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Dark Dunes on Mars
Image courtesy NASA/JPL/University of Arizona
Dark dunes make waves across the floor of Proctor Crater, a 93-mile-wide (150-kilometer-wide) basin on Mars, as seen in a picture by the HiRSE camera aboard NASA's Mars Reconnaissance Orbiter released April 28.
The dunes are most likely made of fine, basaltic—or volcanic—sand that collected in the bottom of the crater, according to NASA. Patches of frost seem to light up the tops of some dunes, while large boulders dot the smaller ripples along the dune beds.Published May 4, 2010
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Black Hole Middleweights
Image courtesy NASA/CXC/Tsinghua University
Deep inside a cosmic "cigar," astronomers have found two new middleweight contenders: A new picture of M82, aka the Cigar Galaxy, shows a pair of objects that might be so-called intermediate-mass black holes. The image, released April 29, combines x-ray data from NASA's Chandra X-ray Observatory (inset) with optical light captured by the Hubble Space Telescope and infrared light spied by the Spitzer Space Telescope.
It's long been a mystery whether black holes exist that have masses in between those left by dying stars and the supermassive versions at the centers of most galaxies. The two new objects' brightnesses and estimated masses suggest they are both such midsize black holes, and that they narrowly avoided falling into the supermassive black hole thought to be at the heart of M82.Published May 4, 2010
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Sahara Dust Wall
Image courtesy Jeff Schmaltz, MODIS Rapid Response Team, NASA
If you squint, you can just make out Imhotep's face about to swallow Brendan Frasier. Okay, not really. But this dust storm (light tan color), shown straddling the border (superimposed) between Burkina Faso and Niger (with Mali to the north) in late April, does seem worthy of an angry mummy.
NASA's Aqua satellite saw the massive plume spanning hundreds of kilometers over the Sahara and the Sahel, a semiarid grassland on the desert's southern edge. In the region pictured, clearer skies ahead of the billowing dust suggest that the storm is advancing like a wall toward the southeast.Published May 4, 2010
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Martian Slope Streaks
Image courtesy NASA/JPL/University of Arizona
Does the Museum of Modern Art take submissions from robots?
Released on April 29, this picture from NASA's Mars Reconnaissance Orbiter shows three newly "painted" streaks on the wall of a Martian crater. Some of these older, lighter streaks have been visible since 2001, but the darker trio first appeared in a 2007 image.
Although astronomers aren't sure how such streaks form, they think it could be due to dry dust avalanches or even cascades of salty water seeping from underground.Published May 4, 2010
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African Volcanoes
Image courtesy ESA
A trio of volcanoes sits nestled in Tanzania's Great Rift Valley in a composite radar picture released in late April by the European Space Agency. The image combines data from November and December 2009 and February 2010 taken by ESA's Envisat orbiter.
Single radar images don't show color, so the hues in the new picture represent surface changes, such as shifts in vegetation color and amount, over time.Published May 4, 2010
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