Two years ago the International Astronomical Union (IAU) after a heated debate decided to reclassify Pluto as a dwarf planet, and a trans-Neptunian dwarf-planet altering its original designation as a planet, a designation that Pluto had held since, its discovery in 1930. www.iau2006.org/mirror/www.iau.org/iau0603/index.
Today the IAU announced that it had adopted the term Plutoids to describe Trans-Neptunian celestial objects that meet the definition of dwarf planets adopted two years ago:
Plutoids are celestial bodies in orbit around the Sun at a distance greater than that of Neptune that have sufficient mass for their self-gravity to overcome rigid body forces so that they assume a hydrostatic equilibrium (near-spherical) shape, and that have not cleared the neighbourhood around their orbit. The two known and named plutoids are Pluto and Eris. It is expected that more plutoids will be named as science progresses and new discoveries are made.
http://www.iau.org/public_press/news/release/iau0804/
The current definiton used by the IAU means that only Pluto and Eris are classified as plutoids, excluding Charon, which the IAU holds is merely a satellite of Pluto. Although, there is a minority of astronomers that have adopted the view that Pluto and Charon constitute a double dwarf planet. If this view ultimately prevails they would be the only double planetary system within the solar system
Update a third celestial body has been classified as both a dwarf planet and a Plutoid, it is named Makemake and is found in the Kuiper Belt.
11 June, 2008
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