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There are actually four planets in our Solar System with rings, although some of the ring systems are so faint that they are hard to spot. These planets – Jupiter, Saturn, Uranus, and Neptune – are all gas giants.
Jupiter is the largest planet in our Solar System, but its rings are faint. This is one reason why it was the third planet discovered with rings, even though it is closer to Earth than the other gas giants. Jupiter’s ring system is composed of three main sections. The inner band is known as the halo; the main ring is bright compared to the others, but is a very thin band. The outer band, which is known as the gossamer ring, is composed of two wide rings. Jupiter’s rings are composed of dust, which is believed to come from two of Jupiter’s moons – Amalthea and Thebe. The two gossamer rings are actually named after the moons.
Saturn has the brightest ring system of any planet in our Solar System, which is why it was the first planet with rings discovered. Galileo was the first person to discover Saturn’s rings by using the telescope he had designed. Unfortunately, he could not see them clearly enough to determine what they were. Saturn’s rings are divided into five segments, which listed from the inside out are the C, B, A, F, and G rings. These larger rings are actually divided into thousands of small rings. The rings of Saturn are mostly composed of ice, although there are impurities in them. There are many gaps in the rings of Saturn, two of which are made by moons imbedded in them.
Several astronomers discovered the rings of Uranus in 1977. The famous astronomer William Herschel claimed to have seen the rings over 200 years ago, but many astronomers doubt that was possible because Uranus’ rings are so difficult to see. Uranus’ rings can be divided into 13 separate rings, and there is a varied classification system for the rings that includes Greek letters, numbers, and a combination of English letters and numbers. Uranus’ rings are thought to be composed mostly of water ice with dust and some other particles.
Neptune’s rings were not discovered until almost twenty years ago by the Voyager 2 spacecraft. The rings are so faint that they could not be clearly seen from Earth. Neptune has five separate rings, which are named, starting from the inside ring: Galle, Le Verrier, Lassel, Arago, and Adams. Neptune is the only planet with rings that are named after people, all of them famous astronomers. You may recognize the names Le Verrier and Adams. They were the astronomers who independently predicted the position of Neptune in the sky. The rings, which are red in color, have a lot of dust and are also composed of ice and radiation-processed organic compounds.
Astronomy Cast has a number of articles you will want to listen to including Saturn.