Herschel Crater CloseupA high-resolution closeup of Saturn's moon Mimas shows mysterious color differences around the huge Herschel crater. The combined picture, released March 29, 2010, is based on several shots taken by NASA's Cassini orbiter during its closest ever flyby of the tiny moon in February.

To the human eye, Mimas would likely be a uniform gray. The colors in this picture are exaggerated, based on data from visible, infrared, ultraviolet, and green filters on Cassini's cameras. The result shows bluish material in and around the 80-mile-wide (128-kilometer-wide) crater contrasted against older, greenish terrain. Astronomers are unsure why these color differences exist.

During the flyby, Cassini also captured the highest-resolution temperature map of Mimas, revealing an unexpected pattern of warm regions reminiscent of the arcade icon Pac-Man.
Image courtesy NASA/JPL/SSI

Space Photos: Giant Crater, Trojan Moon

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Published March 31, 2010