Pluto and its moons Charon, Hydra and Nix (right) Eris and its moon Dysnomia (left)

Two years after the International Astronomical Union’s (IAU) controversial decision to demote Pluto to the status of dwarf planet, Pluto’s fans have been given a consolation prize.

Meeting in Oslo, Norway on Jun-11 the IAU decided that transneptunian dwarf planets will now be known as plutoids.

The full definition is:

A plutoid is a celestial body in orbit around the Sun at a semi-major axis greater than that of Neptune. It has sufficient mass to be near-spherical in shape, and has not cleared the neighbourhood around its orbit. Satellites of plutoids are not plutoids.

The two known and named plutoids are Pluto (surprise, surprise) and Eris. More are expected to be found further out than Pluto.

The dwarf planet Ceres is not a plutoid as it is located in the asteroid belt between Mars and Jupiter. At present Ceres is thought to be a unique object.

Image credit: IAU

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