[Steve_Seattle]

500 meters across

If I'm not mistaken, an asteroid anywhere near that size would have a devastating impact, much larger than any atomic weapon and possibly enough to kill millions and disrupt the earth's atmosphere for months or even years.

[RobRoy]

>>500 meters across

If I'm not mistaken, an asteroid anywhere near that size would have a devastating impact, much larger than any atomic weapon and possibly enough to kill millions and disrupt the earth's atmosphere for months or even years.<<

And doesn't it bother you that we would have had only a couple of days notice? In all the movies we have MONTHS to get our affairs in order.

[cogitator]

If I'm not mistaken, an asteroid anywhere near that size would have a devastating impact, much larger than any atomic weapon and possibly enough to kill millions and disrupt the earth's atmosphere for months or even years.

Since 500m is about 1/4 mile for those who prefer the English units, you're right. That would be bad, but not necessarily catastrophic. Depends on where it hits: the ocean could probably accept that without major catastrophe. That's not to say we wouldn't notice.

The famous Barringer "Meteor Crater" in Arizona, which is about 1.6 km in diameter, was reportedly (on one Web site) formed by a meteor about 25m in diameter.

Found a reference that says the crater diameter is roughly 10x the impactor diameter. If the estimate about Barringer Crater is right, then the crater should be 250m in diameter -- and it's actually 1600m in diameter, which is a factor of 64. So let's use those as the lower and upper bounds.

For a 500m impactor, the lower bound for the crater diameter is: 5000m (5km, 3miles).

The upper bound for the diameter is 32 km, 19.2 miles. I'm sure there's a scaling factor, but I would think it's reasonable to say that a 500m-diameter object would make a crater several miles in diameter. That's gotta hurt a bit.