A type of planet, distinct from a classical
planet, which satisfies the following criteria:
This definition of a dwarf planet was adopted by astronomers at a meeting
of the International Astronomical Union (IAU) in Prague on Aug. 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).
- 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.
PLANETS AND SUBSTELLAR OBJECTS