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.

2005 January 24
See Explanation.  Clicking on the picture will download
 the highest resolution version available.

Riverbeds and Lakebeds Discovered on Saturn's Titan
Credit: ESA, NASA, Descent Imager/Spectral Radiometer Team (LPL)

Explanation: Methane rain, evaporating lakes, flowing rivers, and water ice-volcanoes all likely exist on Saturn's moon Titan, according to preliminary analyses of recent images taken by the successful Huygens lander. A snaking and branching riverbed is identified with the dark channel near the top of the above image, while a dark lakebed is identified across the image bottom. Both the riverbed and lakebed were thought to be dry at the time the image was taken but contained a flowing liquid - likely methane - in the recent past. Titan's surface was found to appear strangely similar to Earth even though it is so cold that methane flows and water freezes into rock-hard ice. Although the Huygens probe has now run out of power, the images it returned will likely be studied for decades to come. The Cassini mothership is scheduled to continue to orbit Saturn and return images for several more years.

Tomorrow's picture: fireworks galaxy

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