Fourth Dwarf Planet Named For Polynesian God

posted: 20 July 2008 2:51 pm ET

: Artist rendering of the object now called Eris. This image was released when the object was announced July 29, 2005 by Mike Brown of Caltech as 2003 UB313. It is larger than Pluto. The Sun is in the background. Credit: NASA/JPL/Caltech
: The artist's concept gives a view of the Pluto system from the surface of Nix or Hydra, two of its moons discovered in 2005. Nix and Hydra are two to three times farther from Pluto than its large moon, Charon (to the right of Pluto), which was discovered in 1978. Credit: NASA, ESA and G. Bacon (STScI).

A dwarf planet circling the sun out beyond the orbit of Neptune has been rechristened Makemake after a Polynesian god and designated the third of the solar system's new class of plutoids, the International Astronomical Union (IAU) announced Saturday.

Makemake is a small, red-tinged world that ranks among the largest objects in the outer solar system. But it is still smaller and dimmer than the already demoted dwarf planet Pluto, which astronomers reclassified as a plutoid last month.

Astronomers discovered Makemake (pronounced MAH-keh MAH-keh), the fourth dwarf planet so far, in 2005 and believe its surface is covered by a layer of frozen methane. It is bright enough to be seen by a high-end amateur telescope, the IAU said.

"The orbit is not particularly strange, but the object itself is big," said astronomer Mike Brown of the California Institute of Technology in Pasadena, Calif., who led the team that discovered Makemake. "Probably about two-thirds the size of Pluto."

Pluto, Makemake and a third object - dubbed Eris - are all classified as plutoids, as well as dwarf planets. The solar system's largest asteroid Ceres is also a dwarf planet, but not in the plutoid class because its orbit, which falls in the belt of asteroids between Mars and Jupiter, is smaller than that of the more distant Neptune.

Originally designated 2005 FY9, the object was nicknamed "Easterbunny" by its discoverers before officially being named Makemake after the Polynesian creator of humanity and the god of fertility, the IAU said.

"We consider the naming of objects in the solar system very carefully," said Brown.

Makemake's methane ice-rich surface, while fascinating, did not easily relate to Earthly mythology, he added. But the small dwarf planet, like Eris and the object 2003 EL61 also spotted by Brown and his team, was found while his wife was pregnant with their daughter. It was the discovery of those three objects that led to Pluto's drop from full planet to dwarf planet in 2006.

Brown was researching the mythology of Rapa Nui, or Easter Island, in the South Pacific for prospective names when he learned of the creator and fertility god Makemake.

"I am partial to fertility gods," Brown said, recalling the discovery of Makemake, Eris and 2003 EL61. "I have the distinct memory of feeling this fertile abundance pouring out of the entire Universe. Makemake was part of that."