Saturday, December 18, 2010

"a phenomenon that has defied explanation"

The striking rings of Saturn are an anomaly in the solar system. While the rings of other planets are dim and composed of nearly equal parts rock and ice, those of Saturn are much brighter and are more than 95% ice, a phenomenon that has defied explanation — until now.

Using sophisticated new computer calculations, planetary scientist Robin M. Canup of the Southwest Research Institute in Boulder, Colo., has shown how the rings could have been formed by the violent destruction of a moon very similar to Saturn's largest remaining moon, Titan.

Gravitational forces from Saturn could have stripped the moon's icy mantle away, scattering the water to form not only the rings but many of the dozens of smaller moons now orbiting the planet, and sucked its rocky core into the body of the planet, Canup postulated in a report published online by the journal Nature.

Canup's idea "offers an attractive solution to the problem that answers several questions at once," wrote Aurelien Crida of the University of Nice-Sophia Antipolis in France and Sebastien Charnoz of Paris Diderot University in an editorial accompanying the paper. The model, they said, "offers, for the first time, a convincing starting point for a consistent theory of the origin of Saturn's rings and satellites."

Planetary scientist Matthew M. Hedman of Cornell University, who was not involved in the research, added, "This makes sense, given what we know about the rings and the history of the outer solar system. It's a fairly complete story of what might have happened."

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