How BIG must a ASTEROID be to DESTROY MANKIND?

Question

How BIG?

What SPEED must it come in to destroy mankind..possibly the planet..

Answer 1

Half the size of Texas.

Answer 2

It depends on two factors-- SPEED and MASS.

To completely destroy and pulverize the Earth would take Something about the size of Mars for instance.

Read #3 on this list--

http://www.livescience.com/technology/de...

Answer 3

More than 10 miles in diameter. Maybe more than 20. We actually don't know for sure. There are asteroids much bigger than that, but they are all safely in stable orbits between Mars and Jupiter. A few asteroids are in Earth crossing orbits, But almost all of those is smaller than 10 miles in diameter. A 1 mile asteroid could cause a lot of damage, like take out a big area, but not cause an extinction event. We are pretty sure we have discovered all the asteroids big enough to cause extinction. The search goes on for the smaller ones. All the big ones seem it be safely missing us and knowing when and where a smaller one would hit could save millions of lives by evaculating the area. But evacuating all of, say Europe, would be WAY more expensive than mounting a massive, emergency, cost is no object, bigger than the Apollo program effort to deflect it.  

Answer 4

To wipe out man kind it at least has to be the size of Texas and its gotta be coming in at about 300 Miles Per Hour  

Answer 5

Something as small as about 3 miles in diameter would create an ecological catastrophe severe enough to possibly exterminate humans.  The planet would survive, though.

Answer 6

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Answer 7

It's not how big, it's how much energy it carries.  This is a function of both mass and velocity.  I think you could wipe out New York by dropping a hammer on it, provided you can find a way of having the hammer arrive at half the speed of light.

  

Answer 8

45.