NEWS & EVENTS Ceres Designated a 'Dwarf Planet' 2008 - Members
of the International Astronomical Union (IAU) gathered at the
second General Assembly on August 24, 2006 and voted on an
official definition of planet. A "planet" is defined as a
celestial body that (a) is in orbit around the Sun, (b) has
sufficient mass for its self-gravity to overcome rigid body
forces so that it assumes a hydrostatic equilibrium and (nearly
round) shape, and (c) has cleared the neighborhood around its
orbit. It is the last criterion (C) that eliminates Ceres from
full planet status. The IAU defined a new category of planets
designated as “dwarf planets,” which have the above properties
but reside in a region of the Solar System populated by smaller
objects. The current status of planets in the Solar System is
the eight classical planets (Mercury, Venus, Earth, Mars,
Jupiter, Saturn, Uranus, and Neptune). Pluto, Charon (its moon),
and Ceres are dwarf planets. A dwarf planet is a celestial body
that (a) is in orbit around the Sun