A → dwarf planet which is a
→ trans-Neptunian object (TNO) with an orbital
→ eccentricity of 0.44, an
→ inclination
of 44 degrees and a surface composition very similar to
that of → Pluto. It orbits the Sun as far as twice
Pluto’s distance from the Sun. → Occultation
observations carried out in 2010 were
used to measure the size of Eris accurately. Eris’s newly determined diameter is
2326±12 km. The observations show that Eris is an almost perfect
twin of Pluto in size. They also reveal a
very reflective surface, with an → albedo
of 0.96, suggesting that it is uniformly covered in a thin layer of ice, probably a
frozen atmosphere (Sicardy et al. 2011, Nature 478, 493).
Like Pluto, Eris has a moon, which has been officially named by the
→ International Astronomical Union
as (136199) Eris I (→ Dysnomia).
The informal names of Eris were Xena and 2003 UB313.
See also: Named after Eris the Gk. goddess of chaos and strife. She created a quarrel
among goddesses that led to the Trojan War.
