Saturn and its rings, photographed by Voyager 1, 1980.
© National Aeronautics & Space Administration / Science & Society
Saturn was first observed through a telescope by Galileo in 1610, but its rings were not identified until 1659, by Christiaan Huygens. It is a gas giant similar in atmospheric composition to Jupiter, with banded cloud formations. Saturn rotates very quickly, causing it to appear oblate (flattened at the poles). The rings are composed of ice and ice-coated dust and rock. Their origin and formation are not precisely understood, but it seems that tidal effects caused by some of Saturn's moons play a role in maintaining their structure. NASA's two Voyager spacecraft were launched in 1977 to explore the planets in the outer solar system. Voyager 1 flew past Saturn at a height of 124,000 kilometres in November 1980, having previously visited Jupiter.