Animation of a crescent Charon and the distant Sun, from the surface of Pluto, a dwarf planet in the Kuiper Belt. Charon is the largest of Pluto's moons, with over half the diameter and an eighth of the mass of the dwarf planet itself. The two bodies are tidally locked to each other, presenting the same face to each other at all times. This means that they do not appear to move in each other's skies. They orbit each other at a distance of some 19,500 kilometres. The similarity in their masses means that they both orbit a point between them. This could see them be classified as binary dwarf planets.