Provisional name
2003 UB313
Dwarf Planet
Discovery date
Discovery chart
Discovery position
20 Aries 00' Rx
Time of announcement
29.07.2005 - 19:33 UT
Orbital period
557.4 years
  • extremely elliptical
  • crosses the orbit of Pluto
  • inclination is 44 degrees
97.518 AU
38.285 AU
Semimajor axis
67.902 AU

Photograph copyright © Susanna Kauppinen. All rights reserved.
Photo: Copyright © Susanna Kauppinen.

Eris is the Greek goddess of strife, who indirectly initiated the Trojan War.

The goddesses Hera, Athena and Aphrodite had been invited along with the rest of Olympus to the wedding of Peleus and Thetis, who would become the parents of Achilles. Eris was furious because she had been dismissed. She therefore tossed into the party the Apple of Discord, a golden apple "To the Fairest One" provoking the goddesses to begin quarreling about the appropriate recipient.

Paris, Prince of Troy, chose to award the apple to Aphrodite, who tempted him with the most beautiful woman in the world: Helen, wife of Menelaus of Sparta. His city was destroyed in the war that ensued.

Greek Mythology Link

Eris and Dysnomia
On September 10th 2005 astronomers discovered that UB313 has a moon. Xena and Gabrielle were nicknames from a TV series. They were not proposed as permanent names of these objects though.

Xena in the television series

On September 13th 2006 IAU approved the names Eris and Dysnomia. IAUC 8747

Image: W.M. Keck Observatory

In Greek mythology Dysnomia is Eris' daughter and the demon spirit of lawlessness.

Dysnomia (disease) is a marked difficulty in remembering names or recalling words needed for oral or written language.

Discovery pictures of 2003 UB313
Image: Samuel Oschin Telescope, Palomar Observatory

"It's a big sucker!" - Mike Brown
"It's not every day that you find something Pluto-sized or larger!" - Chad Trujillo