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, provisionally known as 2005 YU55, is a potentially hazardous asteroid〔 360±40 meters in diameter, as measured after its Earth flyby.〔 Previously it was estimated at 310 meters〔(The Herschel Space Observatory catches a glimpse of the minor planet during its rendezvous with Earth (November 17, 2011) )〕 or about 400 m (1,300 feet) in diameter.〔〔 It was discovered on 28 December 2005 by Robert S. McMillan at Steward Observatory, Kitt Peak.〔 On 8 November 2011 it passed 0.85 lunar distances (324,900 kilometers; 201,900 miles)〔 from Earth. == 8 November 2011 flyby == In February 2010, was rated 1 on the Torino Scale for a potential pass near Earth on November 10, 2103,〔 that posed no unusual level of danger. On 19 April 2010, radar ranging by the Arecibo radio telescope reduced uncertainties about the orbit by 50%.〔 This improvement eliminated any possibility of an impact with Earth within the next 100 years.〔 It was removed from the Sentry Risk Table on 22 April 2010 and as such it now has a rating of 0 on the Torino Scale.〔 It is now known that on 10 November 2103 will be roughly 2 AU from Earth.〔 On 8 November 2011 at 23:28 UT the asteroid passed from Earth.〔 On 9 November 2011 at 07:13 UT the asteroid passed from the Moon.〔 During the close approach the asteroid reached about apparent magnitude 11,〔〔 and would have been visible to experienced observers using high-end binoculars with an objective lens of 80+ mm if it were not for bright moonlight preventing a true dark sky. Since the gibbous moon did interfere with the viewing,〔 observers trying to visually locate the asteroid required a telescope with an aperture of 6 inches (15 centimeters) or larger.〔〔 The next time a known asteroid this large will come this close to Earth will be in 2028〔 when passes from Earth.〔 According to Jay Melosh, if an asteroid the size of (~400 m across) were to hit land, it would create a crater across, deep and generate a seven-magnitude-equivalent-earthquake.〔 The chances of an actual collision with an asteroid like is about 1 percent in the next thousand years.〔 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「(308635) 2005 YU55」の詳細全文を読む スポンサード リンク
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