Rings of Jupiter first time. In 2000, the "Cassini" spacecraft en route to Saturn conducted extensive observations of the Jovian ring system. Future missions to the Jovian system will provide additional information about the rings. Rings of Jupiter The planet Jupiter has a system of rings known as the rings of Jupiter or the Jovian ring system. It was the third ring system to be discovered in the Solar System, after those of Saturn and Uranus. It was first observed in 1979 by the "Voyager 1" space probe and thoroughly investigated in the 1990s by the "Galileo" orbiter. It has also been observed
Definition of planet spherical under its own gravity but not large enough to fuse. This definition would add 19 moons to the list of planets in our Solar System. The discovery since 1992 of extrasolar planets, or planet-sized objects around other stars ( such planets in planetary systems including multiple planetary systems as of ), has widened the debate on the nature of planethood in unexpected ways. Many of these planets are of considerable size, approaching the mass of small stars, while many newly discovered brown dwarfs are, conversely, small enough to be considered planets. The material difference between a low-mass star and