Last week a small asteroid became the closest natural celestial object to pass by the Earth. It posed no danger but it was close. It was found by astronomers at the Lowell Observatory in Arizona, which conducts a sky survey for so-called Near Earth Objects. The 4 - 8 metre rock passed just 88,000 kilometres from the Earth on 27 September. That is 0.23 of the distance from the Earth to the Moon. Designated 2003 SQ222 it was detected 11 hours after its closest approach. Observations made by professionals and amateurs have allowed its orbit to be determined. It circles the Sun every 1.85 years. Experts say the object is far too small to have posed a danger to Earth, although it would have been a spectacular fireball had it entered and partially fragmented in our atmosphere.

The previous record for closest approach of an asteroid was 108,000 km in 1994 by an object named 1994 XM1 that was about the same size as 2003 SQ222.

View: Full Article | Source: BBC News

I wonder how many near misses there are that astronomers don't manage to detect, or how close we have been in the past to having been hit by a much larger and potentially devastating asteroid that nobody knew about at the time.

That is an intresting thought Saruman. I bet there has been many a time. Makes you wonder doesn't it.

Small asteroids of the size quoted above will have been missed hundreds of times as they swept past the Earth. In fact, several have already been detected exploding in the upper atmosphere, and one (August 1972 above Montana) was actually filmed as it hit the atmosphere at such a shallow angle that it literally skipped back out into space !

Chris Low.