Saturns rings were discovered in the early 1600s by the Italian astronomer Galileo. Galileo could not see the rings clearly with his small telescope, and thought they were large satellites. In 1656, after using a more powerful telescope, Christiaan Huygens, a Dutch astronomer, described a thin, flat ring around Saturn. Huygens thought the ring was a solid sheet of some material. In 1675, Giovanni Domenico Cassini, an Italian-born French astronomer, announced the discovery of two separate rings made up of swarms of satellites. Later observations of Saturn resulted in the discovery of more rings. The ringlets were discovered in 1980.
Satellites
In addition to its rings, Saturn has 25 satellites that measure at least 6 miles in diameter, and several smaller satellites. The largest of Saturns satellites, Titan, has a diameter of about 3,200 miles -- larger than the planets Mercury and Pluto. Titan is one of the few satellites in the solar system known to have an atmosphere. Its atmosphere consists largely of nitrogen.
Many of Saturns satellites have large craters. For example, Mimas has a crater that covers about one-third the diameter of the satellite. Another satellite, Iapetus, has a bright side and a dark side. The bright side of this satellite reflects about 10 times as much sunlight as the dark side. The satellite Hyperion is shaped somewhat like a squat cylinder rather than like a sphere. Unlike Saturns other satellites, Hyperions axis does not point toward the planet.
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