Monday, April 21, 2008

Could we be hit by an asteroid?

The chances of Earth being hit are greater than we thought

by Mark Henderson: Science Notebook

Nasa has been known to make schoolboy errors from time to time. In 1999, for instance, its Mars Climate Orbiter crashed because scientists forgot to convert between imperial and metric units. Last week a German schoolboy suggested it had goofed again. An asteroid called Apophis caused a brief stir in 2004 when calculations indicated it had a 3 per cent risk of a collision with Earth in 2029. It was accordingly named after the Egyptian god of destruction.
As usually happens, further observations revealed a false alarm. Apophis will miss us - only by a smidgen in astronomical terms, but by more than enough for life to go on. The chances of disaster are just one in 45,000.
According to Nico Marquardt, however, Nasa's sums are wrong. Apophis, the 13-year-old calculated, will fly close enough to strike a satellite, which could throw it into a more dangerous orbit.

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