NASA Astronomy Picture of the Day 2008-6

A Twisted Solar Eruptive Prominence


Unusual Light Patch Under Phoenix Lander on Mars


The Dark River to Antares

Connecting the Pipe Nebula to the bright star Antares is a flowing dark cloud nicknamed the Dark River. The murkiness of the Dark River is caused by absorption of background starlight by dust, although the nebula contains mostly hydrogen and molecular gas. Antares, the bright star that appears yellow just below the center of the frame, is embedded in the colorful Rho Ophiuchi nebula clouds. The Dark River, pictured above across the upper left, spans over 20 times the angular diameter of the Moon and lies about 500 light years distant. Other types of nebulas visible here include red emission nebula and the blue reflection nebula. digg_url = ''; digg_skin = 'compact';

Chasing the ISS


Spitzer's Milky Way

The Spitzer Space Telescope's encompasing infrared view of the plane of our Milky Way Galaxy is hard to appreciate in just one picture. In fact, more than 800,000 frames of data from Spitzer's cameras have now been pieced together in an enormous mosaic of the galactic plane - the most detailed infrared picture of our galaxy ever made. The small portion seen here spans nearly 8 degrees, roughly the apparent width of your fist held at arms length, across the galaxy's center. The full mosaic is 120 degrees wide. Highlighted in the false-color presentation are curving green filaments of light from complex molecules - polycyclic aromatic hydrocarbons (PAHs) - that on Earth are the common, sooty products of incomplete combustion. The PAHs are found in star forming regions, along with reddish emission from graphite dust particles. Blue specks throughout the picture are individual Milky Way stars. digg_url = ''; digg_skin = 'compact';

Two-Armed Spiral Milky Way


June's Young Crescent Moon

Serene skyviews were enjoyed across planet Earth earlier this week with a young crescent Moon low in the western sky just after sunset. Recorded on June 4, this colorful example includes a quiet beach in the foreground with the city lights of Lisbon, Portugal, and the Sintra Mountains along the horizon. Posing between cloud banks, the Moon's slender, sunlit arc represents only about 1 percent of the full lunar disc. The rest of the Moon's nearside is faintly visible though, illuminated by Earthshine. A waxing crescent Moon should also create some lovely western skies at dusk this weekend. The bright star in the sky near tonight's (Saturday's) Moon will actually be the planet Mars. On Sunday the Moon will move closer to a pair of celestial beacons, bright star Regulus and Saturn. digg_url = ''; digg_skin = 'compact';

Mars Soil Sample Ready to Analyze

What surprises are hidden in the soils of Mars? To help find out, the Phoenix Lander Phoenix Lander which arrived on Mars two weeks ago has attempted to place a scoop of soil in Phoenix's Thermal and Evolved-Gas Analyzer (TEGA). Pictured above, the dirt-filled scoop approaches one of TEGA's eight ovens. Once in the oven, a soil material will be baked and the emitted gasses categorized by a mass spectrometer. Quite possibly, some of the light colored material visible in the scoop has the same composition as the light material imaged near the foot of the Lander, which may be ice. Phoenix is scheduled to spend the next three months digging, baking and chemically analyzing its immediate surroundings to better understand Mars and whether the boundary between ice and soil was ever capable of supporting life. digg_url = ''; digg_skin = 'compact';

Saturn's Rings from the Other Side

What do Saturn's rings look like from the other side? From Earth, we usually see Saturn's rings from the same side of the ring plane that the Sun illuminates them. Geometrically, in the above picture taken in April by the robot Cassini spacecraft now orbiting Saturn, the Sun is behind the camera but on the other side of the ring plane. This vantage point, specifically 17 degrees above the ring plane, gives a breathtaking views of the most splendid ring system in the Solar System. Strangely, the rings have similarities to a photographic negative of a front view. The ring brightness as recorded from different angles indicates ring thickness and particle density of ring particles. Elsewhere, ring shadows can be seen on the sunlit face of Saturn, shown sporting numerous cloud structures in nearly true color. digg_url = ''; digg_skin = 'compact';

A Fire Rainbow Over New Jersey


Dextre Robot at Work on the Space Station

What's the world's most complex space robot doing up there? Last week, Dextre was imaged moving atop the Destiny Laboratory Module of the International Space Station (ISS), completing tasks prior to the deployment of Japan's Kibo pressurized science laboratory. Dextre, short for the Canadian-built Special Purpose Dextrous Manipulator, has arms three meters in length and can attach power tools as fingers. Behind Dextre is the blackness of space, while Earth looms over Dextre's head. The Kibo laboratory segment being deployed during space shuttle Discovery's trip to the ISS can be pressurized and contains racks of scientific experiment that will be used to explore many things, including how plants brace themselves against gravity, and how water might be inhibited from freezing in cells under microgravity. digg_url = ''; digg_skin = 'compact'; News: GLAST spacecraft reaches orbit

Phoenix and the Snow Queen


At Last, GLAST

Rising through a billowing cloud of smoke, this Delta II rocket left Cape Canaveral Air Force Station's launch pad 17-B Wednesday at 12:05 pm EDT. Snug in the payload section was GLAST, the Gamma-ray Large Area Space Telescope, now in orbit around planet Earth. GLAST's detector technology was developed for use in terrestrial particle accelerators. But from orbit, GLAST can study gamma-rays from extreme environments in our own Milky Way galaxy, as well as supermassive black holes at the centers of distant active galaxies, and the sources of powerful gamma-ray bursts. Those cosmic accelerators achieve energies not attainable in earthbound laboratories. GLAST also has the sensitivity to search for signatures of new physics in the relatively unexplored high-energy gamma-ray regime. digg_url = ''; digg_skin = 'compact';

M51 Hubble Remix


Phoenix Digs for Clues on Mars

What's a good recipe for preparing Martian soil? Start by filling your robot's scoop a bit less than half way. Next, dump your Martian soil into one of your TEGA ovens, being sure to watch out for clumping. Then, slowly increase the temperature to over 1000 degrees Celsius over several days. Keep checking to see when your soil becomes vaporized. Finally, your Martian soil is not ready for eating, but rather sniffing The above technique is being used by the Phoenix Lander that arrived on Mars three weeks ago. Data from the first batch of baked soil should be available in a few days. Pictured above, a circular array of the Phoenix Lander's solar panels are visible on the left, while a scoop partly filled with Martian soil is visible on the right. The robotic Phoenix Lander will spend much of the next three months digging, scooping, baking, sniffing, zapping, dissolving, and magnifying bits of Mars to help neighboring Earthlings learn more about the hydrologic and biologic possibilities of the sometimes mysterious red planet. digg_url = ''; digg_skin = 'compact';

Inside the Coma Cluster of Galaxies


Eta Carinae and the Homunculus Nebula


Pyramid Ice Crystal Halos Over Finland


The Star Streams of NGC 5907


Solstice Moonrise, Cape Sounion


Vanishing Act

Compare these two close-up pictures taken on sol 20 (left) and sol 24 of a trench dug in the Martian surface by NASA's Phoenix Lander. Those sols of the Phoenix Mission (a sol is a Martian day), correspond to June 15 and 18 on planet Earth. Light-colored, dice-sized chunks, visible in the lower left shadow region of the trench in the sol 20 image have vanished by sol 24 -- a strong indication that the chunks were ice uncovered by digging the shallow trench. The vanishing act likely demonstrates the sublimation of ice in the trench, a process similar to evaporation, in which the ice went directly from solid to gas after it was exposed to sunlight and the thin, dry Martian atmosphere. digg_url = ''; digg_skin = 'compact';

Barred Spiral Galaxy NGC 1300


The International Space Station Expands Again

The developing International Space Station (ISS) has changed its appearance again. Earlier this month, the Space Shuttle orbiter Discovery visited the ISS and added components that included Japan's Kibo Science Laboratory. The entire array of expansive solar panels is visible in this picture taken by the Discovery Crew after leaving the ISS to return to Earth. The world's foremost space outpost can be seen developing over the past several years by comparing the above image to past images. Also visible above are many different types of modules, a robotic arm, another impressive set of solar panels, and a supply ship. Construction began on the ISS in 1998. digg_url = ''; digg_skin = 'compact';

Ithaca Chasma: The Great Rift on Saturn's Tethys

What created the Great Rift on Saturn's moon Tethys? No one is sure. More formally named Ithaca Chasma, the long canyon running across the right of the above image extends about 2,000 kilometers long and spreads as much as 100 kilometers wide. The above image was captured by the Saturn-orbiting robotic Cassini spacecraft as it zoomed by the icy moon last month. Hypotheses for the formation of Ithaca Chasma include cracking of Tethy's outer crust as the moon cooled long ago, and that somehow the rift is related to the huge Great Basin impact crater named Odysseus, visible elsewhere on the unusual moon. Cassini has now been orbiting Saturn for about four years and is scheduled to continue to probe and photograph Saturn for at least two more years. digg_url = ''; digg_skin = 'compact';

What is Hanny's Voorwerp?

What is that green thing? A volunteer sky enthusiast surfing through online Galaxy Zoo images has discovered something really strange. The mystery object is unusually green, not of any clear galaxy type, and situated below relatively normal looking spiral galaxy IC 2497. Dutch schoolteacher Hanny van Arkel, discovered the strange green "voorwerp" (Dutch for "object") last year. The Galaxy Zoo project encourages sky enthusiasts to browse through SDSS images and classify galaxy types. Now known popularly as Hanny's Voorwerp, subsequent observations have shown that the mysterious green blob has the same distance as neighboring galaxy IC 2497. Research is ongoing, but one leading hypothesis holds that Hanny's Voorwerp is a small galaxy that acts like a large reflection nebula, showing the reflected light of a bright quasar event that was visible in the center of IC 2497 about 100,000 years ago. Pictured above, Hanny's Voorwerp was imaged recently by the 2.5-meter Isaac Newton Telescope in the Canary Islands by Dan Smith, Peter Herbert and Chris Lintott (Univ. Hertfordshire). Other collaboration members include Matt Jarvis, Kevin Schawinski, and William Keel. digg_url = ''; digg_skin = 'compact';

M27: Not A Comet


M81: Feeding a Black Hole

This impressive color composite shows spiral galaxy M81 across the electromagnetic spectrum. It combines X-ray data (blue) from the Chandra Observatory, infrared data (pink) from the Spitzer Space Telescope, and an ultraviolet image (purple) from the GALEX satellite, with a visible light (green) Hubble image. The inset highlights X-rays from some of M81's black holes, including black holes in binary star systems with about 10 times the mass of the sun, as well as the central, supermassive black hole of over 70 million solar masses. Comparing computer models of the giant black hole's energy output to the multiwavelength data suggests that feeding that monster is relatively simple -- energy and radiation is generated as material in the central region swirls inwards forming an accretion disk. In fact, the process otherwise appears to be just like the accretion process feeding M81's stellar mass black holes, even though the central black hole is millions of times more massive. M81 itself is about 70,000 light-years across and only 12 million light-years away in the northern constellation Ursa Major. digg_url = ''; digg_skin = 'compact';

Fireball at Ayers Rock

A weekend trip for astrophotography in central Australia can result in gorgeous skyscapes. In this example recorded in March of 2006, the center of our Milky Way Galaxy rises over planet Earth's horizon and the large sandstone formation called Uluru, also known as Ayers Rock. After setting up two cameras to automatically image this celestial scene in a series of exposures, one through a wide-angle and the other through a telephoto lens, photographer Joseph Brimacombe briefly turned his back to set up other equipment. To his surprise, the ground around him suddenly lit up with the brilliant flash of a fireball meteor. To his delight, both cameras captured the bright meteor streak. Highlighted in the telephoto view (inset), the fireball trail shines through cloud banks, just left of Ayers Rock. digg_url = ''; digg_skin = 'compact';

Shadow of a Martian Robot

What if you saw your shadow on Mars and it wasn't human? Then you might be the Opportunity rover currently exploring Mars. Opportunity and sister robot Spirit have been probing the red planet since early 2004, finding evidence of ancient water, and sending breathtaking images across the inner Solar System. Pictured above, Opportunity looks opposite the Sun into Endurance Crater and sees its own shadow. Two wheels are visible on the lower left and right, while the floor and walls of the unusual crater are visible in the background. Opportunity and Spirit have now spent over four years exploring the red world, find new clues into the wet ancient past of our Solar System's second most habitable planet. digg_url = ''; digg_skin = 'compact';

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