iau0807 — Press Release

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17 September 2008, Paris
IAU names fifth dwarf planet Haumea

The International Astronomical Union (the IAU) today announced that the object previously known as 2003 EL61 is to be classified as the fifth dwarf planet in the Solar System and named Haumea.

The decision was made after discussions by members of the International Astronomical Union's Committee on Small Body Nomenclature (CSBN) and the IAU Working Group for Planetary System Nomenclature (WGPSN). This now means that the family of dwarf planets in the Solar System is up to five. They are now Ceres, Pluto, Haumea, Eris and Makemake.

The discovery of Haumea was announced in mid-2005, and the object was initially given the provisional designation of 2003 EL61. It is a bizarre object with a shape resembling a plump cigar. Its diameter is approximately the same as that of the dwarf planet Pluto; however, its odd shape means that it is much thinner. It is also known to be spinning very fast, making one rotation in about four hours. Some have suggested that this rapid rotation could be the reason Haumea came to look as it does - the dwarf planet has been drawn out and elongated by its swift spin.

Haumea sits among the trans-Neptunian objects, a vast ring of distant cold and rocky bodies in the outer Solar System. At this moment it is roughly 50 times the Sun-Earth distance from the Sun, but at its closest the elliptical orbit of Haumea brings it 35 times the Sun-Earth distance from our star.

Haumea is the name of the goddess of childbirth and fertility in Hawaiian mythology. The name is particularly apt as the goddess Haumea also represents the element of stone and observations of Haumea hint that, unusually, the dwarf planet is almost entirely composed of rock with a crust of pure ice.

Hawaiian mythology says that the goddess Haumea's children sprang from different parts of her body. The dwarf planet Haumea has a similar history, as it is joined in its orbit by two satellites that are thought to have been created by impacts with it in the past. During these impacts, parts of Haumea's icy surface were blasted off. The debris from these impacts is then thought to have gone onto form the two moons.

After their discovery, in 2005, the moons were also given provisional designations, but have now too been given names by the CSBN and the WGPSN. The first and largest moon is to be called Hiʻiaka, after the Hawaiian goddess who is said to have been born from the mouth of Haumea and the matron goddess of the island of Hawaiʻi. The second moon of Haumea is named Namaka, a water spirit who is said to have been born from Haumea's body.




The IAU is the international astronomical organisation that brings together almost 10,000 distinguished astronomers from all nations of the world. Its mission is to promote and safeguard the science of astronomy in all its aspects through international cooperation. The IAU also serves as the internationally recognised authority for assigning designations to celestial bodies and the surface features on them. Founded in 1919, the IAU is the world's largest professional body for astronomers.


For more information, please contact:

Lars Lindberg Christensen

IAU Press Officer

ESA/Hubble, Garching, Germany

Tel: +49-89-32-00-63-06

Cell: +49-173-3872-621

E-mail: lars@eso.org




Information about Pluto and the other dwarf planets:

Science paper describing Haumea's physical properties:


IAU website:



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