Saturn and Rhea,Cassini image. Saturn,a gas giant planet with an extensive ring system,is over 120,000 kilometres across. This sunlit equatorial view shows Saturn's clouds and the ring system edge-on,as the dark band across centre. The moon Rhea (1528 kilometres across) is at far right. Rhea,the second-largest of Saturn's moons,orbits outside the main ring structures,at a distance of around 470,000 kilometres from the planet's equator. The shadow just seen at far left is from the moon Tethys. This mosaic of images was obtained on 4 November 2009,by the wide-angle camera on the orbiting Cassini spacecraft |