Saturn's Rings

Various theories have tried to explain the existence of Saturn's magnificent ring system. Even the age of the rings has been debated-- some theories hold the rings are essentially as old as the planet, for example, while others argue the rings are a transitory phenomenon which happens to be there at a time humans have telescopes and spacecraft. A new model suggests the rings are indeed old.

The model posits a Titan-sized moon smashed into Saturn perhaps 4.5 billion years ago. As the moon spiraled into the huge planet, Saturn's gravity ripped it apart. The outer, icy layers of the moon stayed in space while the core barreled into Saturn. This could have happened more than once, suggesting an explanation for why Saturn has only one moon of any real heft while Jupiter, for example, has four.

The ice that stayed in space, according to the model, formed the ring system, which originally was made of virtually pure water ice. The model doesn't stop there, however. It goes on to argue ice ripped away from the early big moon(s) eventually formed some of Saturn's small, icy moons, like Tethys, Enceladus, and Mimas. The comprehensive nature of the model no doubt deepens its appeal, but scientists could soon get some hard data to put against the model. Near the end of its mission, in 2017, the Cassini spacecraft will fly directly into the rings, getting the best information yet about their composition, structure, and dynamics.