Ceres (dwarf planet) 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 approximately one-third of the mass of the entire asteroid belt. Ceres is the only object in the asteroid belt known to be rounded by its own
Titan (moon) in diameter, 1.06 times that of the planet Mercury, 1.48 that of the Moon, and 0.40 that of Earth. Before the arrival of "Voyager 1" in 1980, Titan was thought to be slightly larger than Ganymede (diameter ) and thus the largest moon in the Solar System; this was an overestimation caused by Titan's dense, opaque atmosphere, which extends many kilometres above its surface and increases its apparent diameter. Titan's diameter and mass (and thus its density) are similar to those of the Jovian moons Ganymede and Callisto. Based on its bulk density of 1.88 g/cm, Titan's composition is half