This is apparently the qualifications for dwarf planet
From wiki
The resolution describes a dwarf planet as an object that:
* 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 (nearly round) shape
* Has not "cleared the neighbourhood" around its orbit
* Is not a satellite of a planet, or other nonstellar body
This is the qualifier the separates dwarf planets from the standard planets.
* Has not "cleared the neighbourhood" around its orbit
There are a LOT of other bodies around Ceres (Asteroid Belt), Pluto (plutinos and twotino bodies / KBO's), and Eris (Scattered Disk Objects / Kupier Belt Objects
HMMM. What about the rings around Saturn? Those are still in the neighborhood...