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2008 May 15 Sideways Galaxy NGC 3628 Credit & Copyright: Keith QuattrocchiDark dust lanes cut across the middle of this gorgeousisland universe, a strong hint thatNGC 3628 is a spiral galaxyseen sideways.About 35 million light-years away in thenorthern springtimeconstellationLeo, NGC 3628 alsobears the distinction of being the only member of the well knownLeotriplet of galaxies not in CharlesMessier’s famous catalog.Otherwise similar in size to ourMilky WayGalaxy, the disk ofNGC 3628 is clearly seen to fan out near the edges.A faint arm of material also extends to the left inthis sharp and deep view of the region.The distorted shape and fainttidal tail suggest thatNGC 3628is interacting gravitationally with the other spiral galaxies inthe Leo triplet,M66 and M65.circle ’round the sun

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Astronomy Picture of the DayNebula 2008 May 12 The M81 Galaxy Group Through the Integrated Flux Nebula Credit & Copyright: Jordi GallegoLarge galaxies and faint nebula highlight this deep image of the M81Group of galaxies. First and foremost in the above wide-angle 12-hour exposure is the grand design spiral galaxyM81, the largest galaxyvisible in the image. M81 is gravitationally interacting with M82 just below it, a big galaxy with an unusual halo of filamentaryred-glowing gas. Around the image many other galaxies from the M81Group of galaxies can be seen. Together with other galaxy congregatesincluding our LocalGroup of galaxies and the Virgo Cluster of galaxies,the M81 Group is part of the expansive VirgoSupercluster of Galaxies. This whole galaxy menagerie is seen through the faintnebular glow of the IntegratedFlux Nebula, a little studied complex of diffuse gas and dust clouds in our Milky Way Galaxy. moon of saturn

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2008 May 11 Retrograde Mars Tunç TezelWhy would Mars appear to move backwards? Most of the time, the apparent motion of Mars in Earth’s sky is in one direction, slow but steady in front of the far distant stars. About every two years, however, the Earth passes Marsas they orbit around the Sun. During the most recent such pass over the last year, the proximity of Mars made the red planet appear larger and brighter than usual. Also during this time, Mars appeared to move backwards in the sky, a phenomenon called retrograde motion. Pictured above is a series of images digitally stacked so that all of the stars images coincide. Here, Mars appears to trace out a loop in the sky. Near the top of the loop, Earth passed Mars and the retrograde motion was the highest. Retrogrademotioncan also be seen for other Solar System planets. open space

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nearby galaxies

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2008 May 10 Stars and Mars Doug Zubenel(Wandering throughthe evening sky,on May 4th planet Marsstood in line with Castor and Pollux,the two bright stars of the constellationGemini. In this time exposure of the celestial alignment,Mars actually takes on a distinct yellowishhue, contrasting in color withPollux;a giant star known to have aJupiter-class planet,andCastor;itself a multiple star system.Though inmythologyPollux and Castor are twin brothers,the two stars are physically unrelated and are about 34 and 50light-years distant respectively.Included in the skyview areProcyon,alpha star of Canis Minor, andfamous star cluster M44 also known as theBeehive Cluster.Dust in our own solar system reflecting sunlightcreates the faint band ofZodiacal light emerging from thelower right corner of the frame.Just put your cursor over the picture for helpwith identifications.Of course, bright Mars can stillbefound in the westernevening skies and tonight wandersnear the crescent Moon.Mars, backwards

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2008 May 9 Moon Meets Mercury P-M Hedén(Clear Skies,TWAN)On Tuesday, May 6, while standing onplanet Earthand sweeping your binoculars along the western horizon justafter sunset,you might have encountered this arresting skyscape.The view features a slender crescent Moon andbright planet Mercury separated on the sky by onlyabout 2 degrees.Cradled in thesunlit lunar crescent, the nightside of the Moon is faintly illuminated by earthshine –sunlight reflected from planet Earth.Of course, the clouds in silhouette and fading twilight colorsare common elements in pictures of the sky after sunset,but much less often seen is inner planet Mercury,usually hidingclose to the Sun in Earth’s sky.Still, the coming week will be agoodtime tospot Mercury near the western horizonabout 30 minutes after sunset.As for the Moon,tonight andtomorrownight the crescent Moon will wander close to Marsin the early evening sky.Stars and Mars

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2008 May 8 The Dark Tower in Scorpius Credit & Copyright: Robert GendlerIn silhouette against a crowded star fieldtoward the constellationScorpius,this dusty cosmic cloud evokes for some the image of an ominousdark tower.In fact, clumps of dust and molecular gascollapsingto form stars may well lurk within the dark nebula,a structure that spans almost 40 light-years across thegorgeoustelescopic view.Known as acometary globule, the swept-back cloud,extending from the upper right to the head (top of the tower) left andbelow center, is shaped by intense ultraviolet radiation fromthe OB association of very hot starsin NGC6231, off the left edge of the scene.That energetic ultraviolet light also powers the globule’s borderingreddish glow of hydrogen gas.Hot stars embedded in the dustcan be seen as small bluishreflection nebulae.This dark tower,NGC 6231, andassociated nebulae are about 5,000 light-years away.when Moon meets Mercury

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2008 May 2 Shaping NGC 6188 Credit & Copyright: John EbersoleDark shapes with bright edges winging their way through dustyNGC 6188are tens of light-years long.The emission nebula is found near the edge of an otherwisedark large molecular cloud in the southernconstellationAra, about 4,000 light-years away.Formedin that region only a few million years ago, the massive youngstars of the embedded AraOB1 associationsculpt the fantastic shapes and power the nebular glow withstellar winds and intense ultraviolet radiation.The recentstarformation itself was likely triggered bywinds and supernova explosions, from previous generations of massivestars, that swept up and compressed the molecular gas.A false-colorHubble palette was used tocreate the this gorgeous wide-field imageand shows emission from sulfur, hydrogen, and oxygen atomsin red, green, and blue hues.At the estimated distance of NGC 6188, the picture spansabout 300 light-years.milky way pan

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to the Dark Tower

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2008 May 7 The Gegenschein Over Chile Credit & Copyright: Yuri BeletskyESOIs the night sky darkest in the direction opposite the Sun?No. In fact, a rarely discernable faint glow known as the gegenschein (German for “counter glow”) can be seen 180 degrees around from the Sun in an extremely dark sky.The gegenschein is sunlight back-scattered off small interplanetarydust particles. These dust particles are millimeter sized splinters from asteroids and orbit in the ecliptic plane of the planets. Pictured above from last October is one of the most spectacular pictures of the gegenschein yet taken.Here a deep exposure of an extremely dark sky over Paranal Observatory in Chile shows the gegenschein so clearly that even a surrounding glow is visible. In the foreground are several of the European Southern Observatory‘sVery Large Telescopes, while notable background objects include the Andromeda galaxy toward the lower left and the Pleiades star cluster just above the horizon. The gegenscheinis distinguished from zodiacal light near the Sun by the high angle of reflection. During the day, a phenomenon similar to the gegenschein called the glory can be seen in reflecting air or clouds opposite the Sun from an airplane. open space

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