The asteroids Ceres, Vesta, and Eros compared to the sizes of Pluto and its moon Charon. Ceres is by far the largest object found within the asteroid belt, and the only object within the region known to be in hydrostatic equilibrium. It is smaller and less massive than Charon. If all of the mass found within the asteroid belt were to be clumped together, it would be roughly twice as massive as Charon.