Cassini spacecraft image of Saturn's rings. Saturn's rings consist of particles of nearly pure water ice. Their varying densities are responsible for the varying darkness of the rings. The joint NASA-ESA Cassini-Huygens spacecraft was launched in 1997 and took seven years to reach Saturn and its moons. The Huygens probe separated from Cassini on 25th December 2004, and descended to the surface of Saturn's largest moon, Titan. The Cassini orbiter continued orbiting Saturn; studying its atmosphere and rings and performing flybys of its moons. Image obtained by Cassini's wide-angle camera on 24th September 2016 at an approximate distance of 456,000 kilometres from Saturn.