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| discovery = yes | discovered = 1 October 2010 | discoverer = WISE spacecraft | discovery_ref = 〔 | discovery_site = LEO, polar orbit | background = #FFFFC0 | name = | mp_category = Earth trojan Aten (2014)〔 Apollo (2013)〔(WayBack Machine 2013 Epoch@MPC )〕 | orbit_ref = 〔 | epoch = 9 December 2014 (JD 2457000.5) | uncertainty = 0 | observation_arc = 2.10 yr | semimajor = 0.99987 AU | perihelion = 0.80923 AU | aphelion = 1.1905 AU | eccentricity = 0.19066 | period = 1.00 yr (365.18 d) | inclination = 20.888° | asc_node = 96.506° | arg_peri = 45.902° | mean_anomaly = 319.80° | avg_speed = 9.1 m/s〔 | physical_characteristics = yes | dimensions = ~ 300 m〔 | density = | surface_grav = | magnitude = 20.8 (when near Earth) to 23.6 | abs_magnitude = 20.8〔 }} is a near-Earth asteroid and the first Earth trojan ever discovered; it precedes Earth in its orbit around the Sun.〔〔 Trojan objects are most easily conceived as orbiting at a Lagrangian point, a dynamically stable location (where gravitational and centrifugal forces balance) 60 degrees ahead of or behind a massive orbiting body, in a type of 1:1 orbital resonance. In reality, they oscillate (librate) around such a point. Such objects had previously been observed in the orbits of Mars, Jupiter, Neptune, and the Saturnian moons Tethys and Dione. has a diameter of about .〔 Its path oscillates about the Sun–Earth Lagrangian point (60 degrees ahead of Earth), shuttling between its closest approach to Earth and its closest approach to the point (180 degrees from Earth) about every 400 years. The asteroid was discovered in October 2010 by the NEOWISE team of astronomers using NASA's Wide-field Infrared Survey Explorer (WISE).〔 == Discovery == WISE, a space telescope launched into Earth orbit in December 2009, imaged in October 2010 while carrying out a program to scan the entire sky from January 2010 to February 2011. Spotting an asteroid sharing Earth's orbit is normally difficult from the ground, because their potential locations are generally in the daytime sky.〔 After follow-up work at the University of Hawaii and the Canada–France–Hawaii Telescope, its orbit was evaluated on 21 May 2011 and the trojan character of its motion was published in July 2011. The orbital information was published in the journal ''Nature'' by Paul Wiegert of the University of Western Ontario, Martin Connors of Athabasca University and Christian Veillet, the executive director of the Canada–France–Hawaii Telescope.〔〔 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「2010 TK7」の詳細全文を読む スポンサード リンク
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