jeudi 13 octobre 2016

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Earth-grazing meteoroid of 13 October 1990

The Earth-grazing meteoroid of 13 October 1990 entered the atmosphere above Czechoslovakia and Poland and, after 9.8 seconds, returned to space. Named EN131090, the 44-kilogram (97 lb) meteoroid was observed travelling 409 kilometres (254 mi) at a speed of 42 km/s (26 mi/s) by cameras of the European Fireball Network. Its apparent magnitude peaked at −6.3, several times brighter than Venus's peak magnitude. Observations of such events are quite rare; this was the second recorded by scientific astronomical instruments (after the 1972 Great Daylight Fireball) and the first recorded from two distant positions, which enabled the calculation of several of its orbital characteristics. The encounter with Earth significantly changed its orbit and, to a smaller extent, some of its physical properties, including its mass and the structure of its upper layer. If the meteoroid had reached the lower atmosphere, it would have overheated and exploded high above the ground, leaving at most a few small meteorites that posed no danger to the Earth's surface. (Full article...)



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