Valles Marineris: The Grand Canyon of Mars


Mars will look good in Earth’s skies over the next few days — but not this good. To get a view this amazing, a spacecraft had to actually visit the red planet. Running across the image center, though, is one the largest canyons in the Solar System. Named Valles Marineris, the grand valley extends over 3,000 kilometers long, spans as much as 600 kilometers across, and delves as much as 8 kilometers deep. By comparison, the Earth’s Grand Canyon in Arizona, USA is 800 kilometers long, 30 kilometers across, and 1.8 kilometers deep. The origin of the Valles Marineris remains unknown, although a leading hypothesis holds that it started as a crack billions of years ago as the planet cooled. Several geologic processes have been identified in the canyon. The featured mosaic was created from over 100 images of Mars taken by Viking Orbiters in the 1970s. Tomorrow, Mars and Earth will pass the closest in 11 years, resulting in the red planet being quite noticeable toward the southeast after sunset.

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Cat s Eye Wide and Deep


The Cat’s Eye Nebula (NGC 6543) is one of the best known planetary nebulae in the sky. Its more familiar outlines are seen in the brighter central region of the nebula in this impressive wide-angle view. But the composite image combines many short and long exposures to also reveal an extremely faint outer halo. At an estimated distance of 3,000 light-years, the faint outer halo is over 5 light-years across. Planetary nebulae have long been appreciated as a final phase in the life of a sun-like star. More recently, some planetary nebulae are found to have halos like this one, likely formed of material shrugged off during earlier episodes in the star’s evolution. While the planetary nebula phase is thought to last for around 10,000 years, astronomers estimate the age of the outer filamentary portions of this halo to be 50,000 to 90,000 years. Visible on the left, some 50 million light-years beyond the watchful planetary nebula, lies spiral galaxy NGC 6552.

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The Great Carina Nebula


A jewel of the southern sky, the Great Carina Nebula, also known as NGC 3372, spans over 300 light-years, one of our galaxy’s largest star forming regions. Like the smaller, more northerly Great Orion Nebula, the Carina Nebula is easily visible to the unaided eye, though at a distance of 7,500 light-years it is some 5 times farther away. This gorgeous telescopic close-up reveals remarkable details of the region’s central glowing filaments of interstellar gas and obscuring cosmic dust clouds. The field of view is over 50 light-years across. The Carina Nebula is home to young, extremely massive stars, including the stars of open cluster Trumpler 14 (below and right of center) and the still enigmatic variable Eta Carinae, a star with well over 100 times the mass of the Sun. Eta Carinae is the brightest star, seen here just above the dusty Keyhole Nebula (NGC 3324). While Eta Carinae itself maybe on the verge of a supernova explosion, X-ray images indicate that the Great Carina Nebula has been a veritable supernova factory.

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IC 5067 in the Pelican Nebula


The prominent ridge of emission featured in this sharp, colorful skyscape is cataloged as IC 5067. Part of a larger emission nebula with a distinctive shape, popularly called The Pelican Nebula, the ridge spans about 10 light-years following the curve of the cosmic pelican’s head and neck. This false-color view also translates the pervasive glow of narrow emission lines from atoms in the nebula to a color palette made popular in Hubble Space Telescope images of star forming regions. Fantastic, dark shapes inhabiting the 1/2 degree wide field are clouds of cool gas and dust sculpted by the winds and radiation from hot, massive stars. Close-ups of some of the sculpted clouds show clear signs of newly forming stars. The Pelican Nebula, itself cataloged as IC 5070, is about 2,000 light-years away. To find it, look northeast of bright star Deneb in the high flying constellation Cygnus.

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NGC 5078 and Friends


This sharp telescopic field of view holds two bright galaxies. Barred spiral NGC 5101 (top right) and nearly edge-on system NGC 5078 are separated on the sky by about 0.5 degrees or about the apparent width of a full moon. Found within the boundaries of the serpentine constellation Hydra, both are estimated to be around 90 million light-years away and similar in size to our own large Milky Way galaxy. In fact, if they both lie at the same distance their projected separation would be only 800,000 light-years or so. That’s easily less than half the distance between the Milky Way and the Andromeda Galaxy. NGC 5078 is interacting with a smaller companion galaxy, cataloged as IC 879, seen just left of the larger galaxy’s bright core. Even more distant background galaxies are scattered around the colorful field. Some are even visible right through the face-on disk of NGC 5101. But the prominent spiky stars are in the foreground, well within our own Milky Way.

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Milky Way Over the Spanish Peaks


That’s not lightning, and it did not strike between those mountains. The diagonal band is actually the central band of our Milky Way Galaxy, while the twin peaks are actually called the Spanish Peaks — but located in Colorado, USA. Although each Spanish peak is composed of a slightly different type of rock, both are approximately 25 million years old. This serene yet spirited image composite was meticulously created by merging a series of images all taken from the same location on one night and early last month. In the first series of exposures, the background sky was built up, with great detail being revealed in the Milky Way dust lanes as well as the large colorful region surrounding the star Rho Ophiuchus just right of center. One sky image, though, was taken using a fogging filter so that brighter stars would appear more spread out and so more prominent. As a bonus, the planets Mars and Saturn are placed right above peaks and make an orange triangle with the bright star Antares. Later that night, after the moonrise, the Moon itself naturally illuminated the snow covered mountain tops.

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Inside a Daya Bay Antineutrino Detector


Why is there more matter than antimatter in the Universe? To better understand this facet of basic physics, energy departments in China and the USA led in the creation of the Daya Bay Reactor Neutrino Experiment. Located under thick rock about 50 kilometers northeast of Hong Kong, China, eight Daya Bay detectors monitor antineutrinos emitted by six nearby nuclear reactors. Featured here, a camera looks along one of the Daya Bay detectors, imaging photon sensors that pick up faint light emitted by antineutrinos interacting with fluids in the detector. Early results indicate an unexpectedly high rate of one type of antineutrino changing into another, a rate which, if confirmed, could imply the existence of a previously undetected type of neutrino as well as impact humanity’s comprehension of fundamental particle reactions that occurred within the first few seconds of the Big Bang.

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LL Orionis: When Cosmic Winds Collide


What created this great arc in space? This arcing, graceful structure is actually a bow shock about half a light-year across, created as the wind from young star LL Orionis collides with the Orion Nebula flow. Adrift in Orion’s stellar nursery and still in its formative years, variable star LL Orionis produces a wind more energetic than the wind from our own middle-aged sun. As the fast stellar wind runs into slow moving gas a shock front is formed, analogous to the bow wave of a boat moving through water or a plane traveling at supersonic speed. The slower gas is flowing away from the Orion Nebula‘s hot central star cluster, the Trapezium, located off the lower right hand edge of the picture. In three dimensions, LL Ori’s wrap-around shock front is shaped like a bowl that appears brightest when viewed along the “bottom” edge. The complex stellar nursery in Orion shows a myriad of similar fluid shapes associated with star formation, including the bow shock surrounding a faint star at the upper right. Part of a mosaic covering the Great Nebula in Orion, this composite color image was recorded in 1995 by the Hubble Space Telescope.

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Milky Way and Planets Near Opposition


In this early May night skyscape, a mountain road near Bursa, Turkey seems to lead toward bright planets Mars and Saturn and the center of our Milky Way Galaxy, a direction nearly opposite the Sun in planet Earth’s sky. The brightest celestial beacon on the scene, Mars, reaches its opposition tonight and Saturn in early June. Both will remain nearly opposite the Sun, up all night and close to Earth for the coming weeks, so the time is right for good telescopic viewing. Mars and Saturn form the tight celestial triangle with red giant star Antares just right of the Milky Way’s central bulge. But tonight the Moon is also at opposition. Easy to see near bright Mars and Saturn, the Full Moon’s light will wash out the central Milky Way’s fainter starlight though, even in dark mountain skies.

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3D Mercury Transit


On May 9, innermost planet Mercury crossed IN FRONT of the Sun. Though pictures project the event in only two dimensions, a remarkable three dimensional perspective on the transit is possible by free viewing this stereo pair. The images were made 23 minutes apart and rotated so that Mercury’s position shifts horizontally between the two. As a result, Mercury’s orbital motion produced an exaggerated parallax simulating binocular vision. Between the two exposures, the appropriately named planet’s speedy 47.4 kilometer per second orbital velocity actually carried it over 65,000 kilometers. Taken first, the left image is intended for the right eye, so a cross-eyed view is needed to see Mercury’s tiny silhouette suspended in the foreground. Try it. Merging the text below the images helps.

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