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Learn about planets outside our solar system through Exoplanets and Alien Solar Systems by Tahir Yaqoob, Ph.D., a book in our online store book collection.
This picture of the asteroid Ceres was made by the Hubble Space Telescope in December 2003 and January 2004. Ceres was declared a "dwarf planet", along with Pluto and Eris, in 2006.
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Image courtesy of NASA, ESA, J. Parker (Southwest Research Institute), P. Thomas (Cornell University), L. McFadden (University of Maryland, College Park), and M. Mutchler and Z. Levay (STScI).

Ceres: Asteroid and Dwarf Planet

Ceres is the largest asteroid in the main asteroid belt. It was classified as a "dwarf planet" in 2006, along with Pluto and Eris. Ceres was discovered on January 1, 1801 by the Italian astronomer and monk Giuseppe Piazzi.

Ceres has a diameter of about 975 km (605 miles). It is by far the largest and most massive body in the main asteroid belt, and contains about a third of the belt's total mass. Ceres orbits the Sun once every 4.6 years. Its orbit lies between the orbits of Mars and Jupiter. The asteroid turns on its axis once every 9 hours, so that's how long a day is on Ceres.

Last modified November 28, 2007 by Randy Russell.

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Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part by the National Science Foundation and NASA, our Founding Partners (the American Geophysical Union and American Geosciences Institute) as well as through Institutional, Contributing, and Affiliate Partners, individual memberships and generous donors. Thank you for your support! NASA AGU AGI NSF