The International Astronomical Union (IAU), the official scientific body for astronomical nomenclature, defines a "dwarf planet" as a celestial body within the Solar System that satisfies these four conditions:
* is in orbit around the Sun
* has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (near-spherical) shape
* has not cleared the neighbourhood around its orbit
* is not a satellite
Three dwarf planets are currently recognized: Ceres, Pluto and Eris.
