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The Eris – A Dwarf Planet

The Eris is the second largest dwarf planet in the solar system. It was discovered on 5th January 2005. It is only largest object in solar System which has not been visited by any space craft. The Eris is the ninth massive body which is orbiting the sun while it is sixteenth most massive body in solar system.

Properties of Eris

  • The Eris was discovered on 5th January 2005 by team of Mike Brown, Chad Trujilo and David Rabinowitz.
  • It was given name after the goddess of strife and discord.
  • Diameter of the Eris is 2326 km.
  • Mass of Eris is 1.66 X 1022 kgs and density is 2.52 gm/cm3.
  • Distance from the sun is 1.441 X 1010 km which is three times that of Pluto.
  • The Eris has only one moon Dysnomia.
  • Eris is slightly smaller than the Pluto but more massive and dense.
  • Orbital period of the Eris around the Sun is 559 years.
  • One day  or one spin on own axis is about 25.9 hours.
  • Maximum distance from the sun (Aphelion) is 97.65 AU and minimum distance from sun (perihelion) is 37.91 AU.
  • Orbital path of Eris is inclined by 44o to elliptic plane and highly eccentric.
  • Due to highly eccentric orbital path temperature on surface varies from -243.2o C to -217.2o C.
  • Eris is visible white in colour.
  • When Pluto was believed as planet, Eris was discovered and it was believed as tenth planet of Solar system.


The Eris is the member of Kuiper belt beyond the orbit of Neptune which is called scattered disk. It was formed along with formation of icy worlds before 4.5 billion years. This icy and rocky object is known as kuiper belt objects or plutoids. Initially it was known as Xena.

Orbit and Rotation

The Eris has longest orbital path and it takes 559 years to complete one revolution around the Sun. As its orbit is highly eccentric, its closest distance (Perihelion) from the Sun is 37.91 AU while farthest distance (Aphelion) from the Sun is 97.65 AU (1AU =1.496 X 108 KM). Last it was on aphelion on 1977 and will reach on perihelion on 2256 to 2258. Its orbital plane is inclined by 44o to elliptic. Average orbital speed of Eris is 3.434 km/s. Axial tilt is 78o.One day on the Eris is 25.9 hours.

Internal Structure, Surface, Atmosphere

It is believed that the Eris is composed of rocky solid core and outer nitrogen rich mantle with frozen methane. No other information regarding internal structure is available at present time.

            The surface of the Eris is similar to that of the Pluto. The surface is made of Nitrogen rich ice with frozen methane. Due to highly eccentricity of orbital path, the temperature on surface varies from -243.2o C to -217.2o C. The surface is highly reflective and bounces back 96 % of light strikes on it which makes the Eris most reflective body in solar system. Its surface is visible bright white due to methane-nitrogen rich icy surface.

            The Eris is about three times far from sun that of the Pluto, but on approaches to closest to the sun, its surface is enough warmer to sublime. During the perihelion frozen nitrogen and methane convert into gaseous and create the form of atmosphere but during aphelion all gaseous condense into snow and ice surface. 


The Eris has only one natural satellite or moon which is known as Dysnomia. It was discovered in 2005 and named after daughter of goddess Eris. Dysnomia is second largest moon of dwarf planet. It is considered to be made of ice and have circular orbit of 16 days.

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Authored by BK Suthar.
This site is about various topics of astronomical and geographical things which present in universe and also surrounding us. It will give you information about various planets, incidents occurs in universe and also about nature.

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