To don icy rings, don't be too dense

摘要

It's a new spin on things. Saturn's rings might be the result of the planet eating a rotating icy rock. We think rings form when objects such as asteroids or comets pass too close to a planet and are pulverised by its gravity. But that fails to explain why Saturn's rings are mostly water ice while other gas giants have rocky rings. 'The origin of Saturn's rings remains elusive," says Ryuki Hyodo at Kobe University in Japan.