Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

September 14, 1998
See Explanation.  Clicking on the picture will download 
 the highest resolution version available.

Dust Hip-Deep on Phobos
Credit: Mars Global Surveyor Project, MSSS, JPL, NASA

Explanation: Landing on the Martian Moon Phobos might be harder than previously thought. The reason: Moon dust. Recent photographs of Phobos have indicated that a layer of fine powder estimated to be a meter deep covers the whole surface. Evidence comes from infrared pictures that indicate the rapid speed that Phobos' surface cools after sunset. The above high-resolution picture of Phobos was taken last month by the Mars Global Surveyor spacecraft now orbiting Mars. The larger of two Martian moons, measures about 20 kilometers across, and orbits so close that Mars' gravity should rip it apart in another 50 million years.

Tomorrow's picture: Cosmic Wallpaper

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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)
NASA Technical Rep.: Jay Norris. Specific rights apply.
A service of: LHEA at NASA/ GSFC
&: Michigan Tech. U.