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39382 Opportunity, also designated 2696 P-L, is a Hilidan asteroid from the outermost region of the asteroid belt, roughly 5 kilometers in diameter. It was discovered by Dutch astronomer couple Cornelis and Ingrid van Houten-Groeneveld and Dutch–American astronomer Tom Gehrels, on 24 September 1960. The asteroid was spotted by examining photographic plates taken at the U.S. Palomar Observatory, California.〔 ''Opportunity'' orbits the Sun at a distance of 3.2–4.8 AU once every 7 years and 11 months (2,883 days). Its orbit shows a notable eccentricity of 0.20 and is tilted by 3 degrees to the plane of the ecliptic. Located in the outermost part of the main-belt, the asteroid is a member of the Hilda family, a large group of asteroids that are thought to have originated from the Kuiper belt. They orbit in a 3:2 orbital resonance with the gas giant Jupiter, meaning that for every 2 orbits Jupiter completes around the Sun, a Hildian asteroid will complete 3 orbits.〔 The asteroid's orbit does not cross the path of any of the planets and therefore it will not be pulled out of orbit by Jupiter's gravitational field. As a result of this, it is likely that the asteroid will remain in a stable orbit for thousands of years. The designation ''P–L'' stands for ''Palomar–Leiden'', named after Palomar Observatory and Leiden Observatory, which collaborated on the fruitful Palomar–Leiden survey in the 1960s. Gehrels used Palomar's Samuel Oschin telescope (also known as the 48-inch Schmidt Telescope), and shipped the photographic plates to Ingrid and Cornelis van Houten at Leiden Observatory. The trio are credited with several thousand asteroid discoveries. Little is known about the asteroids size, composition, albedo and rotation, despite having a well-observed orbit with the lowest possible uncertainty – a condition code of 0 – and an observation arc that spans over a period of more than half a century.〔 Based on its absolute magnitude of 14.4, its diameter could be anywhere between 3 and 7 kilometers, assuming an albedo in the range of 0.05 to 0.25.〔 Since outer main-belt asteroids typically have a spectral type of a darker carbonaceous, rather than a brighter rocky body, its true diameter may be at the upper end of NASA's generic conversion table, as, for a given absolute magnitude, an object's diameter increases, when its albedo decreases.〔 On October 11, 2004, following a proposal by van Houten-Groeneveld in 2002, the minor planet was named ''Opportunity'', after the Mars Exploration Rover.〔 == See also == * 37452 Spirit 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「39382 Opportunity」の詳細全文を読む スポンサード リンク
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