stylistic:tone, structural:expansion, structural:summarization, structural:reformatting, quality:corruption
Geology

Ceres is the largest asteroid in the main asteroid belt. It has been classified as a C ‑ type or carbonaceous asteroid and, due to the presence of clay minerals, as a G-type asteroid. It has a similar, but not identical, composition to that of carbonaceous chondrite meteorites. It is an oblate spheroid, with an equatorial diameter 8% larger than its polar diameter. Measurements from the Dawn spacecraft found a mean diameter of 939.4 km (583.7 mi) and a mass of 9.38 × 10 kg. This gives Ceres a density of 2.16 g/cm, suggesting that a quarter of its mass is water ice.

Ceres makes up 40% of the estimated (2394 ± 5) × 10 kg mass of the asteroid belt, and it has 3 + 1 ⁄ 2 times the mass of the next asteroid, Vesta, but it is only 1.3% the mass of the Moon. It is close to being in hydrostatic equilibrium, but some deviations from an equilibrium shape have yet to be explained. Regardless, Ceres is the only widely accepted dwarf planet with an orbital period less than that of Neptune. Modelling has suggested Ceres's rocky material is partially differentiated, and that it may possess a small core, but the data is also consistent with a mantle of hydrated silicates and no core. Because Dawn lacked a magnetometer, it is not known if Ceres has a magnetic field; it is believed not to. Ceres's internal differentiation may be related to its lack of a natural satellite, as satellites of main belt asteroids are mostly believed to form from collisional disruption, creating an undifferentiated, rubble pile structure.