A Dark Dune Field in Proctor Crater on Mars November 28, 2010Posted by John Tintle (MtO deadbait) in Planets.
Tags: HiRISE, Mars, Mars Reconnaissance Orbiter (MRO), NASA, Proctor Crater, University of Arizona
Was this image taken with a telescope or a microscope? Perhaps this clue will help: if the dark forms were bacteria, they would each span over football field across. What is actually being seen are large sand dunes on the floor of Proctor Crater on Mars. The above picture was taken by HiRISE camera on board the Mars Reconnaissance Orbiter (MRO), a robot spacecraft currently in orbit around Mars. The dark rippled dunes likely formed more recently than the lighter rock forms they appear to cover, and are thought to slowly shift in response to pervasive winds. The dunes arise from a complex relationship between the sandy surface and high winds on Mars. Similar dunes were first seen in Proctor Crater by Mariner 9 more than 35 years ago.
Flame Nebula Close-Up November 28, 2010Posted by John Tintle (MtO deadbait) in Deep Space.
Tags: Adam Block, APoD, Flame Nebula, Mount Lemmon SkyCenter, NASA, NGC 2024, University of Arizona
Image Credit & Copyright:
Of course, the Flame Nebula is not on fire. Also known as NGC 2024, the nebula’s suggestive reddish color is due to the glow of hydrogen atoms at the edge of the giant Orion molecular cloud complex some 1,500 light-years away. The hydrogen atoms have been ionized, or stripped of their electrons, and glow as the atoms and electrons recombine. But what ionizes the hydrogen atoms? In this close-up view, the central dark lane of absorbing interstellar dust stands out in silhouette against the hydrogen glow and actually hides the true source of the Flame Nebula’s energy from optical telescopes. Behind the dark lane lies a cluster of hot, young stars, seen at infrared wavelengths through the obscuring dust. A young, massive star in that cluster is the likely source of energetic ultraviolet radiation that ionizes the hydrogen gas in the Flame Nebula.