Close up of Saturn, photographed by Voyager 2, 1981.
© National Aeronautics & Space Administration / Science & Society
This shows the shadow of Saturn's rings on the planet's surface. 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. 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 two Voyager spacecraft were launched by NASA in 1977 to explore the planets in the outer solar system. After first visiting Jupiter, Voyager 2 pased Saturn in August 1981, before continuing on to Uranus and Neptune.