Vesta's South Polar Scarp

NASA's Dawn spacecraft obtained this image with its framing camera on August 12, 2011. The image was taken through the framing camera's clear filter. The image has a resolution of about 260 meters per pixel.

Photo credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Note: The Minister is not sure of the height of this particular escarpment. At its highest point, he comes up with a measurement of 145 pixels (more or less). However, this cannot surely be! 145 pixels x 260 meters per pixel = 37,700 meters! A cliff 37 km tall? Even Verona Rupes on the Uranian moon Miranda only measures, at most, 10 km tall, and that is currently the tallest known cliff in our solar system. The math must be wrong somewhere! [Update: According to a more recent NASA press release, the scarp is apparently nine miles (15 km) tall. That's certainly not anywhere near 37 km, but it may be about a third higher than Miranda's Verona Rupes. Impressive!]

New Crater on Titan

Impact craters are rare on Titan. Until recently only seven had been identified definitely on Titan, so it was exciting when Cassini's Titan Radar Mapper imaged an eighth impact crater on June 21, 2011. This newly discovered crater is about 25 miles (40 kilometers) in diameter and is surrounded by a continuous blanket of ejecta (material thrown out from the crater) that appears bright to radar and extends roughly 10 to 12 miles (15 to 20 kilometers) beyond the rim. With its well-preserved ejecta and steep inward-facing walls, the new crater resembles the two other freshest known craters on Titan: Sinlap, seen in the radar image of February 2005 (PIA07368), and Ksa, seen in September 2006 (PIA08737) and imaged again in this latest flyby. One difference is that Sinlap and the new crater seem to have flat, largely featureless floors, but Ksa has a bright central peak.

Dunes, visible as dark lines on the left of the image, have been swept toward the crater by the winds of Titan. These dunes have encroached very little onto the bright ejecta, compared to those on Ksa where more than a third of the ejecta blanket on its western edge is covered by dunes.

While Saturn's other moons have many thousands of craters, Titan has very few. One reason is that Titan's dense atmosphere burns up the smaller impacting bodies before they can reach the surface. The craters that do form are often hard to recognize or disappear entirely as they are eroded over time by geological processes such as the wind-driven motion of sand and, possibly, icy volcanism.

This synthetic-aperture radar (SAR) image, centered at 12 degrees north latitude and 45 degrees west longitude, measures 150 miles (242 kilometers) high by 160 miles (257 kilometers) wide, with resolution of about 350 meters per pixel; north is at the top, and the image is illuminated from the bottom. Incidence angle varies from 15 to 25 degrees.

Photo credit: NASA/JPL-Caltech

Hurricane Irene

NASA's Terra spacecraft passed over Hurricane Irene while it was just north of the Bahamas on August 25, 2011, at 11:45 a.m. EDT. At the time, Irene was a category three hurricane on the Saffir-Simpson scale, with maximum sustained winds of 115 mph (185 kph), and a minimum central pressure of 951 hPa, according to NOAA's National Hurricane Center. The storm made landfall in North Carolina on the morning of August 27 as a category one hurricane.

This set of images, acquired by the Multi-angle Imaging SpectroRadiometer (MISR) instrument on Terra on August 25, highlights geophysical parameters important to scientists studying these storms.

MISR uses nine cameras to capture images of the hurricane from different angles. The leftmost image is taken from an angle of 46 degrees. The storm is visible to the north of Cuba, which is located in the lower left of the image. Irene's eye is covered with clouds. Strong storms in the eyewall and the outer rain bands appear as bright, textured regions.

The multiple angles of MISR's cameras provide a stereographic view of Hurricane Irene. This information can be used to determine the height of the storm's cloud tops. As shown in the center image, these heights exceed 11 miles (18 kilometers) in the center of the storm, and in the outer rain bands, where the vertical motion is strongest. Lower clouds, at an altitude of about 5 miles (8 kilometers), are visible along the storm's northern edge.

The Moderate Resolution Imaging Spectroradiometer (MODIS) instrument also flies on Terra and measures cloud top temperatures. Higher clouds are colder, and the highest clouds in Hurricane Irene on August 25 had temperatures less than minus 100 degrees Fahrenheit (minus 73 degrees Celsius).

While there is good correspondence between the MISR cloud top heights and the MODIS cloud top temperatures, these two observations provide different insights into the behavior of clouds near the core of the storm. Researchers are studying how the two measurements can be used in combination to estimate hurricane intensity.

These images cover more than 800 miles (1,300 kilometers) in the north-south direction, and are centered near 27 degrees North latitude, 75.5 degrees West longitude.

Photo credit: NASA/GSFC/LaRC/JPL, MISR Team

Detection of Emerging Sunspot Regions

The first movie segment showing the detected travel-time perturbations before the emergence of active region 10488 in the photosphere. The first 10 seconds of the movie show intensity observations of the Sun. The intensity later fades out and the photospheric magnetic field is shown. In the next 20 seconds, we zoom in to a region where a sunspot group would emerge. The upper layer shows magnetic field observations at the surface and the lower layer shows simultaneous travel-time perturbations, detected at a depth of about 60,000 km. After the emergence, intensity observations show the full development of this active region, until it rotates out of view on the west solar limb.

The second movie segment showing the detected travel-time perturbations during the emergence of active region 11158. The first 12 seconds of the movie show photospheric intensity observations (orange color) of the region, and travel-time perturbations detected at a depth of about 60,000 km (blue-red color). The movie then shows sunspots (blue and orange) on the solar surface and coronal loops (light green) observed by SDO/AIA.

Video credit: SOHO/MDI, SDO/HMI

Note: For more information, see Sunspot Breakthrough.

The Eyes of the Virgin

This striking image, taken with the FORS2 instrument on the Very Large Telescope, shows a beautiful yet peculiar pair of galaxies, NGC 4438 and NGC 4435, nicknamed The Eyes. The larger of these, at the top of the picture, NGC 4438, is thought to have once been a spiral galaxy that was strongly deformed by collisions in the relatively recent past. The two galaxies belong to the Virgo Cluster and are about 50 million light-years away.

Photo credit: ESO/Gems project

Note: For more information, see VLT Looks into The Eyes of the Virgin.

Infrared Dark Clouds in the Milky Way

Typically if an astronomer wants to see into or through a thick dark cloud in space, they will use an infrared-sensing telescope. However, in this infrared image from NASA's Wide-field Infrared Survey Explorer, or WISE, there are some clouds that are so cool and thick that even infrared light coming from within or the background can't penetrate them. The black areas in this image -- called infrared dark clouds -- are exceptionally cold, dense cloud cores seen in silhouette against the bright diffuse infrared glow of the plane of the Milky Way galaxy. The clouds are a great example of why it is so useful for astronomers to be able to observe in many different wavelengths of light.

If you were to look at this same region of the sky through a backyard telescope, you would see a sea of stars packed together, similar to the thousands of blue stars seen here. You might also notice small patches of darkness that appear to block out the stars behind them. But what you wouldn't see are these beautiful clouds colored green, yellow and red in this image from WISE. Those are only seen in infrared light. In fact, the places where you see dark patches with your eyes are often the places where WISE sees bright clouds with its infrared "eyes." This is because those clouds are dense enough to block visible light, but not dense enough to block longer wavelengths of infrared light that WISE detects. In addition, they are too cool to shine in visible light but still warm enough to glow brightly in infrared light.

However, the darkest areas here are places where the cloud is extremely compact and chilly, so much so that it is opaque even in the infrared wavelengths that WISE sees. To see them glow, one would need to look in even longer wavelengths, for example those detected by the European Space Agency's Herschel mission, which has important NASA contributions

These dark clouds are so dense that if you were located in the middle of one of them, you wouldn't be able to see anything -- no stars, no galaxies, only darkness. This dense material will eventually result in the formation of new stars and planets.

This image was made from observations by all four infrared detectors aboard WISE. Blue and cyan (blue-green) represent infrared light at wavelengths of 3.4 and 4.6 microns, which is primarily light from stars. Green and red represent light at 12 and 22 microns, which is primarily light from warm dust.

Photo credit: NASA/JPL-Caltech/UCLA

'Y Dwarf' Chillin' in Space

This artist's conception illustrates what a "Y dwarf" might look like. Y dwarfs are the coldest star-like bodies known, with temperatures that can be even cooler than the human body. NASA's Wide-field Infrared Survey Explorer uncovered these elusive objects for the first time, using its heat-sensing, infrared vision. The telescope found six Y dwarfs, ranging in atmospheric temperatures from 350 degrees Fahrenheit (175 degrees Celsius) to less than about 80 degrees Fahrenheit (25 degrees Celsius).

Y dwarfs belong to a larger family of objects called brown dwarfs. Brown dwarfs begin their lives like stars but they never accumulate enough mass to fuse atoms steadily at their cores and shine with starlight -- as our Sun does so well. Instead, they fade and cool with time, giving off most of their light in infrared wavelengths.

WISE was able to pick up this faint glow for six Y dwarfs, which are the coldest class of brown dwarfs and the latest letter in the stellar classification scheme. This scheme describes stars of all temperatures, beginning with the hottest "O" stars and now ending with the coldest Y dwarfs. The entire scheme includes the classes: O, B, A, F, G, K, M, L, T, Y. Our yellow sun belongs to the G class of stars. M stars are colder than our sun, and reddish in color.

While the O through K classes are all considered stars, M and L objects are a mixture of stars and brown dwarfs, and T and Y objects are all brown dwarfs. The term "brown dwarfs" was chosen because at that time, astronomers didn't know what colors these objects would actually have at the visible wavelengths our eyes see, and brown is not a true color of light (there are no "brown photons"). Astronomers now know that T dwarfs would appear reddish, or magenta, to the eye. But they are not certain what color Y dwarfs are, since these objects have not been detected at visible wavelengths. The purple color shown here was chosen mainly for artistic reasons. In addition, the Y dwarf is illustrated as reflecting a faint amount of visible starlight from interstellar space.

Illustration credit: NASA/JPL-Caltech

Note: For more information, see NASA'S Wise Mission Discovers Coolest Class of Stars and Discovered: Stars as Cool as the Human Body.

Messier 101 - The Pinwheel Galaxy

A large spiral galaxy dominates this view from NASA's Wide-field Infrared Survey Explorer, or WISE. The galaxy, often called the Pinwheel galaxy, was designated object 101 in astronomer Charles Messier's catalog of fuzzy things in the sky that are not comets. Stargazers can find the galaxy with a pair of binoculars in the constellation Ursa Major (the Great Bear). It is located about 3.5 degrees east of the double stars Alcor and Mizar, the bend in the handle of the famous asterism the Big Dipper (an asterism is a pattern of stars in the sky, smaller than a constellation, that appear near each other but, in fact, are not associated together in space).

Messier 101 is a grand design spiral galaxy, which is a disk of hundreds of billions of stars with a small central bulge and prominent arms spiraling out from the center. In this case, we are seeing the disk face-on. In this image, stars appear blue because they are hotter and glow brightly in the shorter wavelengths observed by WISE. Cooler dust glows in the longer wavelengths seen by WISE, which are colored green and red here. The spiral arms contain slightly more stars than the rest of the disk, and most of the dust is concentrated in the arms as well. Along the spiral arms there are several bright spots colored red, including one that appears a short distance above and to the left of the galaxy. These are massive zones of star formation within the galaxy.

Messier 101 is a very large spiral galaxy. At nearly 200,000 light-years across, it is about twice the size of our Milky Way galaxy. Its high levels of star formation and very well-defined spiral arms are likely caused by gravitational interactions with neighboring galaxies.

One neighboring galaxy can be seen as a faint fuzzy purplish patch farther up and to the left of Messier 101, near the very top edge of the image. This is NGC 5477, an irregular dwarf galaxy that is probably associated with Messier 101. Another galaxy can also be seen in this view to the right of Messier 101 at the same height as the bright red spot at the bottom of M101, up and to the right of the bright star in that area. It appears as a fuzzy blue patch much smaller and fainter in appearance than Messier 101. This galaxy is cataloged as CGCG 272-018. While Messier 101 is about 24 million light-years away, CGCG 272-018 is much farther: about 92 million light-years away. When the light collected by WISE from CGCG 272-018 left this galaxy, dinosaurs still roamed the planet.

This image was made from observations by all four infrared detectors aboard WISE. Blue and cyan (blue-green) represent infrared light at wavelengths of 3.4 and 4.6 microns, which is primarily light from stars. Green and red represent light at 12 and 22 microns, which is primarily light from warm dust.

Photo credit: NASA/JPL-Caltech/UCLA

False-Color Image of Vesta's Equatorial Region

NASA's Dawn spacecraft obtained this false-color image with its framing camera on July 25, 2011. The view on the left was taken through the camera's clear filter (left) and the false-color version on the right is composed of images through three color filters composed to a false color ratio image (right).

In this false Red-Green-Blue (RGB) color scheme, red is used for the ratio of the brightness at wavelengths of 750 nanometers to the brightness at 440 nanometers, green is used for the ratio to the brightness of 750 nanometers to 920 nanometers and blue is used for the ratio to the brightness at 440 nanometers to 750 nanometers. Red-blue tones capture the visible continuum and green tones capture the relative strength of the ferrous absorption band at 1 micron. The images have a resolution of about 490 meters per pixel.

Photo credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

The Leo Triplet

Triplet of bright galaxies in the constellation of Leo (The Lion), together with a multitude of fainter objects: distant background galaxies and much closer Milky Way stars. The image hints at the power of the VST and OmegaCAM for surveying the extragalactic Universe and for mapping the low brightness objects of the galactic halo. This image is a composite created by combining exposures taken through three different filters. Light that passed through a near-infrared filter was colored red, light in the red part of the spectrum is colored green, and green light is colored magenta.

Photo credit: ESO/INAF-VST/OmegaCAM. Acknowledgement: OmegaCen/Astro-WISE/Kapteyn Institute

Notes: For more information, see VST Looks at the Leo Triplet — and Beyond. The galaxy to the left is NGC 3628; opposite it to the right is Messier 66, and in the top right corner is Messier 65.

Lyman-Alpha Blob-1

This image shows one of the largest known single objects in the Universe, the Lyman-alpha blob LAB-1. This picture is a composite of two different images taken with the FORS instrument on the Very Large Telescope (VLT) — a wider image showing the surrounding galaxies and a much deeper observation of the blob itself at the center made to detect its polarization. The intense Lyman-alpha ultraviolet radiation from the blob appears green after it has been stretched by the expansion of the Universe during its long journey to Earth. These new observations show for the first time that the light from this object is polarized. This means that the giant "blob" must be powered by galaxies embedded within the cloud.

Photo credit: ESO/M. Hayes

Note: For more information, see Giant Space Blob Glows from Within.

Antarctic Ice Flows

First complete map of the speed and direction of ice flow in Antarctica, derived from radar interferometric data from the Japan Aerospace Exploration Agency's ALOS PALSAR, the European Space Agency's Envisat ASAR and ERS-1/2, and the Canadian Space Agency's RADARSAT-2 spacecraft. The color-coded satellite data are overlaid on a mosaic of Antarctica created with data from NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on NASA's Terra spacecraft. Pixel spacing is 984 feet (300 meters). The thick black lines delineate major ice divides. Subglacial lakes in Antarctica's interior are also outlined in black. Thick black lines along the coast indicate ice sheet grounding lines.

Map credit: NASA/JPL-Caltech/UCI

Update (25 August 2011): Speaking of Antarctic ice, the Minister just came across this video of huge, city-sized chunks of ice being ripped off the Sulzberger Ice Shelf last March by waves from the Japanese tsunami. Below is a video that shows satellite images of the icebergs from NASA and ESA satellites:

Snowman Craters on Vesta

NASA's Dawn spacecraft obtained this image with its framing camera on August 6, 2011. This image was taken through the framing camera's clear filter aboard the spacecraft. The framing camera has a resolution of about 280 yards (260 meters) per pixel. North is pointing towards the two o'clock position.

Photo credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

European ALMA Antenna En Route to Installation

The first European antenna for the Atacama Large Millimeter/sub-millimeter Array (ALMA) reaches new heights, seen here being transported to the observatory’s Array Operations Site (AOS). The 12-meter diameter antenna arrived at the Chajnantor plateau, 5000 meters above sea level, to join antennas from the other international ALMA partners, bringing the total number at the AOS to 16. Although this sounds like just another number, 16 is the number of antennas specified for ALMA to begin its first science observations, and is therefore an important milestone for the project.

Photo credit: ESO/S. Stanghellini

Note: For more information and photos, see European ALMA Antenna Brings Total on Chajnantor to 16.

Impact Crater on the Edge of Oskison Crater

This image features a crater situated at the edge of the larger Oskison crater located in the plains north of Caloris basin. Due to MESSENGER's highly elliptical orbit, MDIS's Wide Angle Camera is capable of capturing higher resolution images in Mercury's northern hemisphere, such as this 58 meters per pixel view. A detailed look at the crater reveals its terraced walls, smooth floor, and its superposition on Oskison's shadowed rim.

Date acquired: August 01, 2011
Image Mission Elapsed Time (MET): 220677117
Image ID: 577219
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
WAC filter: 7 (748 nanometers)
Center Latitude: 60.18°
Center Longitude: 141.9° E
Resolution: 58 meters/pixel
Scale: This crater is approximately 39 km (24 mi) in diameter.
Incidence Angle: 81.2°
Emission Angle: 0.8°
Phase Angle: 80.5°

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

Helene

Saturn's small, irregularly shaped moon Helene is strikingly illuminated in this close view captured by Cassini during the spacecraft's June 18, 2011, flyby.

Although it is not visible at this exposure, the planet actually fills the dark background of this image of Helene. See PIA12773 for another close-up from this encounter.

This view looks toward the anti-Saturn side of Helene (33 kilometers, or 21 miles across). North on Helene is up. Lit terrain on the right is on the leading hemisphere while lit terrain at the top of the image surrounds the north pole.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera. The view was obtained at a distance of approximately 11,000 kilometers (7,000 miles) from Helene and at a Sun-Helene-spacecraft, or phase, angle of 151 degrees. Image scale is 67 meters (220 feet) per pixel.

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

Cerberus Fossae Fractures

Cerberus Fossae is an extensive fracture system in the southern part of Elysium Planitia.

These fractures have acted as a conduit for the release of water and lava onto the surface relatively recently in Martian geologic history. Dark sediment from the trough walls are visible, as well as some subsurface layers.

This is a stereo pair with PSP_004006_1900.

Photo credit: NASA/JPL/University of Arizona

30 New Open Star Clusters

Using data from the VISTA infrared survey telescope at ESO’s Paranal Observatory, an international team of astronomers has discovered 96 new open clusters hidden by the dust in the Milky Way. Thirty of these clusters are shown in this mosaic. These tiny and faint objects were invisible to previous surveys, but they could not escape the sensitive infrared detectors of the world’s largest survey telescope, which can peer through the dust. This is the first time so many faint and small clusters have been found at once. The images are made using infrared light in the following bands: J (shown in blue), H (shown in green), and Ks (shown in red).

Photo credit: ESO/J. Borissova

For more information, see VISTA Finds 96 Star Clusters Hidden Behind Dust.

Messier 27 - The Dumbbell Nebula

The "Dumbbell nebula," also known as Messier 27, pumps out infrared light in this image from NASA's Spitzer Space Telescope. The nebula was named after its resemblance to a dumbbell as seen in visible light. It was discovered in 1764 by Charles Messier, who included it as the 27th member of his famous catalog of nebulous objects. Though he did not know it at the time, this was the first in a class of objects, now known as "planetary nebulae," to make it into the catalog.

Planetary nebulae, historically named for their resemblance to gas-giant planets, are now known to be the remains of stars that once looked a lot like our Sun. When sun-like stars die, they puff out their outer gaseous layers. These layers are heated by the hot core of the dead star, called a white dwarf, and shine with infrared and visible-light colors. Our own Sun will blossom into a planetary nebula when it dies in about five billion years.

The Dumbbell nebula is 1,360 light-years away in the Vulpecula constellation, and stretches across 4.5 light-years of space. That would more that fill the space between our Sun and the nearest star, and it demonstrates how effective planetary nebulae are at returning much of a star's material back to interstellar space at the end of their lives.

Spitzer's infrared view shows a different side of this recycled stellar material. The diffuse green glow, which is brightest near the center, is probably from hot gas atoms being heated by the ultraviolet light from the central white dwarf.

A collection of clumps fill the central part of the nebula, and red-colored radial spokes extend well beyond. Astronomers think these features represent molecules of hydrogen gas, mixed with traces of heavier elements. Despite being broken apart by the ultraviolet light from the central white dwarf, much of this molecular material may survive intact and mix back into interstellar gas clouds, helping to fuel the next generation of stars. Similar structures are seen in the Helix and other planetary nebulae.

This image was made using data from Spitzer's infrared array camera. Blue shows infrared light with wavelengths of 3.6 microns, green represents 4.5-micron light and red, 8.0-micron light.

Photo credit: NASA/JPL-Caltech/Harvard-Smithsonian CfA

The West Rim of Endeavour Crater

A portion of the west rim of Endeavour crater sweeps southward in this color view from NASA's Mars Exploration Rover Opportunity. This crater -- with a diameter of about 24 miles (22 kilometers) -- is more than 25 times wider than any that Opportunity has previously approached during the rover's 90 months on Mars.

This view combines exposures taken by Opportunity's panoramic camera (Pancam) on the 2,678th Martian day, or sol, of the rover's work on Mars (August 6, 2011) before driving on that sol. The subsequent Sol 2678 drive covered 246 feet (75.26 meters), more than half of the remaining distance to the rim of the crater. Opportunity arrived at the rim during its next drive, on Sol 2681 (August 9, 2011).

Endeavour crater has been the rover team's destination for Opportunity since the rover finished exploring Victoria crater in August 2008. Endeavour offers access to older geological deposits than any Opportunity has seen before.

The closest of the distant ridges visible along the Endeavour rim is informally named "Solander Point." Opportunity may investigate that area in the future. The rover's first destination on the rim, called "Spirit Point" in tribute to Opportunity's now-inactive twin, Spirit, is to the left (north) of this scene.

The lighter-toned rocks closer to the rover in this view are similar to the rocks Opportunity has driven over for most of the mission. However, the darker-toned and rougher rocks just beyond that might be a different type for Opportunity to investigate.

The ground in the foreground is covered with iron-rich spherules, nicknamed "blueberries," which Opportunity has observed frequently since the first days after landing. They are about 0.2 inch (5 millimeters) or more in diameter.

This view combines images taken through three different Pancam filters admitting light with wavelengths centered at 753 nanometers (near infrared), 535 nanometers (green) and 432 nanometers (violet). This "natural color" is the rover team's best estimate of what the scene would look like if humans were there and able to see it with their own eyes. Seams have been eliminated from the sky portion of the mosaic to better simulate the vista a person standing on Mars would see.

Photo credit: NASA/JPL-Caltech/Cornell/Arizona State University (natural color; false color)

NGC 3521

This picture of the nearby galaxy NGC 3521 was taken using the FORS1 instrument on ESO’s Very Large Telescope, at the Paranal Observatory in Chile. The large spiral galaxy lies in the constellation of Leo (The Lion), and is only 35 million light-years distant. This picture was created from exposures taken through three different filters that passed blue light, yellow/green light, and near-infrared light. These are shown in this picture as blue, green, and red, respectively.

Photo credit: ESO/O. Maliy

Note: For more information, see A Spiral in Leo.

Oxygen Molecules Found in the Orion Nebula

This image shows the Orion Nebula, an iconic stellar nursery where stars are formed out of a dense mixture of gas and dust. A recent study, conducted with ESA's Herschel Space Observatory, has finally found the first robust evidence of molecular oxygen (O2), among the various chemical species in the nebula.

The inset on the right-hand side shows three distinct lines emitted by oxygen molecules, at frequencies of 1121, 774 and 487 GHz, respectively, in the spectra taken with the HIFI spectrometer on board Herschel. As with many other molecules, O2 produces a number of lines at a distinct set of wavelengths, corresponding to energy released by the molecule as it undergoes changes in its rotation. These spectral lines are used by astronomers to track down the presence of a molecule in cosmic sources.

Herschel data have revealed O2 in a dense patch of gas and dust adjacent to star-forming regions in the Orion Nebula. Astronomers believe that oxygen freezes out on dust grains in molecular clouds. However, in some spots, such as the one where O2 has been found, neighboring newborn stars heat the icy grains, causing water ice to evaporate and re-establishing chemical reactions that result in the formation of O2.

The image of the Orion Nebula was taken in infrared light by NASA's Spitzer Space Telescope.

Photo credit: ESA/NASA/JPL-Caltech

Note: For more information, see Herschel uncovers 'hidden' oxygen in Orion.

Tethys and Titan

The Cassini spacecraft views the cratered surface of Saturn's moon Tethys in front of the hazy orb of the planet's largest moon, Titan. Tethys (1,062 kilometers, or 660 miles across) is much closer than Titan (5,150 kilometers, or 3,200 miles across) to Cassini. This view looks toward the Saturn-facing side of Titan and toward the area between the trailing hemisphere and anti-Saturn side of Tethys. Saturn is out of the frame, far to the left.

The image was taken in visible green light with the Cassini spacecraft narrow-angle camera on July 14, 2011. The view was acquired at a distance of approximately 3.2 million kilometers (2 million miles) from Titan and at a Sun-Titan-spacecraft, or phase, angle of 18 degrees. Image scale is 19 kilometers (12 miles) per pixel on Titan. The view was acquired at a distance of approximately 1.9 million kilometers (1.2 million miles) from Tethys and at a Sun-Tethys-spacecraft, or phase, angle of 18 degrees. Image scale is 11 kilometers (7 miles) per pixel on Tethys.

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

An Active Galactic Nucleus According to the Unified Model

This image shows an artist's impression of an Active Galactic Nucleus (AGN) within the currently leading scenario, the so-called unified model.

An AGN consists of a supermassive black hole lying at the core of a massive galaxy and accreting the surrounding matter at extraordinary rates, thus radiating profusely across the entire electromagnetic spectrum. These sources are often so bright that they outshine their host galaxies and have been detected out to the far reaches of the observable Universe.

The unified model explains the wide variety of features discerned in different classes of AGN in terms of the anisotropic geometry of the black hole's immediate surroundings. The accreting black hole is fed via a disc, and a thick, obscuring torus of gas and dust is believed to encompass the disc and to absorb part of the radiation it emits. The torus is shown in the image.

Depending on the orientation of the torus with respect to an observer's line of sight, the view to the galactic nucleus may be obstructed to varying degrees, giving rise to differences in the observed brightness and spectra of various classes of AGN. In addition, in some cases (known as radio-loud AGN), jets of energetic particles emanating from the vicinity of the black hole are observed, whereas in other cases (known as radio-quiet AGN) jets have not been detected.

Illustration credit: ESA/NASA, the AVO project and Paolo Padovani

Note: For more information, see INTEGRAL Observations Suggest Unified Model for Active Galactic Nuclei Requires a Rethink.

The Launch of Juno

The first video is an "official" video, compiled from several different camera angles and including, toward the end, some animation sequences showing events in the launch sequence that could not be captured with cameras. The second video is a compilation of a number of launch videos from various cameras both on the ground and on board the rocket.

NASA's Juno spacecraft is on its way to Jupiter after being launched aboard an Atlas V rocket from the Cape Canaveral Air Force Station, Florida on August 5 at 11:25 a.m. Eastern. The solar-powered spacecraft will arrive at Jupiter in July 2016 and orbit its poles 33 times to find out more about the gas giant's interior, atmosphere and aurora. Scientists believe Jupiter holds the key to better understanding the origins of our solar system.

Video credit: NASA

Warm-Season Flows on Slope in Horowitz Crater

This series of images shows warm-season features that might be evidence of salty liquid water active on Mars today. Evidence for that possible interpretation is presented in a report by McEwen et al. in the Aug. 5, 2011, edition of Science.

These images come from observations of Horowitz crater, at 32 degrees south latitude, 141 degrees east longitude, by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter. In time, the series spans from late summer of one Mars year to mid-summer of two years later. The images taken from oblique angles have been adjusted so that all steps in the sequence show the scene as if viewed from directly overhead.

The features that extend down the slope during warm seasons are called recurring slope lineae. They are narrow (one-half to five yards or meters wide), relatively dark markings on steep (25 to 40 degree) slopes at several southern hemisphere locations. Repeat imaging by HiRISE shows the features appear and incrementally grow during warm seasons and fade in cold seasons. They extend downslope from bedrock outcrops, often associated with small channels, and hundreds of them form in rare locations. They appear and lengthen in the southern spring and summer from 48 degrees to 32 degrees south latitudes favoring equator-facing slopes. These times and places have peak surface temperatures from about 10 degrees below zero Fahrenheit to 80 degree above zero Fahrenheit (about 250 to 300 Kelvin). Liquid brines near the surface might explain this activity, but the exact mechanism and source of the water are not understood.

The series is timed to dwell two seconds on the first and last frames and one second on intermediate frames, though network or computer performance may cause this to vary.

The legend on each image gives the exact HiRISE observation number so that additional image products from the observation and information about the observation can be found on the HiRISE website (e.g., the first image of the series is from PSP_005787_1475, at http://hirise.lpl.arizona.edu/PSP_005787_1475).

The legend also marks the Mars year and seasonal identifier (Ls) for each image. The Mars years begin with the first years of Mars exploration by robot spacecraft. This sequence includes images from Mars Year 28 and Mars Year 30. Ls stands for longitude of the sun, dividing the year into 360 degrees to mark the seasons. Ls = 180 is the beginning of southern spring, Ls = 270 is the beginning of southern summer, and Ls = 360 (or 0) is the beginning of southern autumn.

Other imagery related to these new findings from the Mars Reconnaissance Orbiter is at http://www.nasa.gov/mission_pages/MRO/multimedia/gallery/gallery-index.html.

Photo credit: NASA/JPL-Caltech/University of Arizona

Juno Being Lowered into Position

At Space Launch Complex 41, the Juno spacecraft, enclosed in an Atlas payload fairing, was transferred into the Vertical Integration Facility where it was positioned on top of the Atlas rocket stacked inside.

Photo credit: NASA/Kennedy Space Center

Vesta in False Colors

NASA's Dawn spacecraft obtained this image of the giant asteroid Vesta with its framing camera on July 24, 2011. Scientists are studying image like these to better understand the different materials on the surface.

Photo credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Note: This caption is remarkably short on details about the above photo, but the picture is too nice not to publish.

A Snowman on Vesta

NASA's Dawn spacecraft obtained this image of the giant asteroid Vesta with its framing camera on July 24, 2011. It was taken from a distance of about 3,200 miles (5,200 kilometers). Dawn entered orbit around Vesta on July 15, and will spend a year orbiting the body. After that, the next stop on its itinerary will be an encounter with the dwarf planet Ceres.

Photo credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Notes: For more information, see NASA's Dawn Spacecraft Begins Science Orbits of Vesta. Also, a closeup view of the "Snowman Craters" can be found here.

Eye Toward Aegaeon

The Cassini spacecraft looks toward Saturn's tiny moon Aegaeon within the G-ring arc.

The moonlet Aegaeon (formerly known as S/2008 S 1) can't be seen in this image, but it orbits in the bright arc of Saturn's faint G ring shown here. See PIA11148 to learn more.

Many background stars are visibly elongated by the motion of the spacecraft during the image's exposure. This view looks toward the northern, sunlit side of the rings from just above the ringplane.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on July 4, 2011. The view was acquired at a distance of approximately 2.5 million kilometers (1.6 million miles) from Saturn. Image scale is 14 kilometers (9 miles) per pixel.

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

Rembrandt Basin

The large Rembrandt basin is evident on the left side of this image, and, in contrast to the relatively darker material surrounding Rembrandt, Amaral crater and its bright rays can be seen on the right. Rembrandt basin is an area of particular scientific interest due to its large size, young age, and extensional and contractional characteristics. In fact, Rembrandt was highlighted in a publication of Science magazine in 2009 and featured on the cover.

This image was acquired as part of MDIS's color base map. The color base map is composed of WAC images taken through eight different narrow-band color filters and will cover more than 90% of Mercury's surface with an average resolution of 1 kilometer/pixel (0.6 miles/pixel). The highest-quality color images are obtained for Mercury's surface when both the spacecraft and the Sun are overhead, so these images typically are taken with viewing conditions of low incidence and emission angles.

Date acquired: July 11, 2011
Image Mission Elapsed Time (MET): 218833662, 218833682, 218833666
Image ID: 489008 , 489013, 489009
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
WAC filter: 9 (1000 nanometers), 7 (750 nanometers), 6 (433 nanometers) as red-green-blue
Center Latitude: -34.67°
Center Longitude: 100.4° E
Resolution: 1853 meters/pixel
Scale: Rembrandt basin has a diameter of 716 kilometers (445 miles).
Incidence Angle: 50.5°
Emission Angle: 0.4°
Phase Angle: 50.5°

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