File:Eris_and_moon_Dysnomia_JWST_NIRCam.jpg · Wikimedia Commons · See Wikimedia Commons

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Eris

Also known as Sol k, Eris (dwarf planet), Xena, 136199 Eris

dwarf planet in the Solar System

AI overview

Eris is a small, icy dwarf planet located far out in the Solar System beyond Neptune. It matters because its discovery in 2005 challenged our understanding of what counts as a planet and led astronomers to create the new category of "dwarf planets."

AI-generated from the Wikipedia summary — may contain errors.

Picture of the Day · NASA

Pathfinder on Mars

2026-07-04

On July 4th, 1997, using its own array of fireworks, a parachute, and a cocoon of airbags, the Mars Pathfinder spacecraft bounced like a giant beach ball at least 15 times before it came to rest on the surface of Mars at 10:07 AM Pacific Daylight Time. After its then novel airbag-assisted landing sequence was completed, Pathfinder transmitted this color mosaic to mission operators on Earth. In the scene from another world, the Mars Sojourner robot rover is visible in the foreground, crouched on top of the unfolded Pathfinder. About the size of a large house cat, the six-wheeled, solar-powered Sojourner became the first successful Martian rover. Surrounding Pathfinder are deflated airbags and the rock-strewn terrain of the Ares Vallis floodplain. In the distance Martian hills appear against a dusty brownish sky. The Pathfinder lander was subsequently renamed the Carl Sagan Memorial Station.

via NASA APOD

Wikidata facts

Official name: 136199 Eris
Area: 17000000
Diameter: 2326
Radius: 1163
Mass: 16.6
Orbital period: 557.55
Image: Eris and dysnomia.jpg

Show 23 more facts

Commons category: 136199 Eris
time of discovery or invention: 2003-10-21
provisional designation: 2003 UB313
orbital eccentricity: 0.4346554671925892
orbital inclination: 44.1444
longitude of ascending node: 35.9045
argument of periapsis: 151.6871
albedo: 0.96
apparent magnitude: 18.7
mean anomaly: 205.384
periapsis: 38.013
semi-major axis of an orbit: 67.740
apoapsis: 97.468
density: 2.52
periapsis date (DEPRECATED): 2258-10-14
absolute magnitude: -1.1
rotation period: 25.9
angular diameter: 34.3
temperature: 55
name: Xena
Unicode character: ⯰
IPA transcription: ˈeːʁɪs
surface gravity: 0.82

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Article

Spectral type B−V=0.78, V−R=0.45 Apparent magnitude 18.7 Absolute magnitude (H) –1.26 Angular diameter 34.4±1.4 milli-arcsec

Eris (minor-planet number 136199) is the most massive and second-largest known dwarf planet in the Solar System. It is a trans-Neptunian object (TNO) in the scattered disk and has a high-eccentricity orbit. Eris was discovered in January 2005 by a Palomar Observatory–based team led by Mike Brown and verified later that year. It was named in September 2006 after the Greco–Roman goddess of strife and discord. Eris is the ninth-most massive known object orbiting the Sun and the sixteenth-most massive in the Solar System (counting moons). It is also the largest known object in the Solar System that has not been visited by a spacecraft. Eris has been measured at 2,326 ± 12 kilometres (1,445 ± 7 mi) in diameter; its mass is 0.28% that of the Earth and 27% greater than that of Pluto, although Pluto is slightly larger by volume. Both Eris and Pluto have a surface area that is comparable to that of Russia or South America.