Dwarf planets of the Solar System.
It is in orbit around the Sun.
It has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape.
It has not cleared the neighborhood around its orbit.
It is not a satellite.
This definition of a dwarf planet was adopted by astronomers at a meeting of the International Astronomical Union (IAU) in Prague on August 24, 2006. The prototype dwarf planet is Pluto. Two other objects, Ceres and Eris (formerly known as 2003 UB313), were also included in the initial dwarf planet catalog. Since then two more members have joined the club: Haumea (formerly known as 2003 EL61) and Makemake (2005 FY9).