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Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

See Explanation. Clicking on the picture will download the highest resolution version available.

Ceres: Asteroid or Planet?

Explanation: Is Ceres an asteroid or a planet? Although a trivial designation to some, the recent suggestion by the Planet Definition Committee of the International Astronomical Union would have Ceres reclassified from asteroid to planet. A change in taxonomy might lead to more notoriety for the frequently overlooked world. Ceres , at about 1000 kilometers across, is the largest object in the main asteroid belt between Mars and Jupiter. Under the newly proposed criteria , Ceres would qualify as a planet because it is nearly spherical and sufficiently distant from other planets. Pictured above is the best picture yet of Ceres, taken by the Hubble Space Telescope as part of a series of exposures ending in 2004 January. Currently, NASA's Dawn mission is scheduled to launch in 2007 June to explore Ceres and Vesta , regardless of their future designations.

Date August 21, 2006
Credit Credit: NASA , ESA , J. Parker ( SwRI ) et al.
Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
A service of: ASD at NASA / GSFC,
NASA Science Activation & Michigan Tech. U.