Comet fragments. Artwork of three fragments of a comet passing a ring (lower left) of the gas giant planet Saturn (right). Comets are icy bodies that originate from the outer reaches of the solar system. They trace elongated orbits about the Sun, periodically passing into the planetary regions. The large gravity of the gas giants (like Jupiter and Saturn) can attract and break up these comets. This helps to protect the inner solar system from potentially devastating impacts. This type of event was observed in July 1994, when fragments of the Shoemaker-Levy 9 comet impacted Jupiter. The debris forming Saturn's rings is thought to result from a moon shattered by a large impact.