Illustration of Jupiter and its four Galilean moons; Io, Europa, Ganymede and Callista. Jupiter is the fifth planet from the Sun and the largest in the solar system, with a mass two and a half times that of all the other planets put together. Jupiter's atmosphere consists of colourful, swirling bands of cloud. At centre is the Great Red Spot (GRS), a large storm system that has existed for at least a few hundred years. It consists of cold clouds that rotate anticlockwise several kilometres above the surrounding cloud deck. Jupiter has 80 moons in total. The Galilean moons are the four largest.