Whirling around the planet Saturn are untold numbers of tiny particles of ammonia ice, dust, and other particles, which, because of the gravitational effects of both Saturn and its moons, have formed themselves into a system of beautiful, thin, concentric rings surrounding the planet on one plane. This spectacular natural feature was thought to be unique to the solar system, but modern observations have shown that rings exist around Jupiter, Uranus, and Neptune as well. The origin of the rings is obscure. It is thought that the rings may have been formed from larger moons that were shattered by impacts of comets and meteors.

Saturn's Rings: Voyager 2 flyby, courtesy JPL