Cataclysmic Dawn Cataclysmic Dawn

Will this dawn bring another nova? Such dilemmas might be pondered one day by future humans living on a planet orbiting a cataclysmic variable binary star system. Cataclysmic variables involve gas falling from a large star onto an accretion disk surrounding a massive but compact white dwarf star. Explosive cataclysmic events such as a dwarf nova can occur when a clump of gas in the interior of the accretion disk heats up past a certain temperature. At that point, the clump will fall more quickly onto the white dwarf and land with a bright flash. Such dwarf novas will not destroy either star, and may occur irregularly on time scales from a few days to tens of years. Although a nova is much less energetic than a supernova, if recurrent novas are not violent enough to expel more gas than is falling in, mass will accumulate onto the white dwarf star until it passes its Chandrasekhar limit. At that point, a foreground cave may provide little protection, as the entire white dwarf star will explode in a tremendous supernova. via NASA http://ift.tt/1B1UAHV

The views of #GreatSmoky Mountains #NationalPark's stunning vistas are breathtaking. #Sunrise photo from Newfound Gap by Dee Langevin (http://ift.tt/18oFfjl). by usinterior

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The Windmill s Moon The Windmill s Moon

Seen from the Canary Island of Fuerteventura, this bright Full Moon rose at sunset. Reaching its full phase on the night of January 4/5, it was the first Full Moon of the new year and the first to follow December's solstice. Of course, in North America the first Full Moon of January has been known as the Wolf's Moon. But this Full Moon, posed in the twilight above an island of strong winds and traditional windmills, suggests another name. The telephoto image, taken at a distance from the foreground windmill, creates the dramatic comparison in apparent size for windmill and Full Moon. via NASA http://ift.tt/1BR6dPH

The stars circle around the North Star on a cold #winter evening in #CraterLake #NationalPark in #Oregon. Michael Bonocore (@michaelbonocore) captured the movement of #stars in the night sky -- called star trails -- by combining 400 separate images. Photo courtesy of @michaelbonocore. by usinterior

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In the Arms of NGC 1097 In the Arms of NGC 1097

Spiral galaxy NGC 1097 shines in southern skies, about 45 million light-years away in the chemical constellation Fornax. Its blue spiral arms are mottled with pinkish star forming regions in this colorful galaxy portrait. They seem to have wrapped around a small companion galaxy below and left of center, about 40,000 light-years from the spiral's luminous core. That's not NGC 1097's only peculiar feature, though. The very deep exposure hints of faint, mysterious jets, most easily seen to extend well beyond the bluish arms toward the left. In fact, four faint jets are ultimately recognized in optical images of NGC 1097. The jets trace an X centered on the galaxy's nucleus, but probably don't originate there. Instead, they could be fossil star streams, trails left over from the capture and disruption of a much smaller galaxy in the large spiral's ancient past. A Seyfert galaxy, NGC 1097's nucleus also harbors a supermassive black hole. via NASA http://ift.tt/1sbkzKX

#DelicateArch glows during #sunset at Arches #NationalPark in #Utah. @ArchesNPS is home to more than 2,000 natural stone arches -- in addition to hundreds of soaring pinnacles, massive fins and giant balanced rocks -- that are unlike any other in the world. Photo by Dvir Barkay (http://ift.tt/18oFfjl). For more great photos of #Arches National Park, follow @ArchesNPS. by usinterior

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A gorgeous shot of first light over Long Pine Key Lake at the Everglades #NationalPark in #Florida. The largest subtropical wilderness in the U.S., the #Everglades is known for its unique mangrove forests. This week, Secretary of the Interior Sally Jewell is visiting the Everglades to see the progress in restoring historic water flows as well as new challenges such as invasive species that threaten the park's ecosystem. Photo by Glenn Nagel (http://ift.tt/18oFfjl). by usinterior

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Stars and Dust in Corona Australis Stars and Dust in Corona Australis

Cosmic dust clouds and young, energetic stars inhabit this telescopic vista, less than 500 light-years away toward the northern boundary of Corona Australis, the Southern Crown. The dust clouds effectively block light from more distant background stars in the Milky Way. But the striking complex of reflection nebulae cataloged as NGC 6726, 6727, and IC 4812 produce a characteristic blue color as light from the region's young hot stars is reflected by the cosmic dust. The dust also obscures from view stars still in the process of formation. At the left, smaller yellowish nebula NGC 6729 bends around young variable star R Coronae Australis. Just below it, glowing arcs and loops shocked by outflows from embedded newborn stars are identified as Herbig-Haro objects. On the sky this field of view spans about 1 degree. That corresponds to almost 9 light-years at the estimated distance of the nearby star forming region. via NASA http://ift.tt/1w2ZSwf

A gorgeous shot of #Zion National Park (@zionnps) in #Utah. Samantha Pickertts (@ravenreviews) took this photo at the park's Canyon Junction overlooking the Virgin River during #sunset. Want to be featured on @USInterior’s Instagram account and our other social media channels? Tag us in your amazing images of #nationalparks, #wildliferefuges (@usfws) or @mypubliclands, and we could end up sharing your photo of America’s public lands! by usinterior

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If you like snow, you'll love #MountRainier #NationalPark in #Washington during #winter. The park, on average, receives about 641 inches of #snow each year, which means there's usually plenty of snow for snowshoeing, skiing, camping, sliding and more. Ed Cooper (@ed_cooper_photography) captured this stunning shot of a #sunburst seen through snow-laden trees at the park's Paradise area with Pinnacle Peak in the background. Photo courtesy of @ed_cooper_photography. by usinterior

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