Pluto -- downgraded two years ago to the status of a dwarf planet -- has an exotically-named chum on the fringes of the Solar System.

The Paris-based International Astronomical Union (IAU) has decided to honour a Kuiper Belt object, 2005 FY9, with the name of Makemake, after the creator of humanity and the god of fertility in the Rapa Nui culture of Easter Island.

Makemake -- pronounced "maki-maki" -- was spotted on March 31 2005 by a trio of astronomers from the Palomar Observatory in southern California.

Under IAU rules, discoverers have the right to name the object. Tradition demands that objects discovered beyond the orbit of Neptune be named after figures in creation mythology.

Lead astronomer Mike Brown of the California Institute of Technology (Caltech) says on his website (http://www.mikebrownsplanets.com/2008/07/whats-in-name-part-2.html) that the team had unofficially called the discovery "Easterbunny" as it was found just after Easter.

Realising that "Easterbunny" didn't quite meet the sobriety expected of a Solar System body, Brown hunted around for a rabbit god in native American lore, of which there are many examples.

"However, they usually have names such as 'Hare' or, better, 'Big Rabbit'," said Brown.

"I spent a while considering 'Manabozho', an Algonquin rabbit trickster god, but I must admit, perhaps superficially, that the 'Bozo' part at the end didn't appeal to me."

Eventually Brown lighted on Makemake, worshipped as a bringer of fertility, because his wife was pregnant with their daughter at the time.

But, he admitted, "Three years is such a long time (to wait for IAU approval) that I think I'm going to have a hard time calling Makemake by its real name."

Wee Pluto, considered a planet for 76 years, was relegated to the Solar System's second division at a stormy meeting of the IAU in August 2006.

A "dwarf planet" is defined as a celestial body orbiting the Sun that is big enough to be rounded by its own gravity but which has not cleared its neighbouring region of debris and is not a satellite.

The group now has four members. Pluto, Makemake and Eris constitute "plutoids," or Pluto-like objects in the Kuiper Belt, a girdle of icy objects beyond the orbit of Neptune. The fourth dwarf planet is Ceres, which inhabits the asteroid belt between Mars and Jupiter.

Dozens more may be added to the category when the Kuiper Belt is more closely scrutinised, astronomers say.