Eris Facts


Eris is the most distant dwarf planet from the Sun and has the greatest mass. Eris is the second largest dwarf planet (very a close second to Pluto) and at one point was considered for the position of the 10th planet. Eris’ discovery promoted discussion that eventually lead to the classification of ‘Dwarf Planets’.

Eris Size

Eris size compared to the Moon and Earth
Eris size compared to the Moon and Earth

Facts about the Dwarf Planet Eris

  • Eris was once considered for the position of tenth planet.
    Eris is the most massive dwarf planet in the Solar System, exceeding Pluto’s mass by 28%. As such, it was a serious contender to be a tenth planet but failed to meet the criteria set out by the International Astronomical Union in 2006.
  • Eris was named after the Greek goddess of discord.
    Fittingly, picking a name for the object took unusually long – more than 1.5 years after its discovery in 2005. Some of the rejected names were Xena, Lila, and Persephone (Pluto’s wife).
  • Eris is the second largest dwarf planet.
    Eris is unquestionably the most massive of the known dwarf planets (the largest object that is not a planet that orbits the Sun) and was once thought to be the largest due to its relative brightness. After a stellar occultation in 2010 its diameter was calculated to be smaller than previously thought and more recent measurement suggested Pluto was larger than thought making it the largest.
  • All the objects in the Asteroid Belt could fit inside Eris.
    Eris is still smaller than the Earth’s Moon, having about two thirds of the Moon’s diameter and one third of its volume.
  • Eris is not always the most distant dwarf planet.
    At Eris’ furthest point from the Sun (Aphelion) it is so distant it is outside the Kuiper Belt, however at its closet point (Perihelion) it is closer the the than Pluto’s most distant point.

Related space facts: