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Monday, November 23, 2009

Photo: Saturn's "Walnut Moon" Mystery Solved


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Saturn's icy moon Iapetus has long baffled scientists with its unusual walnut shape.

Now a team of researchers says they have an explanation: The satellite's surface froze during its infancy, locking the moon's shape at a time when it was spinning much faster than it is now.

Photograph courtesy NASA/JPL/Space Science Institute