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View Full Version : Discussion: Fewer Asteroids Threaten the Earth



Fraser
2003-Jul-21, 05:39 PM
SUMMARY: Researchers have built a computer simulation that better predicts how large asteroids will interact with the Earth's atmosphere. They found that more asteroids blow up in the atmosphere than previously thought, reducing the risk of they hitting populated areas or causing tidal waves. Their model says that an asteroid has to be 200 metres in diameter or above before it can get through the atmosphere, and these only hit the Earth once every 170,000 years.


Comments or questions about this story? Feel free to share your thoughts.

knealy
2003-Jul-21, 06:57 PM
Perhaps I'm not clear on this story. Clearly meteors of much smaller size than 200 meters have made it to ground. I witnessed one. Are asteroids fundamentally different from meteors?

What practical difference does it make if a large meteor could still impact but not an asteroid? Do I care which one hits me?

Finally, if the asteroid blows up rather than hits, couldn't it actually cause even more damage than if it hit. After all nuclear bombs are designed to blow up before hitting in order to maximize the damage.

:blink:

Al Globus
2003-Jul-21, 07:05 PM
Unfortunately, asteroids that air-burst rather than hit the ground can be exremely deadly. It's a little like an enormous nuclear bomb going off a few miles up with no radiation, only blast. The asteroid that hit Russia near the early part of this century was an air-burst. There was no crater, but trees were flattened for 10s of miles in every direction. If had hit a city, that city would have been demolished and everyone killed. The best estimate of asteroid size is around 60-70 meters diameter (according to memory).

Fraser
2003-Jul-21, 07:08 PM
Oh, air bursts can be tremendously destructive. They just won't cause tsunamis. So, count your blessings.

cyberbum
2003-Jul-21, 07:42 PM
Would it be as destructive if it was to burst where most meteorites burn up, in the upper parts of the atmosphere? Also, the space shuttle has to come in at a very critical angle, or it will skip off the atmosphere, would this not also aid in the shielding of the effects of the burst?