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Winter Night at Pic du Midi Credit & Copyright: Alain Sallez (picdumidi.org), David Romeuf (Université Lyon 1) Explanation: This dreamlike view looking south from the historic mountain top Pic du Midi Observatory combines moonlit domes, a winter night sky, and the snowy peaks of the French Pyrenees. Encroaching on the night, lights from the La Mongie ski resort illuminate the mountain slopes nearby while the glow along the distant horizon is from urban areas in southern France and Spain. The night sky features stars of the constellations Orion and Gemini with a bright planet Mars very near the top edge,...

Orbiting Astronaut Reflects Earth Credit: Clayton C. Anderson, Expedition 15 Crew, NASA Explanation: Astronaut self-portraits can be particularly interesting. Visible in the above picture, working in from the outer borders, are the edges of the reflecting helmet of a space suit, modules of the International Space Station (ISS), the Earth, the arms of Expedition 15 astronaut Clay Anderson, and the digital camera used to snap the image. This picture was taken during the shuttle orbiter Endeavour's mission to expand the space station last August. The large curvature of the Earth appearing in the visor reflection is not the true curvature...

Mercury's Horizon from MESSENGER Credit: MESSENGER Teams, JHU APL, NASA Explanation: What would it look like to fly past Mercury? Just such an adventure was experienced last week by the MESSENGER spacecraft during its first flyby of the strange moon-like world nearest the Sun. Pictured above is the limb of Mercury seen by MESSENGER upon approach, from about 1 1/2 Earth diameters away. Visible on the hot and barren planet are many craters, many appeared to be more shallow than similarly sized craters on the Moon. The comparatively high gravity of Mercury helps flatten tall structures like high crater walls....

Supernova Factory NGC 2770 Credit: A. de Ugarte Postigo (ESO) et al., Dark Cosmology Centre (NBI, KU), Instituto de Astrofísica de Andalucía (CSIC), University of Hertfordshire Explanation: The stellar explosions known as supernovae are among the most powerful events in the universe. Triggered by the collapsing core of a massive star or the nuclear demise of a white dwarf, supernovae occur in average spiral galaxies only about once every century. But the remarkable spiral galaxy NGC 2770 has lately produced more than its fair share. Two still bright supernovae and the location of a third, originally spotted in 1999 but...

Thor's Emerald Helmet Credit & Copyright: Robert Gendler Explanation: This helmet-shaped cosmic cloud with wing-like appendages is popularly called Thor's Helmet. Heroically sized even for a Norse god, Thor's Helmet is about 30 light-years across. In fact, the helmet is actually more like an interstellar bubble, blown as a fast wind from the bright, massive star near the bubble's center sweeps through a surrounding molecular cloud. Known as a Wolf-Rayet star, the central star is an extremely hot giant thought to be in a brief, pre-supernova stage of evolution. Cataloged as NGC 2359, the nebula is located about 15,000 light-years...

MESSENGER Passes Mercury Credit: MESSENGER Teams, JHU APL, NASA Explanation: Two days ago, the MESSENGER spacecraft became only the second spacecraft in human history to swoop past Mercury. The last spacecraft to visit the Sun's closest planet was Mariner 10 over 35 years ago. Mariner 10 was not able to photograph Mercury's entire surface, and the images it did send back raised many questions. Therefore, much about planet Mercury remains unknown. This week's flyby of MESSENGER was only the first of three flybys. Over the next few years MESSENGER will swing past twice more and finally enter Mercury's orbit in...

The Cocoon Nebula from CFHT Credit & Copyright: Jean-Charles Cuillandre (CFHT), Hawaiian Starlight, CFHT Explanation: What creates the colors of the Cocoon Nebula? The Cocoon Nebula, cataloged as IC 5146, is a strikingly beautiful nebula located about 4,000 light years away toward the constellation of the Swan (Cygnus). Inside the Cocoon Nebula is a newly developing open cluster of stars. Like other stellar nurseries, the Cocoon Nebula holds, at the same time, a bright red emission nebula, blue reflection nebulas, and dark absorption nebulas. Given different mixtures, these three processes create a host of colors in this image taken recently...

Hurricane Ivan from the Space Station Credit: Expedition 9 Crew, International Space Station, NASA Explanation: Ninety percent of the houses on Grenada were damaged by the destructive force of Hurricane Ivan. At its peak, Ivan was a Category 5 hurricane, the highest power category on the Saffir-Simpson Scale, and created sustained winds in excess of 200 kilometers per hour. Ivan was the largest hurricane to strike the US in 2004, and, so far, the 10th most powerful in recorded history. As it swirled in the Atlantic Ocean, the tremendous eye of Hurricane Ivan was photographed from above by the orbiting...

Mercury Chases the Sunset Image Credit & Copyright: Doug Zubenel Explanation: This colorful view of the western sky at sunset features last Wednesday's slender crescent Moon. Of course, when the Moon is in its crescent phase it can never be far from Sun in the sky. Also always close to the Sun in Earth's sky is innermost planet Mercury, seen here below and right of center against the bright orange glow along the horizon. Mercury is usually difficult to glimpse because of the overwhelming sunlight, but increasingly better views of the small planet near sunset will be possible as it...

Active Galaxy Centaurus A Credit: X-ray - NASA, CXC, R.Kraft (CfA), et al.; Radio - NSF, VLA, M.Hardcastle (U Hertfordshire) et al.; Optical - ESO, M.Rejkuba (ESO-Garching) et al. Explanation: A mere 11 million light-years away, Centaurus A is a giant elliptical galaxy - the closest active galaxy to Earth. This remarkable composite view of the galaxy combines image data from the x-ray ( Chandra), optical(ESO), and radio(VLA) regimes. Centaurus A's central region is a jumble of gas, dust, and stars in optical light, but both radio and x-ray telescopes trace a remarkable jet of high-energy particles streaming from the...

Hidden Galaxy IC 342 from Kitt Peak Credit & Copyright: T. Rector (U. Alaska Anchorage), H. Schweiker, WIYN, NOAO, AURA, NSF Explanation: Beautiful nearby spiral galaxy IC 342 could be more famous if it wasn't so hidden. A sprawling island universe, IC 342 would be a prominent galaxy in our night sky, but it is almost hidden from view behind the veil of stars, gas and dust clouds in the plane of our Milky Way galaxy. Similar in size to other large, bright spiral galaxies IC 342 is a mere 7 million light-years distant in the long-necked, northern constellation of...

A Jupiter-Io Montage from New Horizons Credit: NASA, Johns Hopkins U. APL, SWRI Explanation: As the New Horizons spacecraft sweeps through the Solar System, it is taking breathtaking images of the planets. In February of last year, New Horizons passed Jupiter and the ever-active Jovian moon Io. In this montage, Jupiter was captured in three bands of infrared light making the Great Red Spot look white. Complex hurricane-like ovals, swirls, and planet-ringing bands are visible in Jupiter's complex atmosphere. Io is digitally superposed in natural color. Fortuitously, a plume was emanating from Io's volcano Tvashtar. Frost and sulfuric lava cover...

Quadrantid Meteors and Aurora from the Air Credit: Jeremie Vaubaillon et al., Caltech, NASA Explanation: Where do meteor showers originate? To help answer this question, astronomers studied in some detail the Quadrantid meteor shower that occurred over this past weekend. In particular, astronomers with specialized cameras flew as part of the Quadrantid's Multi-Instrument Aircraft Campaign (MAC) aboard a NASA DC-8 aircraft above northern Canada over the past few days and studied the Quadrantid meteor shower in unprecedented detail. Pictured above is a composite image combining many short exposures. Visible in the image are the tail of the airplane reflecting a...

Jupiter's Rings Revealed Credit: (NOAO), J. Burns (Cornell) et al., Galileo Project, JPL, NASA Explanation: Why does Jupiter have rings? Jupiter's rings were discovered in 1979 by the passing Voyager 1 spacecraft, but their origin was a mystery. Data from the Galileo spacecraft that orbited Jupiter from 1995 to 2003 later confirmed that these rings were created by meteoroid impacts on small nearby moons. As a small meteoroid strikes tiny Adrastea, for example, it will bore into the moon, vaporize, and explode dirt and dust off into a Jovian orbit. Pictured above is an eclipse of the Sun by Jupiter,...

The Milky Way at 5000 Meters Credit & Copyright: Serge Brunier Explanation: Climb up to 5000 meters (16,500 feet) above sea level, near Cerro Chajnantor in the northern Chilean Andes, and your night sky could encompass this cosmic vista. Recorded from that high and dry locale, the spectacular fish-eye image features the myriad stars and sprawling dust clouds of our Milky Way Galaxy. The direction toward the center of the Galaxy is near the zenith and center of the picture, but the Galactic Center itself is hidden from view, located far behind the obscuring dust. Brilliant Jupiter rules this scene...

Geminids in 2007 Credit & Copyright: Erno Berko Explanation: Dust from curious near-Earth asteroid 3200 Phaethon seems to fall from the constellation Gemini in this fisheye skyview. The composite image was recorded over four December nights (12-15) just last year from Ludanyhalaszi, Hungary. Of course, the streaks are meteor trails from the annual Geminids meteor shower. The work of astronomer Erno Berko, the finished picture combines 113 different frames and captures 123 separate meteors. The Geminids is one of the northern skies most reliably performing meteor showers and did not disappoint last year. Under good conditions some skywatchers reported well...

A Galaxy is not a Comet Credit & Copyright: Emiel Kempen Explanation: This gorgeous galaxy and comet portrait was recorded on December 30th, in the skies over Hoogeveen, The Netherlands. The combined series of 60 x 60 second exposures finds the lovely green coma of Comet 8P/Tuttle near its predicted conjunction with the Triangulum Galaxy. Aligning each exposure with the stars shows the comet as a streak, slowly moving against the background stars and galaxy. An alternative composition with exposures centered on the comet, shows the background stars and galaxy as streaks. The alluring celestial scene would also have been...

Rays from an Unexpected Aurora Credit & Copyright: Lyndon Anderson (Prairie Journal) Explanation: This aurora was a bit of a surprise. For starters, on this day in 2002, no intense auroral activity was expected at all. Possibly more surprising, however, the aurora appeared to show an usual structure of green rays from some locations. In this view, captured from North Dakota, USA, a picket fence of green rays stretches toward the horizon. Mirroring the green rays is a red band, somewhat rare in its own right. Lights from the cities of Bismarck and Mandan are visible near the horizon.

A Year of Spectacular Comets Credit & Copyright: Bob Nanz (San Diego Astronomy Association) Explanation: Two spectacular comets graced Earth's skies during 2007. Both comets became bright enough to be seen by the unaided eye of the casual sky enthusiast. Early in 2007, Comet McNaught grew brighter than any comet in 40 years, displaying a beautiful dust tail that flowed across the sky. Comet McNaught (c/2006 P1) became known as the Great Comet of 2007, sported unusual striations in its expansive dust tail, and showed unexpectedly complex chemistry in its ion tail. Toward the year's end, normally docile and faint...

Saturn's Infrared Glow Credit: VIMS Team, U. Arizona, ESA, NASA Explanation: Known for its bright ring system and many moons, gas giant Saturn looks strange and unfamiliar in this false-color view from the Cassini spacecraft. In fact, in this Visual and Infrared Mapping Spectrometer (VIMS) mosaic the famous rings are almost invisible, seen edge-on cutting across picture center. The most striking contrast in the image is along the terminator or boundary between night and day. To the right (day side) blue-green hues are visible sunlight reflected from Saturn's cloud tops. But on the left (night side) in the absence of...