Ceres, formally designated 1 Ceres, is the smallest identified dwarf planet in the Solar System and the only one in the asteroid belt. It was discovered on 1 January 1801 by Giuseppe Piazzi, and for half a century it was classified as the eighth planet. It is named after Ceres, the Roman goddess of growing plants, the harvest, and motherly love.
With a diameter of about 950 km (590 mi), Ceres is by far the largest and most massive body in the asteroid belt, and contains almost a third (32%) of the belt's total mass. Observations have revealed that it is spherical, unlike the irregular shapes of smaller bodies with lower gravity. The Cererian surface is probably a mixture of water ice and various hydrated minerals such as carbonates and clays. Ceres appears to be differentiated into a rocky core and ice mantle, and may harbour an ocean of liquid water underneath its surface.From the Earth, Ceres' apparent magnitude ranges from 6.7 to 9.3, and hence at its brightest it is still too dim to be seen with the naked eye. On 27 September 2007, NASA launched the Dawn space probe to explore Vesta (2011–2012) and Ceres (2015).