Saturn’s majestic rings are the remnants of a long-vanished moon that was stripped of its icy outer layer before its rocky heart plunged into the planet, a new theory proposes. The icy fragments would have encircled the solar system’s second largest planet as rings and eventually spalled off small moons of their own that are still there today, says Robin Canup, a planetary scientist at the Southwest Research Institute in Boulder, Colo.
“Not only do you end up with the current ring, but you can also explain the inner ice-rich moons that haven’t been explained before,” she says. Canup’s paper appears online December 12 in Nature.
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