Saturn. Composite image of a computer-enhanced Voyager 2 image of the planet Saturn on a starfield. Saturn is a gas giant planet composed mainly of hydrogen and helium. Traces of gases such as ammonia and methane are also present. Its ring system is mostly made up of millions of orbiting chunks of ice. It is the second largest planet in the solar system (behind Jupiter), and has a diameter of around 120,000 kilometres. It is around 95 times heavier than Earth. This image was taken from a distance of 43 million kilometres on 12th July 1981.