A dwarf planet that ignited the fiercest row in decades among the world's astronomers has been appropriately named Eris, after the goddess of discord who sparked the Trojan War.

The object, previous known as 2003 UB313, was spotted in January 2005 by a team of Californian astronomers, whose leader, Michael Brown, proposed the name, the Paris-based International Astronomical Union (IAU) said in a press release on Friday.

About the same size as Pluto and likewise inhabiting the Kuiper Belt, a region beyond the orbit of Neptune, 2003 UB313 staked a claim on being the Solar System's 10th planet.

But that claim was rejected by the IAU last month, which ruled that large objects in this region were "dwarf planets" that were too small to be considered fully-fledged planets.

That definition meant that little Pluto lost its 76-year status as the ninth and outermost planet of the Solar System — a decision that outraged a large number of astronomers, who are campaigning furiously for a review.

Pluto and Eris, together with the large asteroid Ceres, are the forerunners of IAU's new "dwarf planet" category, whose numbers are expectedly to grow rapidly as astronomers, using bigger and better telescopes, identify more and more objects in the Kuiper Belt.

In Greek legends, Eris stirs up jealousy and envy to cause fighting and anger among men.

At the wedding of Peleus and Thetis, the parents of the Greek hero Achilles, all the gods with the exception of Eris were invited.

Enraged at her exclusion, she spitefully caused a quarrel among the goddesses that led to the Trojan War.

Her name is pronounced "ee-ris", the IAU said, adding without apparent irony that the monicker was accepted "almost unanimously" by two committees that oversee the nomenclature of heavenly objects.

Under the IAU listing, Eris is officially designated (136199) Eris. It has a moon, (136199) Eris I, which has been named Dysnomia. In Greek mythology, Eris had two daughters, Dysnomia, a willful spirit of lawlessness, and Eunomia, a peaceable character who puts an end to strife.

Until Eris was officially named, 2003 UB313 was dubbed Xena, after TV's warrior princess, of which Brown is a fan.

According to measurements by the orbiting Hubble telescope, Eris has a diameter of 2,400 kilometers (1,500 miles), making it slightly larger than Pluto.

Campaigners for Pluto say the IAU ruling, made by a vote at a conference in Prague, was unscientific and undemocratic.

Pluto's status had long been contested by astronomers who said its tiny size, odd orbit and orbital plane precluded it from joining the other acknowledged planets.

They also argued that, if Pluto was accepted, the way was open for a vast expansion of the planetary list as more Kuiper Belt objects were uncovered, and this would be confusing for the public.

By the new IAU yardstick, a planet has "cleared the neighbourhood around its orbit" — in other words, it is massive enough to wield a gravity that clears rocks and other debris on its orbital path.

The eight planets recognised by the IAU are Mercury, Earth, Venus, Mars, Jupiter, Saturn, Uranus and Neptune.

IAU Names Dwarf Planet Eris

Garching, Germany (SPX) Sep 15 – The International Astronomical Union announces the names (136199) Eris for the dwarf planet provisionally named 2003 UB 313 and Dysnomia for its moon. The dwarf planet formerly known as 2003 UB 313 received the official designation (136199) Eris, or Eris in short, from the International Astronomical Union on 13 th September 2006. The name was accepted almost unanimously by the Working Group for Planetary System Nomenclature (WGPSN) and the Committee for Small Body Nomenclature (CSBN).

Eris is the second dwarf planet in a sub category of objects of which Pluto is the prototype. The name Eris was proposed by one of the discoverers, Michael Brown ( Caltech, USA). (136199) Eris was discovered on 5 th January 2005 by M. E. Brown, C. A. Trujillo, and D. Rabinowitz at the Palomar Observatory.

Eris is a the Greek goddess of discord and strife. She stirs up jealousy and envy to cause fighting and anger among men. At the wedding of Peleus and Thetis, the parents of the Greek hero Achilles, all the gods with the exception of Eris were invited, and, enraged at her exclusion, she spitefully caused a quarrel among the goddesses that led to the Trojan war.

Eris is pronounced ee'-ris (see link 4).

Eris' moon, formerly known as S/2005 (2003 UB 313) 1 and now known technically as (136199) Eris I, has been named Dysnomia.

Dysnomia is the Daimon spirit of lawlessness. She is the daughter of Eris, goddess of chaos and strife, and the counterpart to Eunomia who puts an end to the anger of grievous strife.

The name Dysnomia was accepted unanimously by the members of the WGPSN.

The name was proposed by Mike Brown, a member of the discovery team.

The new designations have been approved by the IAU Division III Organizing Committee and by the IAU Officers and have been announced in IAU Circular 8747 13 September 2006.

Source: Agence France-Presse