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.


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)

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.

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.

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.


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).

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

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

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.

Thursday, September 25, 2014

Clear Skies on HAT-P-11b

A Neptune-size planet with a clear atmosphere is shown crossing in front of its star in this artist's depiction. Such crossings, or transits, are observed by telescopes like NASA's Hubble and Spitzer to glean information about planets' atmospheres. As starlight passes through a planet's atmosphere, atoms and molecules absorb light at certain wavelengths, blocking it from the telescope's view. The more light a planet blocks, the larger the planet appears. By analyzing the amount of light blocked by the planet at different wavelengths, researchers can determine which molecules make up the atmosphere.

The problem with this technique is that sometimes planets have thick clouds that block any light from coming through, hiding the signature of the molecules in the atmosphere. This is particularly true of the handful of Neptune-size and super-Earth planets examined to date, all of which appear to be cloudy.

As a result, astronomers were elated to find clear skies on a Neptune-size planet called HAT-P-11b, as illustrated here. Without clouds to block their view, they were able to identify water vapor molecules in the planet's atmosphere. The blue rim of the planet in this image is due to scattered light, while the orange rim on the part of the planet in front of the star indicates the region where water vapor was detected.

Image credit: NASA/JPL-Caltech

Note: For more information, see PIA18838: A Sunny Outlook for 'Weather' on Exoplanets (Artist's Concept), PIA18839: Transmission Spectrum of HAT-P-11b, NASA Telescopes Find Clear Skies and Water Vapor on Exoplanet, and Clear Skies on Exo-Neptune - Smallest Exoplanet Ever Found to Have Water Vapor.

Tuesday, September 23, 2014

Saturn's North Polar Hexagon

The giant planet Saturn is mostly a gigantic ball of rotating gas, completely unlike our solid home planet. But Earth and Saturn do have something in common: weather, although the gas giant is home to some of the most bizarre weather in our Solar System, such as the swirling storm shown in this Cassini view.

Known as “the hexagon”, this weather feature is an intense, six-sided jet stream at Saturn’s north pole. Spanning some 30,000 km across, it hosts howling 320 km/h winds that spiral around a massive storm rotating anticlockwise at the heart of the region.

Numerous small vortices rotate in the opposite direction to the central storm and are dragged around with the jet stream, creating a terrifically turbulent region. While a hurricane on Earth may last a week or more, the hexagon has been raging for decades, and shows no signs of letting up.

This false-color image of the hexagon was made using ultraviolet, visible and infrared filters to highlight different regions.

The dark center of the image shows the large central storm and its eye, which is up to 50 times bigger than a terrestrial hurricane eye. The small vortices show up as pink-red clumps. Towards the lower right of the frame is a white-tinted oval storm that is bigger than any of the others — this is the largest of the vortices at some 3500 km across, twice the size of the largest hurricane ever recorded on Earth.

The darker blue region within the hexagon is filled with small haze particles, whereas the paler blue region is dominated by larger particles. This divide is caused by the hexagonal jet stream acting as a shepherding barrier — large particles cannot enter the hexagon from the outside.

These large particles are created when sunlight shines onto Saturn’s atmosphere, something that only started relatively recently in the northern hemisphere with the beginning of northern spring in August 2009.

Cassini will continue to track changes in the hexagon, monitoring its contents, shape and behavior as summer reaches Saturn’s northern hemisphere in 2017.

An animated version is available here.

Image credit: NASA/JPL-Caltech/SSI/Hampton University

Monday, September 22, 2014

Hooke Crater and Argyre Planitia

Color-coded topography map of a region of the Argyre basin, featuring Hooke crater and part of the floor of the basin known as Argyre Planitia. White and red show the highest terrains, while blue and purple show the deepest. The image is based on a digital terrain model of the region, from which the topography of the landscape can be derived. The region clearly slopes to the south (left).

The image was acquired by the High Resolution Stereo Camera on Mars Express on 20 April 2014 during orbit 13,082. The ground resolution is about 63 m per pixel. Hooke crater is located at about 46°S / 316°E. North is right and East is down.

Image credit: ESA/DLR/FU Berlin

Sunday, September 21, 2014

Dwarf Galaxy M60-UDC1

This NASA/ESA Hubble Space Telescope image shows the dwarf galaxy M60-UDC1. Lying about 50 million light-years away, M60-UCD1 is a tiny galaxy with a diameter of 300 light-years – just 1/500th of the diameter of the Milky Way! Despite its size it is pretty crowded, containing some 140 million stars.

The dwarf galaxy may actually be the stripped remnant of a larger galaxy that was torn apart during a close encounter with its neighbor, a massive galaxy called Messier 60.

Circumstantial evidence for this comes from the recent discovery of a monster black hole, which is not visible in this image, at the center of the dwarf. The black hole makes up 15 percent of the mass of the entire galaxy, making it much too big to have formed inside a dwarf galaxy.

Image credit: NASA, ESA and A. Seth (University of Utah, USA)

Note: For more information, see Big Surprises Can Come in Small Packages - Hubble Helps Astronomers Find Smallest Known Galaxy With Supermassive Black Hole.

Saturday, September 20, 2014

Comet 67P/Churyumov-Gerasimenko (19 September 2014)

Four-image NAVCAM mosaic of Comet 67P/Churyumov-Gerasimenko, using images taken on 19 September 2014 when Rosetta was 28.6 km from the comet.

Image credit: ESA/Rosetta/NAVCAM

NGC 6872 and IC 4970

This picture, taken by the NASA/ESA Hubble Space Telescope’s Wide Field Planetary Camera 2 (WFPC2), shows a galaxy known as NGC 6872 in the constellation of Pavo (The Peacock). Its unusual shape is caused by its interactions with the smaller galaxy that can be seen just above NGC 6872, called IC 4970. They both lie roughly 300 million light-years away from Earth.

From tip to tip, NGC 6872 measures over 500,000 light-years across, making it the second largest spiral galaxy discovered to date. In terms of size it is beaten only by NGC 262, a galaxy that measures a mind-boggling 1.3 million light-years in diameter! To put that into perspective, our own galaxy, the Milky Way, measures between 100,000 and 120,000 light-years across, making NGC 6872 about five times its size.

The upper left spiral arm of NGC 6872 is visibly distorted and is populated by star-forming regions, which appear blue on this image. This may have been be caused by IC 4970 recently passing through this arm — although here, recent means 130 million years ago! Astronomers have noted that NGC 6872 seems to be relatively sparse in terms of free hydrogen, which is the basis material for new stars, meaning that if it weren’t for its interactions with IC 4970, NGC 6872 might not have been able to produce new bursts of star formation.

Image credit: ESA/Hubble & NASA

Note: For more information, see PIA17808: Hubble Feathers the Peacock.

Friday, September 19, 2014

Artist's Conception of WASP-18b

WASP-18: An exoplanet about ten times Jupiter’s mass located some 330 light years from Earth.

The artist's illustration featured in the main part of this graphic depicts a star and its planet, WASP-18b, a giant exoplanet that orbits very close to it. A new study using Chandra data has shown that WASP-18b is making the star that it orbits act much older than it actually is. The lower inset box reveals that no X-rays were detected during a long Chandra observation. This is surprising given the age of the star, suggesting the planet is weakening the star’s magnetic field through tidal forces.

Scale: Inset image is about 5.3 arcmin across (about 0.5 light years).

Image credit: X-ray: NASA/CXC/SAO/I.Pillitteri et al; Optical: DSS; Illustration: NASA/CXC/M.Weiss

Note: For more information, see WASP-18: NASA's Chandra X-ray Observatory Finds Planet That Makes Star Act Deceptively Old.

Thursday, September 18, 2014

Distribution of Molecular Gas in 30 Merging Galaxies

Each of the colorful objects in this image illustrates one of 30 merging galaxies. The contours in the individual galaxies show the signal strength from carbon monoxide while the color represents the motion of gas. Gas that is moving away from us appears red while the blue color shows gas that is approaching. The contours together with the transition from red to blue indicate a gaseous disc that is rotating about the center of the galaxy.

Image credit: ALMA (ESO/NAOJ/NRAO)/SMA/CARMA/IRAM/J. Ueda et al.

Note: For more information, see Violent Origins of Disc Galaxies Probed by ALMA.

Wednesday, September 17, 2014

Pulsar PSR J1640-4631

The blue dot in this image marks the spot of an energetic pulsar -- the magnetic, spinning core of star that blew up in a supernova explosion. NASA's Nuclear Spectroscopic Telescope Array, or NuSTAR, discovered the pulsar by identifying its telltale pulse -- a rotating beam of X-rays, that like a cosmic lighthouse, intersects Earth every 0.2 seconds.

The pulsar, called PSR J1640-4631, lies in our inner Milky Way galaxy about 42,000 light-years away. It was originally identified by as an intense source of gamma rays by the High Energy Stereoscopic System (H.E.S.S.) in Namibia. NuSTAR helped pin down the source of the gamma rays to a pulsar.

The other pink dots in this picture show low-energy X-rays detected by NASA's Chandra X-ray Observatory.

In this image, NuSTAR data is blue and shows high-energy X-rays with 3 to 79 kiloelectron volts; Chandra data is pink and shows X-rays with 0.5 to 10 kiloeletron volts.

Image credit: NASA/JPL-Caltech/SAO

Note: For more information, see Pulse of a Dead Star Powers Intense Gamma Rays.

Tuesday, September 16, 2014

Philae Secondary Landing Site - Site C

Site C was chosen as the backup site for Rosetta’s lander Philae during the Landing Site Selection Group meeting held on 13–14 September 2014.

The image was taken by Rosetta's narrow-angle camera from a distance of about 70 km. The resolution is 1.5 meters/pixel.

Full story: 'J' marks the spot for Rosetta's lander


Note: For more information, see 'J' Marks the Spot for Rosetta's Lander.

Philae's Primary Landing Site - Site J

Philae’s primary landing site will target Site J, the center of which is indicated by the cross in this OSIRIS narrow-angle image.

Site J is located on the head of Comet 67P/Churyumov–Gerasimenko and is close to the candidate site B, the large depression to the right of the image.

Site J offers the minimum risk to the lander in comparison to the other candidate sites, and is also scientifically interesting, with signs of activity nearby. At Site J, the majority of slopes are less than 30º relative to the local vertical, reducing the chances of Philae toppling over during touchdown. Site J also appears to have relatively few boulders and receives sufficient daily illumination to recharge Philae and continue science operations on the surface beyond the initial battery-powered phase.

Full story: 'J' marks the spot for Rosetta's lander


Note: For more information, see:
* Philae’s Primary Landing Site Close-Up
* Philae’s Primary Landing Site in Context
* Philae’s Primary Landing Site in 3D
* 'J' Marks the Spot for Rosetta's Lander (ESA Science)
* PIA18809: Rosetta Lander's Primary Landing Site
* PIA18810: Rosetta Lander's Backup Landing Site
* 'J' Marks the Spot for Rosetta's Lander (JPL)
* Announcement of the Selected Rosetta Primary Landing Site and a Backup
* Replay: Rosetta Landing Site Announcement (Video)

For more information about Philae and the mission, see:
* Philae's Panoramic Camera
* Philae’s Descent and Science on the Surface
* How to Orbit a Comet (all of the above are videos)
* Rosetta and Philae at Comet

Monday, September 15, 2014

Supernova Gaia14aaa and Its Host Galaxy

This image shows the supernova named Gaia14aaa as seen on 10 September 2014 with the robotic Liverpool Telescope on La Palma, in the Canary Islands, Spain. This is a Type Ia supernova – the explosion of a white dwarf locked in a binary system with a companion star – and it was discovered in the data collected with ESA’s Gaia satellite on 30 August.

In the left panel, the image from the Liverpool Telescope shows both Gaia14aaa and its host galaxy, named SDSS J132102.26+453223.8, which is about 500 million light-years away. In this image, the supernova is slightly offset from the galaxy’s core.

The central panel shows an image of the same galaxy, taken as part of the Sloan Digital Sky Survey, several years before the explosion of Gaia14aaa could be observed from Earth.

The right panel was obtained by subtracting the second image, which contains the light emitted by the galaxy, from the first one, which depicts both the galaxy and the supernova. The difference between the two images clearly shows the appearance of Gaia14aaa.

Image credit: M. Fraser/S. Hodgkin/L. Wyrzykowski/H. Campbell/N. Blagorodnova/Z. Kostrzewa-Rutkowska/Liverpool Telescope/SDSS

Note: For more information, see Gaia Discovers Its First Supernova.

Sunday, September 14, 2014

Comet 67P/Churyumov-Gerasimenko (11 August 2014) From Earth

Since early August 2014, Rosetta has been enjoying a close-up view of comet 67P/Churyumov–Gerasimenko. Meanwhile, astronomers on Earth have been busy following the comet with ground-based telescopes. As Rosetta is deep inside the ‘atmosphere’ coma – it was 100 km from the nucleus on 6 August, and has been getting much closer since then – the only way to view the whole comet is to ‘stand back’ and observe it from Earth.

This image was recorded on 11 August 2014 using one of the 8 m-diameter telescopes of the European Southern Observatory’s Very Large Telescope in Chile.

Although faint, the comet is clearly active, revealing a dusty coma extending at least 19,000 km from the nucleus. The comet's dusty veil is not symmetrical as the dust is swept away from the Sun – located beyond the lower-right corner of the image – to begin forming a tail.

At the moment, the comet is visible only from the southern hemisphere and, at more than 500 million km from the Sun, it is still very faint. In addition, it currently sits in a patch of the sky where it is camouflaged against the crowded starry background of the Milky Way. For these reasons, the image was compiled by superimposing 40 individual exposures, each lasting about 50 seconds, and removing background stars.

A large collaboration of astronomers across the world has been working to make the most of the unique opportunity to observe the comet from the ground while Rosetta is performing measurements at the comet. The Very Large Telescope is taking images every two nights on average. These short exposures monitor the comet’s activity by studying how its brightness changes. The results are used by the Rosetta team to help plan spacecraft operations.

Image credit: C. Snodgrass/ESO/ESA

Saturday, September 13, 2014

Comet 67P/Churyumov-Gerasimenko (10 September 2014)

Four image NAVCAM mosaic of Comet 67P/Churyumov-Gerasimenko, using images taken on 10 September when Rosetta was 27.8 km from the comet.

Image credit: ESA/Rosetta/NAVCAM

SNR Puppis A

Puppis A: A supernova remnant located about 7,000 light years from Earth.

The destructive results of a powerful supernova explosion are seen in a delicate tapestry of X-ray light in this new image. The remnant is called Puppis A, which could have been witnessed on Earth about 3,700 years ago and is about 10 light years across. This image is the most complete and detailed X-ray view of Puppis A ever obtained, made by combining a mosaic of different Chandra and XMM-Newton observations. In this image, low-energy X-rays are shown in red, medium-energy X-rays are in green and high energy X-rays are colored blue.

Scale: Image is about 1.5 degrees across (About 180 light years).

Image credit: X-ray: NASA/CXC/IAFE/G.Dubner et al & ESA/XMM-Newton

Note: For more information, see Puppis A: An X-Ray Tapestry.