Saturn's rings. Cassini spacecraft image of Saturn's B ring. The bright spot at lower centre is caused by the angle between the spacecraft, the Sun and the rings being near zero, known as the opposition effect. Study of the opposition effect may help scientists determine the size and spatial distribution of the icy particles that make up the rings. The Cassini-Huygens spacecraft was launched in 1997 to investigate Saturn, its rings and its moons. This image was taken at a distance of 478,000 kilometres from Saturn on 26 June 2005.