[astroCS] Closest asteroid yet flies past Earth

Marek Husarik mhusarik at ta3.sk
Sat Oct 4 06:35:38 UTC 2003

Za predosly prispevok hovori aj nasledujuci clanok z New Scientist 

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18:17 02 October 03 
NewScientist.com news service 
An asteroid about the size of a small house passed just 88,000 kilometres
from the Earth by on Saturday 27 September - the closest approach of a
natural object ever recorded. Geostationary communication satellites circle
the Earth 42,000km from the planet's centre.

The asteroid, designated 2003 SQ222, came from inside the Earth's orbit and
so was only spotted after it had whizzed by. The first sighting was on
Sunday 28 by the Lowell Observatory Near-Earth Object Search program in
Arizona, US. 

Amateur astronomer Peter Birtwhistle of Great Shefford, Berkshire, UK, then
photographed it on Monday 29. This provided data that helped Brian Marsden,
of the Harvard-Smithsonian Center for Astrophysics, to calculate its orbit. 

The asteroid's 1.85-year orbit is quite eccentric, indicating it cannot be a
man-made object, Marsden says. He estimates the asteroid measured less than
10 metres. This is too small to have posed a danger to Earth, although it
would have made a spectacular fireball had it entered the atmosphere.

The passage came at about 2300 GMT, only 10 hours after a bright fireball
streaked over the Orissa region of India. Indian villagers have found pieces
of the meteorite, which reportedly cause two house fires. However, this
event was not connected to the fly past of 2003 SQ222, says Marsden.

The previous record for closest approach of an asteroid - 108,000km measured
from the centre of the Earth - was set in 1994 by another 10m object named
1994 XM1. 

But the third-closest approach - at 120,000km - was object 2002 MN, which
was about 80m in diameter. If on target, that could have exploded in the
Earth's lower atmosphere and devastated a couple of thousand square
kilometres on the ground.

Another small asteroid, 2003 SW130, missed the Earth by 160,000km on 19
September, making it a busy month for asteroid watchers.
Jeff Hecht


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