CICLOPS: Cassini Imaging Central Laboratory for OPerationS

Dark Side of Dione
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Dark Side of Dione
PIA 05418

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  The icy, cratered surface of Saturn's moon Dione (1,123 kilometers, 698 miles across) shows more than just its sunlit side in these two processed versions of the same image.

The view at left, with only mild enhancement, shows a romantic crescent with large craters visible. The version at right has been greatly contrast enhanced to show the side of Dione lit faintly by reflected light from Saturn. A similar phenomenon can be seen from Earth, when the Moon's dark side is visible due to "earthshine". The crater at the top of the image appears to have a sunlit central peak in the enhanced view - a common characteristic of craters on Dione as seen in Voyager images. Slight variations in brightness on the moon's dark side hint at the bright curvilinear streaks seen by Voyager. These streaks are thought to be deposits of water ice.

The image was taken with the narrow angle camera on July 2, 2004, from a distance of about 1.4 million kilometers (860,000 thousand miles) from Dione and at a Sun-Dione-spacecraft, or phase, angle of about 119 degrees.. The image scale is 8 kilometers (5 miles) per pixel. The images have been magnified by a factor of two to aid visibility.

[Caption updated on October 4, 2005.]

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Office of Space Science, Washington, D.C. The imaging team consists of scientists from the US, England, France, and Germany. The imaging operations center and team lead (Dr. C. Porco) are based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission, visit and the Cassini imaging team home page,

Credit: NASA/JPL/Space Science Institute
Released: July 19, 2004 (PIA 05418)
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