Natural satellite been directly observed, have been called "moonlets". Small asteroid moons (natural satellites of asteroids), such as Dactyl, have also been called moonlets. The upper limit is also vague. Two orbiting bodies are sometimes described as a double planet rather than primary and satellite. Asteroids such as 90 Antiope are considered double asteroids, but they have not forced a clear definition of what constitutes a moon. Some authors consider the Pluto–Charon system to be a double (dwarf) planet. The most common dividing line on what is considered a moon rests upon whether the barycentre is below the surface of the larger
Ceres (dwarf planet) quadrangles. They are named after the first craters whose names the IAU approved in July 2015. The map image(s) were taken by the "Dawn" space probe. Ceres (dwarf planet) Ceres (; minor-planet designation: 1 Ceres) is the largest object in the asteroid belt that lies between the orbits of Mars and Jupiter, slightly closer to Mars' orbit. With a diameter of , Ceres is the largest of the minor planets, and the only dwarf planet, inside Neptune's orbit. It is the 33rd-largest known body in the Solar System. Ceres is composed of rock and ice and is estimated to comprise