Image credit: NASA, ESA, and Z. Levay (STScI)

Note: For more information, see Hubble Reveals Most Detailed Exoplanet Weather Map Ever.

Friday, October 10, 2014

Boulder Cheops


This image of the surface of Comet 67P/Churyumov-Gerasimenko was taken by Rosetta’s OSIRIS narrow-angle camera on 19 September 2014, from a distance of 28.5 km.

The image features a large boulder casting a long shadow on the surface of the comet. The boulder has a maximum dimension of about 45 meters and is the largest structure within a group of boulders located on the lower side of the comet’s larger lobe. This cluster of boulders reminded scientists of the famous pyramids at Giza near Cairo in Egypt, and thus it has been named Cheops for the largest of those pyramids, the Great Pyramid, which was built as a tomb for the pharaoh Cheops (also known as Kheops or Khufu) around 2550 BC.

Image credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

Grooves on Asteroid 21 Lutetia


A portion of asteroid Lutetia, looking into the 55 km-wide Massilia crater (red circular outline) with the North Pole Crater Cluster (NPCC) in the distance (purple outline). The grooves (or ‘lineaments’) are colored according to the crater to which they are associated, i.e. red for Massilia and purple for NPCC. The blue lineaments are associated with the ‘Suspicio’ crater, while the yellow lineaments are not associated with any crater discussed in this study.

Lutetia was imaged in July 2010 by ESA’s Rosetta spacecraft, while en route to Comet 67P/Churyumov-Gerasimenko. Rosetta took images of the 100 km-wide asteroid for about two hours during the flyby. At its closest approach, Rosetta was 3162 km from Lutetia. In the image shown here, north is up.

Image credit: Besse et al (2014); image: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

Note: For more information, see Lutetia's Dark Side Hosts Hidden Crater.

Thursday, October 9, 2014

Messier 82's Ultraluminous Pulsar


High-energy X-rays streaming from a rare and mighty pulsar (magenta), the brightest found to date, can be seen in this new image combining multi-wavelength data from three telescopes. The bulk of a galaxy called Messier 82 (M82), or the "Cigar galaxy," is seen in visible-light data captured by the National Optical Astronomy Observatory's 2.1-meter telescope at Kitt Peak in Arizona. Starlight is white, and lanes of dust appear brown. Low-energy X-ray data from NASA's Chandra X-ray Observatory are colored blue, and higher-energy X-ray data from NuSTAR are pink.

The magenta object is what's known as an ultraluminous X-ray source, or ULX -- a source of blazing X-rays. Previously, all ULXs were suspected to be massive black holes up to a few hundred times the mass of the sun. But NuSTAR spotted a pulsing of X-rays from this ULX (called M82 X-2) - a telltale sign of a pulsar, not a black hole. A pulsar is a type a neutron star -- a stellar core left over from a supernova explosion -- that sends out rotating beams of high-energy radiation. Scientists were surprised to find the pulsar at the root of the ULX because it shines with a luminosity that is more typical of heftier black holes.

NuSTAR data covers the X-ray energy range of 10 to 40 kiloelectron volts (keV), and Chandra covers the range .1 to 10 keV.


Image credit: NASA/JPL-Caltech/SAO/NOAO

Note: For more information, see:
* M82X-2: Suspected Black Hole Unmasked as Ultraluminous Pulsar
* PIA18840: Galaxy in Different Lights
* PIA18842: Mass Chart for Dead Stars and Black Holes
* PIA18843: NuSTAR Captures the Beat of a Dead Star (Animation)
* PIA18844: Ultraluminous X-ray Sources in M82 Galaxy
* PIA18845: Beacons of X-ray Light (Animation)
* NASA's NuSTAR Telescope Discovers Shockingly Bright Dead Star

Tuesday, October 7, 2014

Comet 67P/Churyumov-Gerasimenko (30 September 2014)


Four-image montage comprising images taken by Rosetta's navigation camera on 30 September from a distance of 18.1 km from the center of Comet 67P/Churyumov-Gerasimenko. Each of the four frames making up the montage measures about 1.4 kilometers across. The image features Site J, the primary landing site for Rosetta’s lander Philae.

Image credit: ESA/Rosetta/NAVCAM

Monday, October 6, 2014

Comet 67P/Churyumov-Gerasimenko's Dimensions


Comet 67P/Churyumov-Gerasimenko's dimensions, as measured from images taken by Rosetta's OSIRIS imaging system. The images shown in the graphic were taken by Rosetta's navigation camera on 19 August.

The larger lobe of the comet measures 4.1 x 3.2 x 1.3 km, while the smaller lobe is 2.5 x 2.5 x 2.0 km.

More details via the blog: Measuring Comet 67P/C-G

Credits: Image: ESA/Rosetta/NAVCAM; Dimensions: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

Sunday, October 5, 2014

Gravity Gradients Frame Oceanus Procellarum


Topography of Earth's moon generated from data collected by the Lunar Orbiter Laser Altimeter, aboard NASA's Lunar Reconnaissance Orbiter, with the gravity anomalies bordering the Procellarum region superimposed in blue. The border structures are shown using gravity gradients calculated with data from NASA's Gravity Recovery and Interior Laboratory (GRAIL) mission. These gravity anomalies are interpreted as ancient lava-flooded rift zones buried beneath the volcanic plains (or maria) on the nearside of the Moon.

Launched as GRAIL A and GRAIL B in September 2011, the probes, renamed Ebb and Flow, operated in a nearly circular orbit near the poles of the moon at an altitude of about 34 miles (55 kilometers) until their mission ended in December 2012. The distance between the twin probes changed slightly as they flew over areas of greater and lesser gravity caused by visible features, such as mountains and craters, and by masses hidden beneath the lunar surface.

The twin spacecraft flew in a nearly circular orbit until the end of the mission on December 17, 2012, when the probes intentionally were sent into the moon's surface. NASA later named the impact site in honor of late astronaut Sally K. Ride, who was America's first woman in space and a member of the GRAIL mission team.

GRAIL's prime and extended science missions generated the highest-resolution gravity field map of any celestial body. The map will provide a better understanding of how Earth and other rocky planets in the solar system formed and evolved.

Image credit: NASA/Colorado School of Mines/MIT/GSFC/Scientific Visualization Studio

Note: For more information, see PIA18821: On the West Coast of the Ocean of Storms (Artist's Concept) and NASA Mission Points to Origin of 'Ocean of Storms' on Earth's Moon.

Saturday, October 4, 2014

Comet 67P/Churyumov-Gerasimenko Jets Firing (26 September 2014)


The four images that make up a new montage of comet 67P/Churyumov-Gerasimenko were taken on September 26, 2014 by the European Space Agency's Rosetta spacecraft. At the time, Rosetta was about 16 miles (26 kilometers) from the center of the comet.

In the montage, a region of jet activity can be seen at the neck of the comet. These jets, originating from several discrete locations, are a product of ices sublimating and gases escaping from inside the nucleus.

The overlapping and slightly dissimilar angles of the four images that compose the montage are a result of the combined effect of the comet rotating between the first and last images taken in the sequence (about 10 degrees over 20 minutes), and the spacecraft movement during that same time.

Launched in March 2004, Rosetta was reactivated in January 2014 after a record 957 days in hibernation. Rosetta is composed of an orbiter and lander. Its objectives since arriving at comet 67P/Churyumov-Gerasimenko earlier this month are to study the celestial object up close in unprecedented detail, prepare for landing a probe on the comet's nucleus in November, and after the landing, track the comet's changes through 2015 as it sweeps past the sun.

Comets are time capsules containing primitive material left over from the epoch when the sun and its planets formed. Rosetta's lander will obtain the first images taken from a comet's surface and will provide comprehensive analysis of the comet's possible primordial composition by drilling into the surface. Rosetta also will be the first spacecraft to witness at close proximity how a comet changes as it is subjected to the increasing intensity of the sun's radiation. Observations will help scientists learn more about the origin and evolution of our solar system and the role comets may have played in seeding Earth with water, and perhaps even life.

Image credit: ESA/Rosetta

Note: For more information, see Rosetta Comet Fires Its Jets.

Friday, October 3, 2014

Comet 67P/Churyumov-Gerasimenko (26 September 2014)


Four-image montage comprising images taken by Rosetta's navigation camera on 26 September from a distance of 26.3 km from Comet 67P/Churyumov-Gerasimenko. The comet nucleus is about 4 km across.

The image shows the spectacular region of activity at the 'neck' of 67P/C-G. This is the product of ices sublimating and gases escaping from inside the comet, carrying streams of dust out into space.

Image credit: ESA/Rosetta/NAVCAM

Titan's South Polar Vortex


These two views of Saturn's moon Titan show the southern polar vortex, a huge, swirling cloud that was first observed by NASA's Cassini spacecraft in 2012.

The view at left is a spectral map of Titan obtained with the Cassini Visual and Infrared Mapping Spectrometer (VIMS) on November 29, 2012. The inset image is a natural-color close-up of the polar vortex taken by Cassini's wide-angle camera (part of the view previously released as PIA14925).

Three distinct components are evident in the VIMS image, represented by different colors: the surface of Titan (orange, near center), atmospheric haze along the limb (light green, at top) and the polar vortex (blue, at lower left).

To the VIMS instrument, the spectrum of the southern polar vortex shows a remarkable difference with respect to other portions of Titan's atmosphere: a signature of frozen hydrogen cyanide molecules (HCN). This discovery has suggested to researchers that the atmosphere of Titan's southern hemisphere is cooling much faster than expected. Observing seasonal shifts like this in the moon's climate is a major goal for Cassini's current extended mission.

Image credit: NASA/JPL-Caltech/ASI/University of Arizona/SSI/Leiden Observatory and SRON

Note: For more information, see Titan's Swirling Polar Cloud is Cold and Toxic (ESA) and Swirling Cloud at Titan's Pole is Cold and Toxic (JPL).

Thursday, October 2, 2014

Messier 11 - The Wild Duck Cluster


The Wide Field Imager (WFI) on the MPG/ESO 2.2-meter telescope at the La Silla Observatory in Chile has taken this beautiful image of the open Wild Duck Cluster, Messier 11, or NGC 6705. The blue stars in the center of the image are the young, hot stars of the cluster. The surrounding redder stars are older, cooler background stars.

Image credit: ESO

Note: For more information, see Wild Ducks Take Flight in Open Cluster.

Tuesday, September 30, 2014

Unusual Changing Feature in Titan's Ligeia Mare


These three images, created from Cassini Synthetic Aperture Radar (SAR) data, show the appearance and evolution of a mysterious feature in Ligeia Mare, one of the largest hydrocarbon seas on Saturn's moon Titan. The views, taken during three different Cassini flybys of Titan, show that this feature was not visible in earlier radar images of the same region and its appearance changed between 2013 and 2014.

In the images, the dark areas represent the sea, which is thought to be composed of mostly methane and ethane. Most of the bright areas represent land surface above or just beneath the water line. The mysterious bright feature appears off the coast below center in the middle and right images.

The mystery feature had not been seen in preceding SAR observations of the region from 2007 to 2009. After its first appearance in early July 2013, it was not visible in observations by Cassini's Visible and Infrared Mapping Spectrometer, obtained later in July and in September 2013. Low-resolution SAR images obtained in October 2013 also failed to recover the feature.

The SAR observation from Cassini's August 21, 2014 Titan flyby shows that the feature was still visible, although its appearance changed during the 11 months since it was last observed. The feature seems to have changed in size between the images from 2013 and 2014 -- doubling from about 30 square miles (about 75 square kilometers) to about 60 square miles (about 160 square kilometers). Ongoing analyses of these data may eliminate some of the explanations previously put forward, or reveal new clues as to what is happening in Titan's seas.

The Cassini radar team is investigating possible origins for the feature, including surface waves, rising bubbles, floating solids, solids that are suspended just below the surface or perhaps something more exotic. Researchers suspect that the appearance of this feature could be related to changing seasons on Titan, as summer draws near in the moon's northern hemisphere. Monitoring such changes is a major goal for Cassini's current extended mission.

The upper half of the middle image uses data from the April 26, 2007 Titan flyby. That area did not receive SAR coverage during the July 10, 2013 encounter, so the earlier data was used to fill-in the scene.

Image credit: NASA/JPL-Caltech/ASI/Cornell

Sunday, September 28, 2014

Landing Site J - Comet 67P/Churyumov-Gerasimenko (21 September 2014)


Rosetta's navigation camera (NAVCAM) took this image of Comet 67P/Churyumov-Gerasimenko on 21 September, from a distance of 27.8 km from the comet center. The image covers an area of about 2 x 1.9 km and focuses on the smaller of the two comet lobes. The primary landing site J is 'above' the distinctive depression in this view. Click here for a context image.

Image credit: ESA/Rosetta/NAVCAM

Note: For more information, see Rosetta to Deploy Lander on 12 November (ESA), Rosetta to Deploy Lander on November 12 (JPL), and Rosetta Mission Status.

Saturday, September 27, 2014

Comet 67P/Churyumov-Gerasimenko (21 September 2014)


Single frame (and cropped) NAVCAM image of Comet 67P/Churyumov-Gerasimenko on 21 September 2014.

Image credit: ESA/Rosetta/NAVCAM

Comet 67P/Churyumov-Gerasimenko (24 September 2014)


Four-image NAVCAM mosaic of Comet 67P/Churyumov-Gerasimenko, using images taken on 24 September 2014 when Rosetta was 28.5 km from the comet.

Image credit: ESA/Rosetta/NAVCAM

Dwarf Galaxy DDO 68


This image from the NASA/ESA Hubble Space Telescope shows a cosmic oddity, dwarf galaxy DDO 68.

This ragged collection of stars and gas clouds looks at first glance like a recently-formed galaxy in our own cosmic neighborhood.

Image credit: ESA/NASA

Note: For more information, see A Galaxy of Deception - Hubble Snaps What Looks Like a Young Galaxy in the Local Universe.