Show Summary Details

Quick Reference

The first asteroid to be discovered, by G. Piazzi on 1801 January 1, and hence given the number 1. Ceres is by far the largest asteroid, an oblate spheroid 975 × 909 km, mean diameter 952 km, mass 9 × 1020 kg (about 1% the mass of the Moon) and mean density about 2.0 g/cm3. Its rotation period is 9.075 hours. Ceres contains roughly one-third the mass of the entire asteroid belt. It is a member of the new class of dwarf planets, along with Eris and Pluto. Its mean magnitude at opposition is 7.4; only Vesta can ever become brighter. Its orbit has a semimajor axis of 2.765 AU, period 4.60 years, perihelion 2.55 AU, aphelion 2.98 AU, and inclination 10°.6. Ceres is of G class, with a reflectance spectrum that implies a composition resembling the carbonaceous chondrite meteorites. Ceres is the largest member of a small family of asteroids with a mean distance of 2.76–2.80 AU from the Sun and orbital inclinations of 9–11°. Other Ceres family members include (39) Laetitia, (264) Libussa, (374) Burgundia (all S-class), and (446) Aeternitas (A-class).

Subjects: Astronomy and Astrophysics.

Reference entries

Users without a subscription are not able to see the full content. Please, subscribe or login to access all content.