Ceres (also known and desginated as '1 Ceres') is the largest asteroid and the only dwarf planet in the inner Solar System. It is a rock–ice body 950 km (590 mi) in diameter and the smallest identified dwarf planet.
The asteroid was discovered in 1801 by Giuseppe Piazzi. It was the first asteroid to be identified, though it was classified as a planet at the time.
The Cererian surface is probably a mixture of water ice and various hydrated minerals such as carbonates and clays. It appears to be differentiated into a rocky core and icy mantle, and may harbor an ocean of liquid water under its surface. From Earth, the apparent magnitude of Ceres ranges from 6.7 to 9.3, and hence even at its brightest it is still too dim to be seen with the naked eye except under extremely dark skies.
The unmanned Dawn spacecraft, launched on 27 September 2007 by NASA, is expected to be the first to explore Ceres after its scheduled arrival by 2015.