Telesto, moon of Saturn, Cassini image. The image is a composite of ultraviolet, green and infrared images. The colour variations are thought to show differences in the composition of the surface. Telesto is a Trojan moon. This is a term used for a small satellite that orbits in a region of stability (a Lagrangian point) between the orbits of two more massive bodies. In Telesto's case, the bodies are Saturn itself, and the moon Tethys. It orbits in the L4 point, which is 60 degrees in front of Tethys in its orbital path. Tethys is some 1070 kilometres wide, Telesto just 24 kilometres. Image taken at a distance of 20,000 kilometres on 25th December 2005.