The region within a planet's magnetic field where charged particles accumulate. The region near a planet where tidal stretching forces overcome a moon's own gravity. The region around a planet where large moons can form. A region where gravitational resonances can occur which create gaps in planetary rings. Saturn's rings are composed mainly of hydrogen and helium.
Narrow rings survive around the Jovian planets because the particles want to bunch together.
Astronomers resort mostly to guesswork when trying answer just one of the following questions about planetary rings. The planet Pluto is often compared to Neptune's large moon Triton because their orbits are typical for objects of each type. The size and composition of a typical asteroid is most similar to Mars's moons. Jupiter's moon Io. There was not enough material in this part of the solar nebula to form a planet.