Saturn and its rings, 1980.
© National Aeronautics & Space Administration / Science & Society
This picture was taken from a distance of 13 million kilometres by one of the two Voyager spacecraft launched by NASA in 1977 to explore the planets in the outer solar system. Both flew past Jupiter in 1979 and reached Saturn in late 1980 (Voyager 1) and August 1981 (Voyager 2). The origin and formation of the rings, which are composed of ice and ice-coated dust and rock, are not precisely understood, but it seems that tidal effects caused by some of Saturn's moons play a role in maintaining their structure. The ring system is 250,000 kilometres in diameter, but les than 1 kilometre thick. The gap in the rings is known as the Casini Division, after the astronomer who first observed it. The two bright objects are Tethys and Dione, two of Saturn's moons.