Origins Of Saturn's Moonlets

A new study indicates that the tiny moons that orbit just inside and just outside Saturn's ring system were likely "born" in the rings not too long ago. The tiny moons are sometimes called "shepherding" moons because their gravity helps the rings maintain their shape, but the connection may be even deeper. According to computer simulations, the moons may have slowly built up within the rings, acquiring new material from the rings, until at some point the gravitational interplay with Saturn and the mass of the ring system pushed them into their present orbits.

That point may not have been terribly long ago, either. Judging by the lack of cratering on their bright, icy surfaces, they could have been formed as few as 10 million years ago. That would suggest the ring system is a dynamic place, still evolving. That view, in turn, would mesh with the theory that the ring system itself is in fact transitory. We just happen to be around at the right time to be able to see the glorious sight of Saturn ringed.