HD 189733: NASA's Chandra Sees Eclipsing Planet in X-rays for First Time

This graphic depicts HD 189733b, the first exoplanet caught passing in front of its parent star in X-rays. As described in our press release, NASA's Chandra X-ray Observatory and the European Space Agency's XMM Newton Observatory have been used to observe a dip in X-ray intensity as HD 189733b transits its parent star.

The main figure is an artist’s impression showing the HD 189733 system, containing a Sun-like star orbited by HD 189733b, an exoplanet about the size of Jupiter. This "hot Jupiter" is over 30 times closer to its star than Earth is to the Sun and goes around the star once every 2.2 days, as determined from previous observations. Also in the illustration is a faint red companion star, which was detected for the first time in X-rays with these observations (roll your mouse over the image above). This star orbits the main star about once every 3,200 years.

The inset contains the Chandra image of HD 189733. The source in the middle is the main star and the source in the lower right is the faint companion star. The source at the bottom of the image is a background object not contained in the HD 189733 system.

The exoplanet itself cannot be seen in the Chandra image, as the transits involve measuring small decreases in X-ray emission from the main star. The authors estimate that the percentage decrease in X-ray light during the transits is about three times greater than the corresponding decrease in optical light. This tells them that the region blocking X-rays from the star is substantially larger than the region blocking optical light from the star, helping to determine the size of the planet's atmosphere. The extended atmosphere implied by these results is shown by the light blue color around the planet. Recent observations of HD 189733b with the Hubble Space Telescope have confirmed that the lower atmosphere of the planet has a deep blue color, due to the preferential scattering of blue light by silicate particles in its atmosphere.

For about a decade astronomers have known that ultraviolet and X-ray radiation from the main star in HD 189733 are evaporating the atmosphere of its closely orbiting planet over time. The authors of the new study estimate that HD 189733b is losing between 100 million and 600 million kilograms per second. This rate is about 25% to 65% higher than it would be if the planet's atmosphere were not extended.

At a distance of just 63 light years, HD 189733b is the closest hot Jupiter to Earth, which makes it a prime target for astronomers who want to learn more about this type of exoplanet and the atmosphere around it.

Chandra was used to make observations of six transits by HD 189733b and the team also used archival data from XMM-Newton for one transit. These results are available online and will appear in a future issue of The Astrophysical Journal.

Illustration credit: X-ray: NASA/CXC/SAO/K.Poppenhaeger et al; Illustration: NASA/CXC/M.Weiss

Note: For more information, see Hubble Spots Azure Blue Planet - True Color of Exoplanet Measured for the First Time and The Strange Attraction of Hot Jupiters.

The Missing Waves of Titan

One of the most shocking discoveries of the past 10 years is how much the landscape of Saturn's moon Titan resembles Earth. Like our own blue planet, the surface of Titan is dotted with lakes and seas; it has river channels, islands, mud, rain clouds and maybe even rainbows. The giant moon is undeniably wet.

The "water" on Titan is not, however, H2O. With a surface temperature dipping 290 degrees F below zero, Titan is far too cold for liquid water. Instead, researchers believe the fluid that sculpts Titan is an unknown mixture of methane, ethane, and other hard-to-freeze hydrocarbons.

The idea that Titan is a wet world with its own alien waters is widely accepted by planetary scientists. Nothing else can account for the observations: NASA's Cassini spacecraft has flown by Titan more than 90 times since 2004, pinging the Moon with radar and mapping its lakes and seas. ESA's Huygens probe parachuted to the surface of Titan in 2005, descending through humid clouds and actually landing in moist soil.

Yet something has been bothering Alex Hayes, a planetary scientist on the Cassini radar team at Cornell University.

If Titan is really so wet, he wonders, "Where are all the waves?"

Here on Earth, bodies of water are rarely still. Breezes blowing across the surface cause waves to ripple and break; raindrops striking sea surfaces also provide some roughness. Yet on Titan, the lakes are eerily smooth, with no discernible wave action down to the millimeter scale, according to radar data from Cassini.

"We know there is wind on Titan," says Hayes. "The moon's magnificent sand dunes [prove] it."

Add to that the low gravity of Titan—only 1/7th that of Earth—which offers so little resistance to wave motion, and you have a real puzzle.

Researchers have toyed with several explanations. Perhaps the lakes are frozen. Hayes thinks that is unlikely, however, "because we see evidence of rainfall and surface temperatures well above the melting point of methane." Or maybe the lakes are covered with a tar-like substance that damps wave motion. "We can't yet rule that out," he adds.

The answer might be found in the results of a study Hayes and colleagues published in the July 2013 online edition of the journal Icarus. Taking into account the gravity of Titan, the low viscosity of liquid hydrocarbons, the density of Titan's atmosphere, and other factors, they calculated how fast wind on Titan would have to blow to stir up waves: A walking-pace breeze of only 1 to 2 mph should do the trick.

This suggests a third possibility: the winds just haven’t been blowing hard enough. Since Cassini reached Saturn in 2004, Titan’s northern hemisphere (where most of the lakes are located) has been locked in the grip of winter. Cold heavy air barely stirs, and seldom reaches the threshold for wave-making.

But now the seasons are changing. In August 2009 the sun crossed Titan’s equator heading north. Summer is coming, bringing light, heat and wind to Titan's lake country.

"According to [climate models], winds will pick up as we approach the solstice in 2017 and should be strong enough for waves," he says.

If waves appear, Cassini should be able to detect them. Radar reflections from wavy lake surfaces can tell researchers a great deal. Wave dimensions, for instance, may reveal the viscosity of the underlying fluid and, thus, its chemical composition. Also, wave speeds would track the speed of the overlying winds, providing an independent check of Titan climate models.

Hayes is excited about "bringing oceanography to another world. All we need now," he says, "are some rough seas."

Video credit: NASA

Comet Ison by Spitzer

These images from NASA's Spitzer Space Telescope of C/2012 S1 (Comet ISON) were taken on June 13, when ISON was 310 million miles (about 500 million kilometers) from the sun. The images were taken with the telescope's infrared array camera at two different near-infrared wavelengths, 3.6 and 4.5 microns (the representational colors shown were selected to enhance visibility). The 3.6-micron image on the left shows a tail of fine rocky dust issuing from the comet and blown back by the pressure of sunlight as the comet speeds towards the sun (the tail points away from the sun). The image on the right side shows the 4.5-micron image with the 3.6-micron image information (dust) removed, and reveals a very different round structure -- the first detection of a neutral gas atmosphere surrounding ISON. In this case, it is most likely created by carbon dioxide that is "fizzing" from the surface of the comet at a rate of about 2.2 million pounds (1 million kilograms) a day.

Comet ISON (officially known as C/2012 S1) is, like all comets, a dirty snowball made up of dust and frozen gases like water, ammonia, methane and carbon dioxide -- some of the fundamental building blocks that scientists believe led to the formation of the planets 4.5 billion years ago. ISON will pass within 724,000 miles (1.2 million kilometers) of the sun on November 28, making it a sungrazer comet that will evaporate its ices and even its rocky dust near perihelion, revealing even more of the comet's composition.

Image credit: NASA/JPL-Caltech/JHUAPL/UCF

Note: For more information, see NASA's Spitzer Observes Gas Emission From Comet ISON.

Comet ISON

In this Hubble Space Telescope composite image taken in April 2013, the sun-approaching Comet ISON floats against a seemingly infinite backdrop of numerous galaxies and a handful of foreground stars. The icy visitor, with its long gossamer tail, appears to be swimming like a tadpole through a deep pond of celestial wonders.

In this composite image, background stars and galaxies were separately photographed in red and yellow-green light. Because the comet moved between exposures relative to the background objects, its appearance was blurred. The blurred comet photo was replaced with a single, black-and-white exposure.

The images were taken with the Wide Field Camera 3 on April 30, 2013.

This photo is one of the original images featured on ISONblog, a new online source offering analysis of Comet ISON by Hubble Space Telescope astronomers and staff at the Space Telescope Science Institute in Baltimore, USA.

Photo credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

The Earth and Moon, by Messenger

The pair of bright star-like features in the upper panel are not stars at all, but the Earth and Moon! MESSENGER was at a distance of 98 million kilometers (61 million miles) from Earth when this picture was taken. The computer-generated image in the lower left shows how the Earth appeared from Mercury at the time. Much of the Americas, all of Europe and Africa, the Middle East, and much of Asia were visible.

MESSENGER took this image as part of a campaign to search for natural satellites of Mercury. Mercury has no moons that we know of. If any exist, they must be small (less than a few kilometers), or we would have seen them by now. The strategy for the satellite search involves taking multiple images of locations at predetermined distances from Mercury, from 2.5 to 25 times the planet radius. Pictures of these points in space are captured at intervals ranging from seconds to nearly an hour, depending on their distances from Mercury. A moving satellite will appear at different positions in images of the same region of space taken at different times.

The Earth and Moon appear very large in this picture because they are overexposed. When looking for potentially dim satellites, long exposures are required to capture as much light as possible. Consequently, bright objects in the field of view become saturated and appear artificially large. In fact, the Earth and Moon are each less than a pixel in size, and no details on either can be seen. The "tails" pointing downward from the Earth and Moon are artifacts caused by the image saturation. These can be seen clearly in the zoomed image in the center lower panel.

This image was taken on the same day that images with Earth in the scene were acquired by the Cassini spacecraft, as part of a mosaic of the backlit Saturn system (http://saturn.jpl.nasa.gov/news/waveatsaturn).

One day later in the search for satellites of Mercury, MESSENGER again took similar images of the Earth and Moon. The date of those images, July 20, was the 44th anniversary of the Apollo 11 landing on the Moon. All six Apollo landing sites are illuminated in the MESSENGER images, although they cannot be resolved. Their locations are marked on the simulated image in the lower right panel.

The background for this image is the region between the constellations Sagittarius (the archer) and Scutum (the shield). The right ascension and declination of Earth are 18h 55m 44s and -18° 25' 31", respectively. Pluto is also in the field of view but far too dim to be seen.

Date Acquired: July 19, 2013, 11:54:41 UTC
Image Mission Elapsed Time (MET): 1016558881
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
WAC Filter: 2 (clear filter)
Field of View: The WAC has a 10.5° field of view

Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

3D View of Carbon Monoxide Emissions in NGC 253

This picture shows a view of a three-dimensional visualization of ALMA observations of cold carbon monoxide gas in the nearby starburst galaxy NGC 253 (The Sculptor Galaxy). The vertical axis shows velocity and the horizontal axis the position across the central part of the galaxy. The colors represent the intensity of the emission detected by ALMA, with pink being the strongest and red the weakest.

These data have been used to show that huge amounts of cool gas are being ejected from the central parts of this galaxy. This will make it more difficult for the next generation of stars to form.

Image credit: ALMA (ESO/NAOJ/NRAO)/Erik Rosolowsky

Note: For more information, see Starburst to Star Bust.

All-Sky Map of the Third XMM-Newton Serendipitous Source Catalog (3XMM-DR4)

This image shows the density of observed objects in the third XMM-Newton Serendipitous Source Catalogue (3XMM-DR4), mapped in Galactic coordinates.

Sources in the 3XMM catalog are identified and isolated from serendipitous data recorded by XMM-Newton's EPIC X-ray cameras. In each of the 600-700 observations made each year, around 70 extra sources are captured in addition to the target object which usually only takes up a small fraction of the field of view. Covering observations between February 2000 and December 2012, the 3XMM catalog contains some 531,261 X-ray source detections relating to 372,728 unique X-ray sources.

The inset shows an expanded view of the small region indicated where the individual sources can be seen.

Image credit: ESA/XMM-Newton/EPIC/M. Watson (University of Leicester)

Note: For more information, see Latest XMM-Newton Catalogue Offers New X-Ray Vision.

The Earth, by Cassini

In this rare image taken on July 19, 2013, the wide-angle camera on NASA's Cassini spacecraft has captured Saturn's rings and our planet Earth and its moon in the same frame. It is only one footprint in a mosaic of 33 footprints covering the entire Saturn ring system (including Saturn itself). At each footprint, images were taken in different spectral filters for a total of 323 images: some were taken for scientific purposes and some to produce a natural color mosaic. This is the only wide-angle footprint that has the Earth-moon system in it.

The dark side of Saturn, its bright limb, the main rings, the F ring, and the G and E rings are clearly seen; the limb of Saturn and the F ring are overexposed. The "breaks" in the brightness of Saturn's limb are due to the shadows of the rings on the globe of Saturn, preventing sunlight from shining through the atmosphere in those regions. The E and G rings have been brightened for better visibility.

Earth, which is 898 million miles (1.44 billion kilometers) away in this image, appears as a blue dot at center right; the moon can be seen as a fainter protrusion off its right side. An arrow indicates their location in the annotated version. (The two are clearly seen as separate objects in the accompanying narrow angle frame: PIA14949.) The other bright dots nearby are stars.

This is only the third time ever that Earth has been imaged from the outer solar system. The acquisition of this image, along with the accompanying composite narrow- and wide-angle image of Earth and the moon and the full mosaic from which both are taken, marked the first time that inhabitants of Earth knew in advance that their planet was being imaged. That opportunity allowed people around the world to join together in social events to celebrate the occasion.

This view looks toward the unilluminated side of the rings from about 20 degrees below the ring plane.

Images taken using red, green and blue spectral filters were combined to create this natural color view. The images were obtained with the Cassini spacecraft wide-angle camera on July 19, 2013 at a distance of approximately 753,000 miles (1.212 million kilometers) from Saturn, and approximately 898.414 million miles (1.445858 billion kilometers) from Earth. Image scale on Saturn is 43 miles (69 kilometers) per pixel; image scale on the Earth is 53,820 miles (86,620 kilometers) per pixel. The illuminated areas of neither Earth nor the Moon are resolved here. Consequently, the size of each "dot" is the same size that a point of light of comparable brightness would have in the wide-angle camera.

Photo credit: NASA/JPL-Caltech/Space Science Institute

Note: For more information, see NASA Releases Images of Earth by Distant Spacecraft, PIA17170: One Special Day in the Life of Planet Earth -- Close-Up (which clearly shows the Earth and Moon as two separate objects), PIA17038: Two Views of Home (which shows the Earth taken by both Cassini, around Saturn, and Messenger, around Mercury, on the same day), PIA14949: One Special Day in the Life of Planet Earth, Cassini’s Pale Blue Dot and Pale Blue Dot: Distant Spacecraft Photograph Earth.

IBEX Maps the Sun's Heliotail

Like a comet, the solar system has a tail. NASA's Interstellar Boundary Explorer (IBEX) has for the first time mapped out the structure of this tail, which is shaped like a four-leaf clover.

Scientists describe the tail, called the heliotail, based on the first three years of IBEX imagery in a paper published in the July 10 edition of the Astrophysical Journal.

While telescopes have spotted such tails around other stars, it has been difficult to see whether our star produced one. The particles found in the tail -- and throughout the entire heliosphere, the region of space influenced by our sun -- do not shine, so they cannot be seen with conventional instruments.

"By examining the neutral atoms, IBEX has made the first observations of the heliotail," said David McComas, IBEX principal investigator at Southwest Research Institute in San Antonio, Texas, and the paper's lead author. "Many models have suggested the heliotail might look like this or like that, but we have had no observations. We always drew pictures where the tail of the solar system just trailed off the page, since we couldn't even speculate about what it really looked like."

Other stars show tails that trail behind them like a comet’s tail; [pictured above is the star Mira and its tail, shown in ultraviolet light and imaged by the GALEX satellite]. Scientists used NASA’s Interstellar Boundary Explorer to confirm that our solar system has one too.

IBEX measures the neutral particles created by collisions at the solar system's boundaries. This technique, called energetic neutral atom imaging, relies on the fact that the paths of neutral particles are not affected by the solar magnetic field. Instead, the particles travel in a straight line from collision to IBEX. Consequently, observing where the neutral particles came from describes what is going on in these distant regions.

"Since first light in 2008, the IBEX mission team has amazed us with its discoveries at the interstellar boundary, including a previously unknown ribbon of energetic neutral particles stretching across it," said Arik Posner, NASA's IBEX program scientist in Washington. "The new IBEX image of the heliotail fills in a previously blank area on the map. We are first-hand witnesses of rapid progress in heliophysics science."

By combining observations from the first three years of IBEX imagery, the team showed a tail with a combination of fast and slow moving particles. There are two lobes of slower particles on the sides and faster particles above and below. This four-leaf clover shape can be attributed to the fact that the sun has been sending out fast solar wind near its poles and slower wind near its equator for the last few years. This is a common pattern in the most recent phase of the sun's 11-year activity cycle.

The clover shape does not align perfectly with the solar system, however. The entire shape is rotated slightly, indicating that as it moves further away from the sun and its magnetic influence, the charged particles begin to be nudged into a new orientation, aligning with the magnetic fields from the local galaxy.

Scientists do not know how long the tail is, but think that it eventually fades away and becomes indistinguishable from the rest of interstellar space. Scientists are testing their current computer simulations of the solar system against the new observations to improve our understanding of the comet-like tail streaming out behind us.

Video credit: NASA; image credit: NASA/JPL-Caltech/GALEX

NGC 4866

The constellation of Virgo (The Virgin) is the largest of the Zodiac constellations, and the second largest overall after Hydra (The Water Snake). Its most appealing feature, however, is the sheer number of galaxies that lie within it. In this picture, among a crowd of face- and edge-on spiral, elliptical, and irregular galaxies, lies NGC 4866, a lenticular galaxy situated about 80 million light-years from Earth. This sharp image of NGC 4866 was captured by the Advanced Camera for Surveys, an instrument on the NASA/ESA Hubble Space Telescope.

Photo credit: ESA/Hubble & NASA; Acknowledgement: Gilles Chapdelaine

The Moon by LRO

Video credit: NASA/GSFC/Arizona State University

Note: For more information, see A Unique View of the Moon.

Snow Rings Around TW Hydrae

An artist's concept of the snow line in TW Hydrae showing water ice covered dust grains in the inner disc (4.5–30 astronomical units, blue) and carbon monoxide ice covered grains in the outer disc (>30 astronomical units, green). The transition from blue to green marks the carbon monoxide snow line. The snow helps grains of dust to adhere to each other by providing a sticky coating, which is essential to the formation of planets and comets. Due to the different freezing points of different chemical compounds, different snow lines can be found at various distances from the star.

This ALMA image shows the region where carbon monoxide snow has formed around the star. The carbon monoxide is shown here in green, and begins at a distance of more than 30 astronomical units from TW Hydrae. Aside from being necessary for planetary and comet formation, carbon monoxide is needed for the creation of methanol which is a fundamental building block required for life.

Credit: (top) B. Saxton & A. Angelich/NRAO/AUI/NSF/ALMA (ESO/NAOJ/NRAO); (bottom) ALMA (ESO/NAOJ/NRAO)

Note: For more information, see Snow in an Infant Planetary System.

Gas Cloud Ripped Apart by the Milky Way's Central Black Hole

New observations from ESO’s Very Large Telescope show how a gas cloud now passing close to the supermassive black hole at the center of the galaxy is being ripped apart. The horizontal axis shows the extent of the cloud along its orbit and the vertical axis shows the velocities of different parts of the cloud. The cloud is now dramatically stretched out and the velocity of the front is several million km/h different from that of the tail.

Image credit: ESO/S. Gillessen

Note: For more information, see Ripped Apart by a Black Hole.

Exoplanet HD 189733b

This artist's concept shows exoplanet HD 189733b orbiting its yellow-orange star, HD 189733. NASA's Hubble Space Telescope measured the actual visible-light color of the planet, which is deep blue.

Astronomers working with NASA's Hubble Space Telescope have deduced the actual color of a planet orbiting another star 63 light-years away.

The planet is HD 189733b, one of the closest exoplanets that can be seen crossing the face of its star, and its color is cobalt blue. If seen directly, this planet would look like a deep blue dot, reminiscent of Earth's color as seen from space.

Hubble's Space Telescope Imaging Spectrograph measured changes in the color of light from the planet before, during and after a pass behind its star. There was a small drop in light and a slight change in the color of the light. "We saw the light becoming less bright in the blue but not in the green or red. Light was missing in the blue but not in the red when it was hidden," said research team member Frederic Pont of the University of Exeter in South West England. "This means that the object that disappeared was blue."

Earlier observations have reported evidence for scattering of blue light on the planet. The latest Hubble observation confirms the evidence.

Although the planet resembles Earth in terms of color, it is not an Earth-like world.

On this turbulent alien world, the daytime temperature is nearly 2,000 degrees Fahrenheit, and it possibly rains glass -- sideways -- in howling, 4,500-mph winds. The cobalt blue color comes not from the reflection of a tropical ocean as it does on Earth, but rather a hazy, blow-torched atmosphere containing high clouds laced with silicate particles. Silicates condensing in the heat could form very small drops of glass that scatter blue light more than red light.

This plot compares the colors of planets in our solar system to exoplanet HD 189733b. The exoplanet's deep blue color is produced by silicate droplets, which scatter blue light in its atmosphere.

Hubble and other observatories have made intensive studies of HD 189733b and found its atmosphere to be changeable and exotic.

HD 189733b is among a bizarre class of planets called hot Jupiters, which orbit precariously close to their parent stars.

HD 189733b was discovered in 2005. It is only 2.9 million miles from its parent star, so close that it is gravitationally locked. One side always faces the star and the other side is always dark.

In 2007, NASA's Spitzer Space Telescope measured the infrared light, or heat, from the planet, leading to one of the first temperature maps for an exoplanet. The map shows day side and night side temperatures on HD 189733b differ by about 500 degrees Fahrenheit. This should cause fierce winds to roar from the day side to the night side.

Image credits: (top) NASA, ESA, and G. Bacon (STScI); (bottom) NASA, ESA, and A. Feild (STScI)

Neptune's New Moon, S/2004 N1

NASA's Hubble Space Telescope has discovered a new moon orbiting the distant blue-green planet Neptune, the 14th known to be circling the giant planet.

The moon, designated S/2004 N 1, is estimated to be no more than 12 miles across, making it the smallest known moon in the Neptunian system. It is so small and dim that it is roughly 100 million times fainter than the faintest star that can be seen with the naked eye. It even escaped detection by NASA's Voyager 2 spacecraft, which flew past Neptune in 1989 and surveyed the planet's system of moons and rings.

Mark Showalter of the SETI Institute in Mountain View, California, found the moon July 1, while studying the faint arcs, or segments of rings, around Neptune. "The moons and arcs orbit very quickly, so we had to devise a way to follow their motion in order to bring out the details of the system," he said. "It's the same reason a sports photographer tracks a running athlete -- the athlete stays in focus, but the background blurs."

The method involved tracking the movement of a white dot that appears over and over again in more than 150 archival Neptune photographs taken by Hubble from 2004 to 2009.

On a whim, Showalter looked far beyond the ring segments and noticed the white dot about 65,400 miles from Neptune, located between the orbits of the Neptunian moons Larissa and Proteus. The dot is S/2004 N 1. Showalter plotted a circular orbit for the moon, which completes one revolution around Neptune every 23 hours.

For images, video, and more information Neptune's new moon, visit: http://hubblesite.org/news/2013/30

Image credit: NASA, ESA, M. Showalter/SETI Institute

NGC 6744

This image from NASA's Galaxy Evolution Explorer shows NGC 6744, one of the galaxies most similar to our Milky Way in the local universe. This ultraviolet view highlights the vast extent of the fluffy spiral arms, and demonstrates that star formation can occur in the outer regions of galaxies.

The galaxy is situated in the constellation of Pavo at a distance of about 30 million light-years.

NGC 6744 is bigger than the Milky Way, with a disk stretching 175,000 light-years across. A small, distorted companion galaxy is located nearby, which is similar to our galaxy's Large Magellanic Cloud. This companion, called NGC 6744A, can be seen as a blob in the main galaxy's outer arm, at upper right.

On June 28, 2013, NASA turned off its Galaxy Evolution Explorer (GALEX) after a decade of operations in which the venerable space telescope used its ultraviolet vision to study hundreds of millions of galaxies across 10 billion years of cosmic time.

Highlights from the mission's decade of sky scans include:

-- Discovering a gargantuan, comet-like tail behind a speeding star called Mira.
-- Catching a black hole "red-handed" as it munched on a star.
-- Finding giant rings of new stars around old, dead galaxies.
-- Independently confirming the nature of dark energy.
-- Discovering a missing link in galaxy evolution -- the teenage galaxies transitioning from young to old.

The mission also captured a dazzling collection of snapshots, showing everything from ghostly nebulas to a spiral galaxy with huge, spidery arms.

Image credit: NASA/JPL-Caltech

Luca Parmitano Self-Portrait

These images were taken by ESA astronaut Luca Parmitano during his spacewalk, together with NASA's Chris Cassidy, 9 July 2013.

The spacewalk, the first for Luca and the fifth for Chris, lasted 6 hours 7 minutes.

This was the first of two Expedition 36 excursions to prepare the International Space Station for a new Russian module and perform additional installations on the station’s backbone.

The second spacewalk is scheduled for 16 July; Luca, working again with Chris Cassidy, will egress the Quest airlock at around 12:15 GMT (14:15 CEST).

Photo credit: ESA/NASA

NGC 3185

This is the spiral galaxy NGC 3185, located some 80 million light-years away from us in the constellation of Leo (the Lion). The image shows the galaxy’s spiral arms, which can be traced from the center of the galaxy out towards the rim, where they appear to meet a sparkling blue disk.

At the center of NGC 3185 is a small but very bright nucleus containing a supermassive black hole. Black holes like this one can have masses many thousands of times that of the sun, and they become active when matter falls towards them. When this happens the black hole lights up, sending away streams of particles and radiation at almost the speed of light.

NGC 3185 is a member of a small, four-galaxy group called Hickson 44, which has a celebrity in its midst — the group is also home to another spiral galaxy called NGC 3190. NGC 3190 may be very familiar to you: the technology giant Apple Inc. used a blue-tinted image of it as a desktop image for one of its operating systems.

Photo credit: European Space Agency/NASA/Hubble

NGC 2392

Stars like the Sun can become remarkably photogenic at the end of their life. A good example is NGC 2392, which is located about 4,200 light years from Earth. NGC 2392, (nicknamed the "Eskimo Nebula") is what astronomers call a planetary nebula. This designation, however, is deceiving because planetary nebulas actually have nothing to do with planets. The term is simply a historic relic since these objects looked like planetary disks to astronomers in earlier times looking through small optical telescopes.

Instead, planetary nebulas form when a star uses up all of the hydrogen in its core -- an event our Sun will go through in about five billion years. When this happens, the star begins to cool and expand, increasing its radius by tens to hundreds of times its original size. Eventually, the outer layers of the star are carried away by a 50,000 kilometer per hour wind, leaving behind a hot core. This hot core has a surface temperature of about 50,000 degrees Celsius, and is ejecting its outer layers in a much faster wind traveling six million kilometers per hour. The radiation from the hot star and the interaction of its fast wind with the slower wind creates the complex and filamentary shell of a planetary nebula. Eventually the remnant star will collapse to form a white dwarf star.

Now days, astronomers using space-based telescopes are able to observe planetary nebulas such as NGC 2392 in ways their scientific ancestors probably could never imagine. This composite image of NGC 2392 contains X-ray data from NASA's Chandra X-ray Observatory in purple showing the location of million-degree gas near the center of the planetary nebula. Data from the Hubble Space Telescope show — colored red, green, and blue — the intricate pattern of the outer layers of the star that have been ejected. The comet-shaped filaments form when the faster wind and radiation from the central star interact with cooler shells of dust and gas that were already ejected by the star.

The observations of NGC 2392 were part of a study of three planetary nebulas with hot gas in their center. The Chandra data show that NGC 2392 has unusually high levels of X-ray emission compared to the other two. This leads researchers to deduce that there is an unseen companion to the hot central star in NGC 2392. The interaction between a pair of binary stars could explain the elevated X-ray emission found there. Meanwhile, the fainter X-ray emission observed in the two other planetary nebulas in the sample — IC 418 and NGC 6826 — is likely produced by shock fronts (like sonic booms) in the wind from the central star. A composite image of NGC 6826 was included in a gallery of planetary nebulas released in 2012.

Image credit: X-ray: NASA/CXC/IAA-CSIC/N.Ruiz et al, Optical: NASA/STScI

Protostar in Dark Cloud SDC 335.579-0.292

Observations of the dark cloud SDC 335.579-0.292 using the Atacama Large Millimeter/submillimeter array (ALMA) have given astronomers the best view yet of a monster star in the process of forming. A stellar womb with over 500 times the mass than the Sun has been found and appears as the yellow blob near the center of this picture. This is the largest ever seen in the Milky Way — and it is still growing. The embryonic star within is hungrily feeding on the material that is racing inwards. It is expected to give birth to a very brilliant star with up to 100 times the mass of the Sun.

This image combines data from ALMA and NASA’s Spitzer Space Telescope.

Image credit: ALMA (ESO/NRAJ/NRAO)/NASA/Spitzer/JPL-Caltech/GLIMPSE

Note: For more information, see ALMA Prenatal Scan Reveals Embryonic Monster Star.

Two Views of Olympus Mons' Southeast Flank

A portion of the southeastern flank of Olympus Mons as imaged by the High Resolution Stereo Camera on ESA’s Mars Express on 21 January 2013 (orbit 11524), with a ground resolution of approximately 17 m per pixel. The image center is located at approximately 14°N / 229°E. North is to the right.

The image highlights the stark contrast between the hundreds of narrow, individual lava flows on the flanks of the volcano, and the smooth lava plains that surround it.

Color-coded topographical map of the southeastern flank of the Olympus Mons volcano on Mars. The transitions from the sloping flanks of the volcano (white, red and yellow colors) to the steep cliff faces (green to light blue) and the smooth plains at its base (dark blue) can clearly be seen.

The image was taken by the High Resolution Stereo Camera on ESA’s Mars Express on 21 January 2013 (orbit 11524), with a ground resolution of approximately 17 m per pixel. The image center is located at approximately 14°N / 229°E.

Image credits: (Top) ESA/DLR/FU Berlin (G. Neukum); (Bottom) ESA/DLR/FU Berlin (G. Neukum).

Artist’s Impression of a Galaxy Accreting Material from its Surroundings

This artist’s impression shows a galaxy in the distant Universe, just two billion years after the Big Bang, in the process of pulling in cool gas (shown in orange) from its surroundings. Astronomers have been able to find out a lot about this object by studying not just the galaxy, but also the light of a much more distant quasar (the bright object to the left of the central galaxy), which happens to be in the right place to shine through the accreting gas. The motions of the gas and its composition fit very well with theories of cool gas accretion as a way of feeding star formation and galaxy growth.

Illustration credit: ESO/L. Calçada/ESA/AOES Medialab

Note: For more information, see Feeding Galaxy Caught in Distant Searchlight.

Kerberos and Styx

From the USGS Astrogeology Science Center:

The IAU has approved the names Kerberos for Pluto's moon formerly known as P4, and Styx for Pluto's moon formerly known as P5. For detailed information about this naming, see the IAU press release. For more information about Kerberos and Styx and other moons and planets in our Solar System, see the Planet and Satellite Names and Discoverers page in the Gazetteer of Planetary Nomenclature.