Saturn's rings. True colour Cassini spacecraft image of a section of Saturn's rings. The image mainly shows the B ring (beige), the outermost of Saturn's inner rings. Saturn's rings are mostly made of particles of water ice, ranging in size from microns to a few metres in diameter. The different colours in the rings reveal the presence of contaminants, such as rock or carbon compounds. This is a composite of images taken by the narrow angle camera on the Cassini spacecraft on 21 June 2004, when Cassini was 6.4 million kilometres from Saturn. Cassini entered Saturn orbit on 30 June 2004 and will spend four years studying the planet, its rings and its moons.