Propelling Evidence: Cassini finds clues to source of Saturn’s rings
By Ron Cowen
Four propeller-shaped gaps in one of Saturn’s main rings are the latest evidence that a shattered moon produced the planet’s dazzling hoops. The discovery supports the theory that a comet or asteroid struck a large, icy Saturn moon about 100 million years ago and that the distributed debris formed rings. They cover a region broader than the distance between the Earth and its moon.
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The 5-kilometer-long gaps turned up in images taken by the Cassini spacecraft on July 1, 2004, as it slipped through the rings before settling into orbit around Saturn. By performing a thorough analysis of faint features in the images, planetary scientists led by Joseph A. Burns and Matthew Tiscareno of Cornell University found the gaps in the bright, mostly homogeneous middle section of Saturn’s A ring.