Asteroid To Pass Close By

[wollery]

Curt, I admit that on final approach an asteroid/meteor would not appear to move much wrt the background, but I don't think we're talking more than a few hours. You have to remember that in a plane there's very little background to campare against, but when we look at astronomical objects even the slightest angular change is easily measurable against the background of stars and galaxies.

Joshua, not only are we constantly changing direction, the asteroid is as well. We're on an almost circular orbit, the asteroid will be on a fairly eccentric elliptical orbit, which will be perturbed by the Earth, the Moon and any other large mass it gets anywhere near!

 

[Abdul Alhazred]

Actually, the chance of a major asteroid striking the Earth within any given lifetime is about 1 in 200.

Let's examine this claim. Take a "lifetime" as a generous 100 years. 200 * 100 = 20,000.

I'm defining a "major" asteroid strike as one that leaves a visible mark on the geography for millenia, not just a meteorite that punches a hole in the roof.

I don't know how to calculate the probability, but I have a strong impression that your estimate is way too high.

 

[Wrath of the Swarm]

http://www.urbanlegends.com/death/dying_from_asteroid_strike.html

Note, please, that those odds are for a truly huge strike. A merely large one is much more common.

Probably the most recent event that would qualify is Tunguska. Before that, there was a massive strike in Nebraska that was probably witnessed by the aboriginal natives, and that's about 20,000 years ago...

 

[CurtC]

Wrath, wouldn't there likely be some between the Nebraska event and Tunguska? I mean, we know about Tunguska only because there were enough literate people in the area to record it. I'm not aware that it left any permanent scars, so if this had happened 200 years earlier, we likely wouldn't have known, unless it hit in Europe or the Middle East.

 

[Wrath of the Swarm]

Correct. The bigger the event was, the better a record (natural or otherwise) we'll be likely to have for it.

We can only really guess at how often smaller objects hit the Earth, as we've only had the capacity to notice them for a few decades.

 

[Drooper]

Does anybody else remember a more naive, innocent time, when all we had to worry about was preemptive nuclear strike?