'Lost' asteroid could hit Earth

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'Lost' asteroid could hit Earth

by Geraint Smith, Science Correspondent At least one potentially dangerous asteroid is being discovered every night and the rate is increasing rapidly.

More than 300 asteroids with orbits that cross Earth's were found last year, and this year the discoveries are coming faster, Dr Duncan Steel of the University of Salford will tell the National Astronomy Meeting in Cambridge later this week.

However, even more worrying may be one that has gone missing.

"One, in particular, we need to find. It was seen for only 10 days in 1998, and it looked as though it might be on a potential collision course within the next 30 years.

"However, it was not seen for long enough to calculate the orbit to know for certain."

The object, known as 1998 OX 4, is about half a mile across, he said. "If it hit San Francisco, California would cease to exist. If it hit London, much of England would cease to exist."

The object that killed the dinosaurs was between five and 10 miles in size, but just 93 years ago an asteroid only 60 or 70 yards across blew up in the atmosphere above Siberia, producing a blast which, had it had Marble Arch as its centre, would have flattened all of London out to the M25.

"The chance of that occurring is small, but the consequences are so phenomenal that it is a hazard we must take seriously," Dr Steel said.

Dr Steel is one of six foreign scientists on Nasa's Spaceguard Committee, which made recommendations to the US Congress on how to deal with "Near Earth Objects".

The building blocks of life on Earth probably arrived as small fragments of comet that looked remarkably like the surface of the M1.

Dr Steel will today tell the National Astronomy Meeting it is likely they came in the shape of tiny meteoroids made of a tarry substance called keragin, billions of which still bombard the Earth. Although these vaporise high in the atmosphere, the chemicals of which they are made then float gently to Earth, largely intact.


-- Martin Thompson (mthom1927@aol.com), April 05, 2001

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