Eris (dwarf planet)

File:Eris and Dysnomia art.png

Eris and Dysnomia. Eris is the bright object in the center. Dysnomia is the little dot to its left.

File:Eris Orbit.svg

The orbit of Eris.

Eris (symbol ⯰) 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 has more mass than Pluto, making it the most massive dwarf planet.

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 planet 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.

When it was first discovered, scientists nicknamed Eris by the name “Xena”.

Eris has one smaller moon, called Dysnomia, that is the second largest moon of a dwarf planet.

Eris was observed by the New Horizons spacecraft in May 2020, as part of its mission following its Pluto flyby in 2015.

Discovery

136199 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

136199 Eris was originally called Xena, after the main character of the television series Xena: Warrior Princess. Due to complications, it was officially named 136199 Eris on September 13, 2006. Eris is named after the goddess of strife, discord, ⁣ contention and rivalry in Greek mythology.

Moon of 136199 Eris

136199 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 136199 Eris. However, like 136199 Eris, it was renamed to Dysnomia due to complications. Dysnomia was named after the daughter of 136199 Eris, in Greek mythology. Dysnomia is the goddess (or spirit) of lawlessness and poor civil constitution.

Classification

Media reports have argued that 136199 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, 136199 Eris, along with 134340 Pluto, was lowered in status to a dwarf planet.

Future

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

Eris (dwarf Planet) Media

• Animation showing movement of 2003 UB313-2-.gif

  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.

• Eris symbol (fixed width).svg

  U+2BF0 ⯰: Planetary symbol for Eris, 0.8px lines. It's common in astrology and has been used by NASA.[1]

• Circled K (all rights reversed).svg

  Circled K (all rights reversed)

• Eris symbol (fixed width).svg

  U+2BF0 ⯰: Planetary symbol for Eris, 0.8px lines. It's common in astrology and has been used by NASA.[1]

• Eris arrow symbol (fixed width).svg

  Eris arrow symbol (fixed width)

• TNOs-wideview-inclination.svg

  Distribution of inclination and semi-major axis of trans-Neptunian objects, showing Eris with a high inclination among the scattered disc objects in grey and purple.

• Eris skypath 1940-2060.png

  Seen from Earth, Eris makes small loops in the sky through the constellation of Cetus.

• Eris800yearsb.gif

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

Related pages

• Dwarf planet
• Pluto