Published in Nature, 9 Jun 2010
For decades, researchers have puzzled over the origin of Saturn’s baby moons. According to conventional models, these moons are so small that collisions with comets should have blown them to pieces long ago. Now a group of researchers in France and Britain think they have the answer — and it lies in the planet’s icy rings.
Accepted theory says that the giant planets, and their moons, slowly accreted out of a gaseous ‘protoplanetary disk’ around the Sun some 4.5 billion years ago. Yet Saturn’s baby moons never quite fitted this picture. At less than 50 kilometres across, they ought to have been destroyed by comets over that period. And over time, moons tend to recede from the planets they orbit, as indeed our Moon is receding from Earth. But Saturn’s moons are in such a close orbit that they would have had to have formed virtually inside the giant planet. […]
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