Ceres

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.

Fast Facts

1. Discovered: January 1, 1801
2. Discovered by Giuseppe Piazzi
3. Named after the Roman goddess of growing plants, the harvest, and motherly love
4. Diameter: 932 to 960 kilometers
5. Mass: 8.7x10²⁰ kilograms
6. Orbits the Sun in 4.6 of Earth's years
7. Both the first and largest asteroid ever discovered
8. Contains about a third of the total mass in the Asteroid Belt¹
9. Next largest object, the asteroid Vesta, only contains a tenth of the total mass
10. Outer layer contains significant amounts of ice²

Unique Composition

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.²

Exploration Plans

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.

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