Jupiter's rings are mostly dust particles caught in its gravity. The ring system itself is about 100 m thick. Tidal Forces keep ring particles from forming moons. Roche's Limit for any planet depends on the planet's density and the object's density, but is usually 2-3 planetary radii outward. Observations confirm that all ring systems are within Roche's Limit for their planet.
Shepard moons keep rings orderly.
Perhaps the particles were knocked off the surface of the planet's moons via impacts, or are a disrupted moon. As we discussed previously, some terrestrial planets lack atmospheres because they were too small . Bigger planets have more gravity associated with them, and are better able to keep the lighter gases from drifting away into space. The lighter the molecule, the higher its speed. Thus, giant planets will hold H 2 and other light gases much better than smaller planets like the Earth.