[meteorite-list] The Dwarf Planet Formerly Known as Xena Has Officially Been Named Eris, IAU Announces

[Ron Baalke]

http://pr.caltech.edu/media/Press_Releases/PR12893.html

Caltech News Release
For Immediate Release
September 14, 2006

The Dwarf Planet Formerly Known as Xena Has Officially Been Named 
Eris, IAU Announces

PASADENA, Calif.--The International Astronomical Union (IAU) today 
announced that the dwarf planet known as Xena since its 2005 
discovery has been named Eris, after the Greek goddess of discord.

Eris's moon will be known as Dysnomia, the demon goddess of 
lawlessness and the daughter of Eris.

The names are those suggested by the discoverers of the dwarf 
planet--Mike Brown, a professor of planetary astronomy at the 
California Institute of Technology, Chad Trujillo of the Gemini 
Observatory, and David Rabinowitz of Yale University, and by the 
discoverers of the moon--Brown and the engineering team of Keck 
Observatory where the observations were made.

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

"She's quite a fun goddess, really," Brown adds. "And, for the Xena 
fans out there who are sad to see the name go, Eris appeared in her 
Latin version of Discordia as a recurring character on Xena: Warrior 
Princess."

True to its name, the dwarf planet Eris has stirred up a great deal 
of trouble among the international astronomical community, most 
recently last month when the question of its proper designation led 
to a raucous meeting of the IAU in Prague. At the end of the 
conference, IAU members voted to demote Pluto to dwarf-planet status, 
leaving the solar system with eight planets.

However, the ruling effectively settled the year-long controversy 
about whether Eris would rise to planetary status. Somewhat larger 
than Pluto, the body was formally announced to the world on July 29, 
2005. With the August IAU ruling, Eris is the largest dwarf planet.

Eris, about 2,400 kilometers in diameter, was discovered on January 
8, 2005, at Palomar Observatory with the NASA-funded 48-inch Samuel 
Oschin Telescope. A Kuiper-belt object like Pluto, but slightly less 
reddish-yellow, Eris is currently visible in the constellation Cetus 
to anyone with a top-quality amateur telescope.

Eris is now about 97 astronomical units from the sun (an astronomical 
unit is the distance between the sun and Earth), which means that it 
is some nine billion miles away at present. On a highly elliptical 
560-year orbit, Eris sweeps in as close to the sun as 38 astronomical 
units. At present, however, it is nearly as far away as it ever gets.

Pluto's own elliptical orbit takes it as far away as 50 astronomical 
units from the sun during its 250-year revolution. This means that 
Eris is sometimes much closer to Earth than Pluto--although never 
closer than Neptune.

Dysnomia, the only satellite of Eris discovered so far, is about 250 
kilometers in diameter and reflects only about 1 percent of the 
sunlight that its parent reflects. The name is both a nod to Lucy 
Lawless, the actress who played Xena on the TV show, and to the 
astronomical tradition of naming the first satellites of dwarf 
planets.

Based on spectral data, the researchers think Eris is covered with a 
layer of methane that has seeped from the interior and frozen on the 
surface. As in the case of Pluto, the methane has undergone chemical 
transformations, probably due to the faint solar radiation, causing 
the methane layer to redden. But the methane surface on Eris is 
somewhat more yellowish than the reddish-yellow surface of Pluto, 
perhaps because Eris is farther from the sun.

Brown, Trujillo, and Rabinowitz first photographed Eris with the 
Samuel Oschin Telescope on October 31, 2003. However, the object was 
so far away that its motion was not detected until they reanalyzed 
the data in January of 2005.

The search for new planets and other bodies in the Kuiper belt is 
funded by Caltech and NASA. For more information on the program, see 
the Samuel Oschin Telescope's website at 
http://www.astro.caltech.edu/palomarnew/sot.html.

For more information on Mike Brown's research, see 
http://www.gps.caltech.edu/~mbrown .

To learn more about Eris, see
http://www.planeteris.com .

Contact:     Robert Tindol
                (626) 395-3631
                tindol at caltech.edu