This decision led to the demotion of Pluto from a planet to a dwarf planet.
The new definition required a celestial body to meet three criteria:
1. Orbit the Sun.
2. Have sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape.
3. Have cleared the neighborhood around its orbit.
Pluto failed to meet the third criterion, as its orbit is shared with other icy bodies in the Kuiper Belt.
