Ceres
HST image of Ceres
© NASA
It is made of the same rocky minerals as asteroids, but is much larger and rounder. Ceres was discovered way back in 1801 by the Italian astronomer Giuseppe Piazzi, although the image here was taken by the Hubble Space Telescope (HST).
Ceres orbits the Sun every 4.6 years and is about 930 kilometers (580 miles) across - that is about half the size of our own Moon. It seems to have a cratered surface made up of water-bearing minerals, and there are some indications of a very thin atmosphere.
| Facts and Figures | |
| Average Orbit | 414,704,000 km from the Sun or 2.77 AU |
| Orbital Inclination | 10.6 °C |
| Radius | 487 km |
| Mass | 9.4 x 1020 kg or 0.00016 Earths |
| Length of Year | 4.6 Earth years |
| Length of Day | 0.38 Earth days |
| Surface Gravity | 0.003 g |
| Surface Temperature | about -105 °C |
