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| discovery_ref = 〔 | discoverer = Spacewatch (291) | discovered = 30 October 2002 | discovery_site = Kitt Peak National Obs. | mp_name = | alt_names = | mp_category = Cubewano (MPC)〔 Extended (DES)〔 | orbit_ref = 〔 | epoch = 27 June 2015 (JD 2457200.5) | uncertainty = 3 | observation_arc = | aphelion = 48.803 AU | perihelion = 36.509 AU | semimajor = 42.656 AU | eccentricity = 0.1441 | period = 278.60 yr (101,758 days) | mean_anomaly = 294.21° | inclination = 19.463° | asc_node = 204.65° | arg_peri = 277.89° | avg_speed = 4.54 km/s | satellites = 1 (ø: ~ 190–260 km)〔〔 | dimensions = 〔 | mass = 〔 | density = 〔 | surface_grav = 0.075 m/s2 | escape_velocity = 0.227 km/s | sidereal_day = 〔 | rot_velocity = | spectral_type = (pushing red) B−V=1.12 V−R=0.61〔 B−V=0.95 V−R=0.56〔〔 U−B=0.26 B−V=0.98 V−R= B−R=1.52 V−I= R−J=1.28 V−J= J−H= V−H=2.22 〔 | magnitude = 19.8 〔 | abs_magnitude = 〔 3.9 〔 | albedo = 〔 〔 | single_temperature = ≈ 43 K }} is a possible dwarf planet that orbits the Sun in the Kuiper belt beyond Neptune. Its orbit takes roughly 280 years, and it has one known moon. This moon makes it much easier to calculate mass, and when the size is known, also a density. The low density of about 0.82 g/cm3 has been a surprise to astronomers.〔(Ron Cowen - Nature - Astronomers surprised by large space rock less dense than water Kuiper belt object challenges planet-formation theories. (13 November 2013) )〕 It is a trans-Neptunian object with an absolute magnitude of 3.9,〔 making it highly likely to be a dwarf planet. The Spitzer Space Telescope results estimate it to be about 681 km in diameter.〔 It was discovered on 30 October 2002, by the Spacewatch program.〔 It is a mid-sized cubewano similar in size to 20000 Varuna. == Classification == has a perihelion (closest approach to the Sun) of 36.7 AU,〔 which it will next reach in 2065.〔 As of 2010, is 41 AU from the Sun.〔 The Minor Planet Center (MPC) classifies as a cubewano〔 while the Deep Ecliptic Survey (DES) classifies it as scattered-extended.〔 The DES using a 10 My integration (last observation: 2009-10-22) shows it with a minimum perihelion (qmin) distance of 36.3 AU.〔 has been observed 60 times with precovery images back to 1991.〔 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「(55637) 2002 UX25」の詳細全文を読む スポンサード リンク
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