Jupiter. Voyager 1 spacecraft image of the planet Jupiter. This, the largest planet in the solar system, is 318 times heavier than Earth. It is a gas giant with a diameter of 143,000 kilometres. The main components of its atmosphere are hydrogen and helium, with gases such as methane, ammonia and water vapour also present. These trace components are thought to be responible for the colours of the clouds seen in Jupiter's upper layers. The Great Red Spot, a huge storm system, is seen at lower right. This image was taken from a distance of 47 million kilometres on 17th January 1979.