What are planetary rings made of, and how do they differ among the four jovian planets? Match the terms in the left column to the appropriate blanks in the sentences on the right. Reset Help very eccentric Planetary rings are made up of countless small particles composed of ice and dust equatorial planes of their planets All rings lie in the equatorial planes of their planets Rings' particles have nearly circular orbits. Neptune ice Saturn 's rings are the brightest and widest among jovian planets. Their particles consist most of ice ecliptic plane of the Solar System Jupiter 's rings are mostly dusty and less visible. Saturn nearly circular Uranus and Jupiter both have narrow bright rings diveded by very sparse dusty rings in between. Jupiter dust Neptune 's narrow rings show irregularities in form of brighter arcs, as if the rings were incomplete or partial.