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| adjectives = Haumean | note = yes | alt_names = 2003 EL61 | named_after = Haumea | mp_category = Dwarf planet, plutoid, TNO,〔〔 7:12 resonance, (delisted cubewano) Haumea family, and trinary〔 | orbit_ref = 〔 | epoch = 2014-12-09 (JD ) | aphelion = (7.702 Tm) | perihelion = (5.229 Tm) | semimajor = (6.465 Tm) | eccentricity = | period = 284.12 yr () | inclination = 28.19° | asc_node = 121.79° | arg_peri = 240.20° | mean_anomaly = 209.07° | avg_speed = | satellites = 2 | physical_characteristics = yes | dimensions = 1,920 × 1,540 × 990 km〔 ≈ 1,960 × 1,518 × 996 km (Keck)〔 | mean_radius = 〔 (Herschel)〔〔 690 km〔 (Spitzer)〔 ≈ 718 km (Keck) | surface_area = ≈ | volume = | mass = 〔 | density = 2.6 g/cm3〔〔 2.6–3.3 g/cm3〔 | surface_grav = 0.63 m/s2 | escape_velocity = 0.91 km/s | sidereal_day = ()〔 | spectral_type = (Neutral) B−V = 0.64, V−R = 0.33 〔 B0−V0 = 0.646 〔 | magnitude = 17.3 (opposition)〔〔 | abs_magnitude = 〔 | albedo = 〔 〔 〔 0.70–0.75 〔 | single_temperature = < 50 K〔 }} 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 suggest it is an ellipsoid, with its major axis twice as long as its minor. Nonetheless, its gravity is believed sufficient for it to have relaxed into hydrostatic equilibrium, making it a dwarf planet. This elongation, along with its unusually rapid rotation, high density, and high albedo (from a surface of crystalline water ice), are thought to be the results of a giant collision, which left Haumea the largest member of a collisional family that includes several large trans-Neptunian objects (TNOs) and its two known moons, Hiʻiaka and Namaka. Its extreme elongation makes it unique among known dwarf planets. == Classification == Haumea is a plutoid, a dwarf planet residing beyond Neptune's orbit.〔 Its classification as a dwarf planet means it is presumed to be massive enough to have been rounded by its own gravity but not to have cleared its neighbourhood of similar objects. Although Haumea appears to be far from spherical, its ellipsoidal shape is thought to result from its rapid rotation, in much the same way that a water balloon stretches out when tossed with a spin, and not from a lack of sufficient gravity to overcome the compressive strength of its material.〔 Haumea was initially listed as a classical Kuiper belt object (classical KBO) in 2006 by the Minor Planet Center, but no longer.〔 The nominal trajectory suggests that it is in the weak 7:12 resonance with Neptune (orbiting the Sun 7 times for every 12 orbits of Neptune), because its perihelion distance of 35 AU is near the limit of stability with Neptune.〔 There are precovery images of Haumea dating back to March 22, 1955 from the Palomar Mountain Digitized Sky Survey.〔 Further observations of the orbit will be required to verify its dynamic status. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Haumea」の詳細全文を読む スポンサード リンク
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