Eris (dwarf planet) facts for kids

The size of Eris compared to Pluto, Makemake, Haumea, Sedna, Orcus, 2007 OR₁₀, Quaoar, and Earth.

Eris and Dysnomia. Eris is the bigger object, Dysnomia is the little circle above it. The Sun is the circle of light to the left.

The orbit of Eris.

Eris is a dwarf planet and a trans-Neptunian object (TNO). It is the second-largest known dwarf planet in the Solar System. Eris is slightly smaller than Pluto, but it is more massive (has more mass) than Pluto. It is a "scattered disc object" in the Kuiper belt, further out than Pluto. It is also called a plutoid because the IAU decided to rename all trans-Neptunian dwarf planets as plutoids. Eris orbits the sun once every 557 Earth years. It has an elliptical orbit, inclined at an angle of 44° between the plane of the orbit of the planet and the ecliptic, the plane containing Earth's orbital path.

Eris has one moon, called Dysnomia.

Discovery

Eris was discovered by Michael E. Brown, Chad Trujillo and David Rabinowitz on January 5, 2005, when they were having a close look at some images of the outer Solar System taken in 2003.

Naming

Eris was originally called Xena, after the main character of the television series Xena: Warrior Princess. However, there is a rule stating that all objects orbiting outside Neptune’s orbit have to be named after a creation of mythology. Therefore, it was officially named Eris on September 13, 2006. Eris is named after the goddess of strife, discord, contention and rivalry in Greek mythology.

Moon of Eris

Eris has one moon called Dysnomia. It was discovered on September 10, 2005. Dysnomia was originally nicknamed Gabrielle, after a character from the television series Xena: Warrior Princess, like Eris. However, like Eris, it could not be called this. Dysnomia was named after the daughter of Eris, in Greek mythology. Dysnomia is the goddess (or spirit) of lawlessness and poor civil constitution.

Classification

Media reports have argued that Eris is the tenth planet, along with astronomers and NASA scientists. However, the definition of a planet was changed in August 2006. Under the new specifications, Eris, along with Pluto, was lowered in status to a dwarf planet.

Future

Scientists are continuing to find out more about Eris and its moon, and to look for any more moons and possible rings. Because Eris is so far away, it would take 24.5 years to visit Eris with a space probe.

Related pages

• Dwarf planet
• Pluto

The Solar System
Sun • Heliosphere	Planets ☾ = moon(s) ∅ = rings		Mercury	Venus	Earth ☾	Mars ☾
			Jupiter ☾ ∅	Saturn ☾ ∅	Uranus ☾ ∅	Neptune ☾ ∅
	Dwarf planets		Ceres	Pluto ☾	Haumea ☾	Makemake
			Eris ☾
	Small Solar System bodies	Asteroids (minor planets)	Groups and families: Vulcanoids · Near-Earth asteroids · Asteroid belt Jupiter Trojans · Centaurs · Neptune Trojans · Asteroid moons · Meteoroids · Pallas · Juno · Vesta · Hygiea · Interamnia · Europa
			See also the list of asteroids.
		Trans- Neptunians	Kuiper belt – Plutinos: Orcus · Ixion – Cubewanos: Varuna · Quaoar · Huya
			Scattered disc: Sedna
		Comets	Periodic comets and non-periodic comets Damocloids · Oort cloud
See also the list of solar system objects

Images for kids

• 

  Animation showing the movement of Eris on the images used to discover it. Eris is indicated by the arrow. The three frames were taken over a period of three hours.

• 

  The distances of Eris and Pluto from the Sun in the next 1,000 years

• 

  Artist's impression of the dwarf planet Eris and its moon Dysnomia. This artistic representation is based on observations made at ESO's La Silla Observatory.

See also

In Spanish: Eris (planeta enano) para niños