A dwarf planet orbiting beyond Neptune has been designated the third plutoid in the solar system and given the name Makemake, the International Astronomical Union said on Saturday.

The red methane-covered dwarf planet formerly known as 2005 FY9 or "Easterbunny" is named after a Polynesian creator of humanity and god of fertility.

Just last month the IAU, which names planets and other heavenly bodies, decided to create a new class of sub-planets called plutoids.

Pluto, demoted from planet status, and Eris are the other two plutoids. A fourth dwarf planet named Ceres has been excluded from the plutoid club because it orbits in the asteroid belt between Mars and Jupiter. Makemake is just slightly smaller and dimmer than Pluto and was only discovered in 2005.

"The orbit is not particularly strange, but the object itself is big, probably about two-thirds the size of Pluto," said Mike Brown of the California Institute of Technology, who discovered and named Makemake (pronounced MAH-keh MAH-keh).

It was the discovery of these trans-Neptunian objects that led the IAU to re-designate just what it meant to be a planet.

Brown said the name came to him when he was looking for a mythological god and thought of the South Pacific's Easter Island. Makemake was the chief god among people who settled the island.