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Haumea (dwarf planet)

Haumea
2003 EL61 Haumea, with moons.jpg
Keck image of Haumea and its two moons. Hiʻiaka is above Haumea (center), and Namaka is directly below.
Discovery
Discovered by Brown et al.; Ortiz et al. (neither official)
Discovery date 2004 December 28 (Brown et al.); 2005 July (Ortiz et al.)
Designations
MPC designation (136108) Haumea
Pronunciation /hˈm.ə/ or /ˌhɑːˈm.ə/
Named after
Haumea
2003 EL61
Dwarf planet, plutoid, TNO,
7:12 resonance, (delisted cubewano)
Haumea family,
and trinary
Adjectives Haumean
Orbital characteristics
Epoch 2014-12-09 (JD 2457000.5)
Aphelion 51.483 AU
(7.702 Tm)
Perihelion 34.952 AU
(5.229 Tm)
43.218 AU
(6.465 Tm)
Eccentricity 0.19126
284.12 yr (103774 d)
Average orbital speed
4.531 km/s
209.07°
Inclination 28.19°
121.79°
240.20°
Known satellites 2
Physical characteristics
Dimensions

1,920 × 1,540 × 990 km

≈ 1,960 × 1,518 × 996 km (Keck)
Mean radius
620+34
−29
 km

≈ 650 km (Herschel)
690 km
575+125
−50
 km
(Spitzer)
≈ 718 km (Keck)
≈ 6.8×106 km2
Volume 1.5×109 km3
Mass (4.006±0.040)×1021 kg
0.00066 Earths
Mean density

2.6 g/cm3

2.6–3.3 g/cm3
0.63 m/s2
0.91 km/s
Sidereal rotation period
0.163146±0.000004 d
(3.9155±0.0001 h)
Albedo 0.804+0.062
−0.095

0.7±0.1
0.84+0.1
−0.2

0.70–0.75 
Temperature < 50 K
Spectral type
(Neutral)
B−V = 0.64, V−R = 0.33 
B0−V0 = 0.646 
17.3 (opposition)
0.03±0.43

1,920 × 1,540 × 990 km

2.6 g/cm3

Haumea, minor-planet designation 136108 Haumea, is a dwarf planet located beyond Neptune's orbit. It was discovered in 2004 by a team headed by Mike Brown of Caltech at the Palomar Observatory in the United States and independently in 2005, by a team headed by José Luis Ortiz Moreno at the Sierra Nevada Observatory in Spain, though the latter claim has been contested. On September 17, 2008, it was recognized as a dwarf planet by the International Astronomical Union (IAU) and named after Haumea, the Hawaiian goddess of childbirth.

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 indicate that it is a triaxial ellipsoid, with its major axis twice as long as its minor. Its gravity is thought to be sufficient for it to have relaxed into hydrostatic equilibrium, making it a dwarf planet. Haumea's elongated shape together with its rapid rotation, high density, 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 (TNOs) and Haumea's two known moons, Hiʻiaka and Namaka.


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