Near Miss

Earth-grazing meteoroid of 13 October 1990The Earth-grazing meteoroid of 13 October 1990 entered the atmosphere aboveCzechoslovakia 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 …. 93,600 miles per hour) by cameras of the European Fireball Network.

(On the surface of the Earth, the escape velocity is about 11.2 km/s, which is approximately 33 times the speed of sound (Mach 33) and several times the muzzle velocity of a rifle bullet (up to 1.7 km/s). However, at 9,000 km altitude in “space”, it is slightly less than 7.1 km/s.)

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.

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