NASA/ESA/CSA JWST NIRCam; Ana Carolina de Souza Feliciano et al. & Melina Thévenot, CC BY-SA 4.0Eris
The distant world whose discovery got Pluto demoted
Overview
Eris 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. 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.
Source: Wikipedia
Why it matters
- Discovered in 2005; slightly smaller than Pluto in diameter but about 27% more massive.
- Its 558-year orbit carries it out to about 98 AU, nearly three times Pluto's average distance.
- A highly reflective surface of frozen methane and nitrogen; it has one known moon, Dysnomia.
System
- Discovered
- 2003 · direct observation
- Discoverers
- Brown, M. E., Trujillo, C. A., Rabinowitz, D.
- Star
- Sun · G2 V · 5,772 K · 1 M☉
- System
- 8 known planets
Orbit in the Solar System
| World | Period | Distance | Radius | Mass | Temp. |
|---|---|---|---|---|---|
| Mercury | 88 d | 0.387 AU | 0.38 R⊕ | 0.055 M⊕ | 440 K |
| Venus | 224.7 d | 0.723 AU | 0.95 R⊕ | 0.82 M⊕ | 737 K |
| Earth | 365.2 d | 1 AU | 1 R⊕ | 1 M⊕ | 288 K |
| Mars | 687 d | 1.52 AU | 0.53 R⊕ | 0.11 M⊕ | 208 K |
| Ceres | 4.6 yr | 2.77 AU | 0.07 R⊕ | 0.94 ×10²¹ kg | — |
| Jupiter | 11.9 yr | 5.2 AU | 1 R♃ | 1 M♃ | 163 K |
| Saturn | 29.4 yr | 9.57 AU | 0.84 R♃ | 95.11 M⊕ | 133 K |
| Uranus | 83.7 yr | 19.16 AU | 0.36 R♃ | 14.53 M⊕ | 78 K |
| Neptune | 163.7 yr | 30.18 AU | 3.88 R⊕ | 17.08 M⊕ | 73 K |
| Pluto | 247.9 yr | 39.48 AU | 0.19 R⊕ | 13 ×10²¹ kg | 48 K |
| Haumea | 282 yr | 43.1 AU | 0.12 R⊕ | — | 50 K |
| Makemake | 306.6 yr | 45.6 AU | 0.11 R⊕ | 3.1 ×10²¹ kg | — |
| Eris | 561.3 yr | 67.9 AU | 0.18 R⊕ | 17 ×10²¹ kg | 43 K |
| Sedna | 12,676.2 yr | 544 AU | 0.08 R⊕ | — | 12 K |
By the numbers
- Radius
- 0.18 R⊕1,163 km
- Mass
- 17 ×10²¹ kg0.02 ×10²⁴ kg
- Orbital period
- 561.3 yr
- Distance from Sun
- 67.9 AU10,158 million km
- Eccentricity
- 0.438elliptical
- Mean temperature
- 43 K
Sources
Image: NASA/ESA/CSA JWST NIRCam; Ana Carolina de Souza Feliciano et al. & Melina Thévenot, CC BY-SA 4.0 · CC BY-SA 4.0 · image page
Text: Wikipedia (CC BY-SA 4.0). Taglines and highlights are editorial.