eris

Eris is one of the largest known dwarf planets in our solar system. It's about the same size as Pluto, but is three times farther from the Sun.

Eris first appeared to be larger than Pluto. This triggered a debate in the scientific community that led to the International Astronomical Union's decision in 2006 to clarify the definition of a planet. Pluto, Eris and other similar objects are now classified as dwarf planets.

Originally designated 2003 UB313 (and nicknamed for the television warrior Xena by its discovery team), Eris is named for the ancient Greek goddess of discord and strife. The name fits since Eris remains at the center of a scientific debate about the definition of a planet.