Near Misses and You

The Earth’s orbit intersects with the orbits of many asteroids. NASA estimates “many” to be about 1000 to 4000, that are bigger than half-mile across, which is when an asteroid begins to pose a threat to human civilization (as you may have learned from Armageddon).

Toutatis, an asteroid 2 miles in diameter, passed by Earth January 3, 1993 at approx 2 million miles away. Before Toutais, on March 23, 1989 an asteroid about half a mile across sauntered by at 0.7 million miles (Oh, and 'Guitar Hero' has sparked an 80's comeback).

Now, nearly everyone will agree that an asteroid (or comet) ended the Cretaceous period 65 million years ago with the mass extinction of the dinosaurs, while some will insist that there was no such period and the Earth was created 5000 years ago (or something equally silly).

250 million years ago Trilobites ruled the Earth, until a mass extinction wiped them all out, ending the Permian period.
Is that too far back to concern ourselves with?
How about the Eocene period at 35 million years ago, which ended with the mass extinction of many land mammals? (This just in, Court overturns fine on Jackson's 'wardrobe malfunction')

Whenever I bring up these topics and ruin perfectly good dinner parties I’m always met with an obtuse skepticism, “Well, don’t you think the Universe has tired of these mass extinction antics by now?” or “Certainly humanity has reached a measure of intelligence where we can dispatch any cosmical threat” or there’s those responses I get back from the “5000 years ago” crowd.

I suppose those people are the worst of the bunch, since they have already reached the conclusion that everything is and will always be fine and dandy, that it’s all part of the plan, and communication comes to an abrupt stop (Kim Kardashian has been tapped as the latest celebrity to join the cast of Dancing With The Stars).