Al hail Eris!


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Eris (mythology)

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Eris
Eris on an Attic plate, ca. 575-525 BC
Eris on an Attic plate, ca. 575-525 BC
Goddess of strife and discord
Symbol Golden Apple of Discord
Parents Nyx (alone), or Zeus and Hera
Siblings Ares, Hephaestus, Hebe or Thanatos, Hypnos, keres
Children Dysnomia
Roman equivalent Discordia
Greek deities
series
Primordial deities
Titans and Olympians
Aquatic deities
Chthonic deities
Other deities
Personified concepts
Eris (Ancient Greek: Ἔρις, "Strife") is the Greek goddess of strife and discord, her name being translated into Latin as Discordia. Her Greek opposite is Harmonia, whose Latin counterpart is Concordia. Homer equated her with the war-goddess Enyo, whose Roman counterpart is Bellona. The dwarf planet Eris is named after the goddess, as is the religion Discordianism.

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Eris (dwarf planet)

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Eris
Eris (centre) and Dysnomia (left of centre), taken by the Hubble Space Telescope
Eris (centre) and Dysnomia (left of centre).
Hubble Space Telescope
Discovery
Discovered by M. E. Brown,
C. A. Trujillo,
D. L. Rabinowitz[1]
Discovery date January 5, 2005[2][g]
Designations
MPC designation 136199 Eris
Pronunciation /ˈɪərɨs/, or /ˈɛrɨs/ as in Greek Έρις [a]
Named after Eris
Alternative names 2003 UB313[3]
Minor planet
category
dwarf planet,
TNO,
plutoid,
SDO,
and binary[4][5]
Adjective Eridian
Epoch March 6, 2006
(JD 2453800.5)[6]
Aphelion 97.56 AU
14.60×109 km
Perihelion 37.77 AU
5.65×109 km
Semi-major axis 67.67 AU
10.12×109 km
Eccentricity 0.441 77
Orbital period 203,600 days
557 years
Average orbital speed 3.436 km/s
Mean anomaly 197.634 27°
Inclination 44.187°
Longitude of ascending node 35.869 6°
Argument of perihelion 151.430 5°
Satellites Dysnomia
Physical characteristics
Mean radius 1163 ± 6 km[7][8]
Surface area 17,000,000 sq km (6,560,000 sq mi)
Mass (1.67 ± 0.02)×1022 kg[9]
0.0028 Earths
0.23 Moons
Mean density 2.52 ± 0.05 g/cm3[7][10]
Equatorial surface gravity 0.827 m/s2
Escape velocity 1.384 km/s
Sidereal rotation
period
25.9 ± 8 hr[3]
Albedo 0.96+0.09
−0.04
[7]
Surface temp.
   (approx)
min mean max
30 K 42.5 K 55 K
Spectral type B-V=0.78, V-R=0.45[11]
Apparent magnitude 18.7[12]
Absolute magnitude (H) −1.19 ± 0.3[3]
Angular diameter 40 milli-arcsec[13]
Eris, formal designation 136199 Eris, is the most massive known dwarf planet[i] in the Solar System and the ninth most massive body known to orbit the Sun directly. It is estimated to be 2326 (±12) km in diameter,[8] and 27% more massive than Pluto, or about 0.27% of the Earth's mass.[9][14]
Eris was discovered in January 2005 by a Palomar Observatory-based team led by Mike Brown, and its identity was verified later that year. It is a trans-Neptunian object (TNO) and a member of a high-eccentricity population known as the scattered disc. It has one known moon, Dysnomia. As of 2011, its distance from the Sun is 96.6 AU,[12] roughly three times that of Pluto. With the exception of some comets, Eris and Dysnomia are currently the most distant known natural objects in the Solar System.[2][h]
Because Eris appeared to be larger than Pluto, its discoverers[15] and NASA initially described it as the Solar System’s tenth planet. This, along with the prospect of other similarly sized objects being discovered in the future, motivated the International Astronomical Union (IAU) to define the term planet for the first time. Under the IAU definition approved on August 24, 2006, Eris is a "dwarf planet", along with objects such as Pluto, Ceres, Haumea and Makemake.[16]
In 2010, preliminary results from observations of a stellar occultation by Eris on November 6 suggested that its diameter may be only 2,326 km, which would make it essentially the same size as Pluto.[17] Given the error bars in the different size estimates, it is currently uncertain whether Eris or Pluto has the larger diameter.[18] Both Pluto and Eris are estimated to have solid-body diameters of about 2330 km.[18]

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