(143649) 2003 QQ47
(143649) 2003 QQ47, provisionally designated: 2003 QQ47, is a kilometer-sized asteroid and synchronous binary system, classified as near-Earth object and potentially hazardous asteroid of the Apollo group. It became briefly notable upon its discovery in late August 2003, when media outlets played up a very preliminary report that it had a 1 in 250,000 chance of impacting into Earth on 21 March 2014.[4] The discovery of a companion, approximately 310 meters (1,000 ft) in diameter, was announced in September 2021. Description2003 QQ47 was discovered on 24 August 2003.[1] It was added to the Sentry Risk Table on 30 August 2003.[4] By 31 August 2003 (with an observation arc of 7 days) the odds of an impact on 21 March 2014 were already reduced to 1 in 1.7 million.[5] The asteroid was removed from the Sentry Risk Table on 14 September 2003, indicating there is no risk of an impact by it in the next 100 years.[6] 2003 QQ47 safely passed within 0.1283 AU (19,190,000 km; 11,930,000 mi) of Earth on 26 March 2014.[2][7] With an observation arc of 10 years and an orbital uncertainty of 0, its orbit and future close approaches are well-determined.[2] Preliminary reportsOn 3 September 2003 a NASA press release wrote,
2003 QQ47 has a diameter of approximately 1.24 km, and a mass of approximately 2.0×1012 kg[citation needed]. If it were to hit the Earth, it would be a major event, with an energy of approximately 350,000 megatons of TNT (1.5 ZJ), enough to cause global damage. Sara Russell, a meteorite researcher at London's Natural History Museum, told the BBC on 2 September 2003 that she was not worried that 2003 QQ47 would be a danger; "The odds are very, very low ... We have to keep some kind of perspective", she said.[8] As a result of the press coverage of asteroids such as 2003 QQ47, astronomers are now planning to re-word the Torino scale, or to phase it out completely in favour of a scale that is less likely to generate false alarms that may reduce public confidence in genuine alerts. Binary systemA minor-planet moon, provisionally designated S/2021 (143649) 1, was first detected on 29 August 2021, by Petr Pravec, Peter Kušnirák, Kamil Hornoch, and others using photometric data from ESO's La Silla Observatory in Chile.[3] The discovery was announced on 17 September 2021. The secondary measures a third the size of its primary (Ds/Dp-ratio of 0.33), resulting in a mean-diameter of approximately 310 meters. It is estimated to be tidally locked, orbiting 1.4 kilometers (4,600 ft) from the primary every 13.065 hours. The primary has a rotation period of 2.6446±0.0007 hours and a derived diameter of 0.94±0.40 kilometers, for a resulting effective diameter (system) of 0.995±0.42 kilometers.[3] In fiction
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