cerus

Ceres is the largest object in the asteroid belt, located between the orbits of Mars and Jupiter. It is also the only dwarf planet in the inner solar system. Ceres was discovered by Giuseppe Piazzi on January 1, 1801, and was initially classified as a planet. However, as more objects were discovered in the asteroid belt, Ceres was reclassified as an asteroid. In 2006, the International Astronomical Union (IAU) reclassified Ceres as a dwarf planet, along with Pluto and Eris.

Ceres is approximately 940 kilometers (585 miles) in diameter and has a mass of about 9.4 x 10^20 kilograms. It is composed of rock and ice, with a differentiated interior that includes a rocky core, an icy mantle, and a thin crust. The surface of Ceres is relatively smooth and shows evidence of past geological activity, such as cryovolcanism. There are also several bright spots on the surface, which are thought to be deposits of salt or other minerals.

Ceres is the only dwarf planet in the inner solar system, and it is the only object in the asteroid belt that is massive enough to be rounded by its own gravity. It is also the only dwarf planet that has been visited by a spacecraft, with NASA's Dawn mission orbiting Ceres from 2015 to 2018. The mission provided valuable data about Ceres's composition, geology, and internal structure, revealing that it has a significant amount of water ice beneath its surface.