‘Transit of Rhea Across Saturn’ 2007 Science Photo Library Print by Science Photo Library Archive

Rhea is Saturn’s second largest moon, with a diameter of 1,528 kilometres. It is composed mainly of water ice with a denser rocky core. Part of Saturn’s rings are seen at top right. The rings consist of particles of nearly pure water ice and meteoric dust, and span almost 300,000 kilometres. This image was taken on February 4th 2007 with Cassini’s wide angle camera, at a distance of 1.2 million kilometres from Saturn and 679,000 kilometres from Rhea. (Photo by Science Photo Library)