Ceres is the largest object orbiting within the Asteroid Belt located between Mars and Jupiter. Once considered an asteroid, Ceres has since been upgraded to a Dwarf Planet. Ceres is currently the smallest known dwarf planet, and the only one located within the main Asteroid Belt.

Observations of Ceres gathered with the Hubble Space Telescope revealed that the dwarf planet's composition was much more complex than any other object in the Asteroid Belt. Most interesting was the discovery that Ceres' surface consists of frozen water and Ammonia, both in significant quantities.The Planetary Society: Space Topics - Asteroids and Comets

On September 27, 2007, NASA launched the Dawn Mission sent a probe out into the Asteroid Belt. The spacecraft, named Dawn, will explore both Ceres and the asteroid Vesta in close detail.