Global InformationHaumea information
 Low-resolution Hubble Space Telescope image of Haumea and its two moons, Hi'iaka (top) and Namaka (bottom), June 2015 | |
| Discovery | |
|---|---|
| Discovered by |
|
| Discovery date |
|
| Designations | |
MPC designation | (136108) Haumea |
| Pronunciation | /haʊˈmeɪ.ə, ˌhɑːuː-/[nb 1] |
Named after | Haumea |
Alternative designations | 2003 EL61 |
Minor planet category |
|
| Adjectives | Haumean[7] |
| Symbol |  (mostly astrological) |
| Orbital characteristics[8] | |
| Epoch December 17, 2020 (JD 2459200.5) | |
| Uncertainty parameter 2 | |
| Observation arc | 65 years and 291 days (24033 days) |
| Earliest precovery date | March 22, 1955 |
| Aphelion | 51.585 AU (7.7170 Tm) |
| Perihelion | 34.647 AU (5.1831 Tm) |
Semi-major axis | 43.116 AU (6.4501 Tm) |
| Eccentricity | 0.19642 |
Orbital period (sidereal) | 283.12 yr (103,410 days)[9] |
Average orbital speed | 4.53 km/s[nb 2] |
Mean anomaly | 218.205° |
Mean motion | 0° 0m 12.533s / day |
| Inclination | 28.2137° |
Longitude of ascending node | 122.167° |
Time of perihelion | ≈ June 1, 2133[10] ±2 days |
Argument of perihelion | 239.041° |
| Known satellites | 2 (Hiʻiaka and Namaka) |
| Physical characteristics | |
| Dimensions |
|
Mean radius |
|
Surface area | ≈ 8.14×106 km2[nb 3][13] |
| Volume | ≈ 1.98×109 km3[nb 3][14] 0.0018 Earths |
| Mass | (4.006±0.040)×1021 kg[15] 0.00066 Earths |
Mean density |
|
Equatorial surface gravity | 0.93 m/s2 at poles to 0.24 m/s2 at longest axis |
Equatorial escape velocity | 1 km/s at poles to 0.71 km/s at longest axis |
Sidereal rotation period | 3.915341±0.000005 h[16] (0.163139208 d) |
Axial tilt | ≈ 126° (to orbit; assumed) 81.2° or 78.9° (to ecliptic)[nb 6] |
North pole right ascension | 282.6°±1.2°[17]: 3174 |
North pole declination | −13.0°±1.3° or −11.8°±1.2°[17]: 3174 |
Geometric albedo |
|
| Temperature | < 50 K[20] |
Spectral type |
|
Apparent magnitude | 17.3 (opposition)[23][24] |
Absolute magnitude (H) | 0.428±0.011 (V-band) [16] · 0.2 [9] |
Haumea (minor-planet designation: 136108 Haumea) is a dwarf planet located beyond Neptune's orbit.[25] It was discovered in 2004 by a team headed by Mike Brown of Caltech at the Palomar Observatory, and formally announced in 2005 by a team headed by José Luis Ortiz Moreno at the Sierra Nevada Observatory in Spain, who had discovered it that year in precovery images taken by the team in 2003. From that announcement, it received the provisional designation 2003 EL61. On September 17, 2008, it was named after Haumea, the Hawaiian goddess of childbirth, under the expectation by the International Astronomical Union (IAU) that it would prove to be a dwarf planet. Nominal estimates make it the third-largest known trans-Neptunian object, after Eris and Pluto, and approximately the size of Uranus's moon Titania. Precovery images of Haumea have been identified back to March 22, 1955.[9]
Haumea's mass is about one-third that of Pluto, and 1/1400 that of Earth. Although its shape has not been directly observed, calculations from its light curve are consistent with it being a Jacobi ellipsoid (the shape it would be if it were a dwarf planet), with its major axis twice as long as its minor. In October 2017, astronomers announced the discovery of a ring system around Haumea, representing the first ring system discovered for a trans-Neptunian object and a dwarf planet. Haumea's gravity was until recently thought to be sufficient for it to have relaxed into hydrostatic equilibrium, though that is now unclear. Haumea's elongated shape together with its rapid rotation, rings, and high albedo (from a surface of crystalline water ice), are thought to be the consequences of a giant collision, which left Haumea the largest member of a collisional family that includes several large trans-Neptunian objects and Haumea's two known moons, Hiʻiaka and Namaka.
- ^ New dwarf planet named for Hawaiian goddess Archived 2015-12-08 at the Wayback Machine (HeraldNet, September 19, 2008)
- ^ "DPS08 Webstreaming". Archived from the original on 2009-01-06. Retrieved 2009-02-14.
- ^ "365 Days of Astronomy". Archived from the original on 2012-02-20. Retrieved 2009-04-11.
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- ^ "Ellipsoid volume: 1.98395×10^9 km3". wolframalpha.com. 20 December 2019. Archived from the original on 25 July 2020. Retrieved 20 December 2019.
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