Asteroid or miniplanet? Cornell astronomer finds Ceres appears to have shape and interior similar to terrestrial planets

http://www.news.cornell.edu/stories/Sept05/Ceres.to.html

Sept. 15, 2005

By Thomas Oberst
cunews@cornell.edu

ITHACA, N.Y. -- When is a space rock more than just a space rock?

Ceres 1 was already holding the title of the solar system's largest asteroid. Now new observations show the space rock may be more worthy of the appellation "miniplanet."

On Sept. 7 NASA released photographs of Ceres that show the rock is a smooth ellipsoid, or oblong sphere, with an average diameter of approximately 590 miles -- about the size of Texas. A scientific paper on the findings, by a group led by Peter C. Thomas, senior research associate at Cornell University's Center for Radiophysics and Space Research, appeared in the Sept. 9 issue of the journal Nature.

Co-author Joel Parker, an astronomer at the Southwest Research Institute in Boulder, Colo., used the Hubble Space Telescope's Advanced Camera for Surveys to snap 267 images of Ceres on Dec. 28, 2003, during a nine-hour period -- one Ceres "day."