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ScottyMcGeester's avatar

Can someone explain to me the science behind an asteroid collision?

Asked by ScottyMcGeester (927 points ) March 25th, 2014

I’m fascinated with the destructive power asteroids/comets can have, and doomsday scenarios and all that.

I don’t understand exactly how they destroy things though.

I got confused when that asteroid hit Russia a couple or so years ago. Remember that? I remember asking someone what the asteroid looked like, but they said the asteroid disintegrated before it hit the ground.

Then how come in the videos it sounds like it landed and it was able to cause damage?

Is the damage created through soundwaves then or something like that as the asteroid “crashes through” the atmosphere?

How come they also say that most doomsday asteroid/comet movies are unrealistic in that you would never actually see the celestial body falling in the sky to kill you? Supposedly, you would already be dead before a really huge asteroid even hits the earth. You wouldn’t be able to see your last moments looking up and being like “Oh hey, there it is”
I just have trouble picturing how and why that happens.

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8 Answers

Seek's avatar

Pour a small pile of table salt into your hand. Now blow on it.

What happened to the salt?

PhiNotPi's avatar

It is true that the Russian meteor did not actually hit the ground. The meteor exploded during reentry because of the the intense heating and air pressure caused by reentry. This explosion occurred roughly 18 miles in the air, and was 20–30 times more powerful than the atomic bomb dropped on Hiroshima. It was the shockwave from this explosion which caused all of the damage.

This isn’t the first time this has happened. In 1908, an even larger event occurred over Siberia. That explosion, also in midair, was 1000X more powerful than Hiroshima.

CWOTUS's avatar

For a really destructive “modern” asteroid, check out the Tunguska event. The Wikipedia article has a lot of text, and you can search for images, too that will give you a very graphic view of what “a small asteroid or comet” can do to Earth.

stanleybmanly's avatar

The destructive power of an asteroid is easily appreciated if you just visualize a large mass (say the size of your house) traveling at several times the velocity of a bullet. Remember that both the earth and the asteroid are already hurtling through space at velocities measured in miles per second! If the paths of the 2 objects intersect, the earth’s attraction would INCREASE the speed at which the asteroid would approach our planet. It isn’t true that you couldn’t see it coming. If you knew where to look, and had the proper telescope, you could probably watch the approach for days depending on the size of the asteroid. If you were watching with your naked eyes when the thing hit the earth’s uper atmosphere, you would be permanently blinded as your optic nerve was fried by the intensity of the light, but the thing would be traveling at a speed so great that it would have struck the earth before you were aware that you’d been blinded.

kritiper's avatar

Random chance.
If you were directly in front of one that was going to hit the Earth, and not explode in air, it would kill you instantly with the shock wave that it’s incredible speed creates just ahead of it. But you would be smashed to smithereenies is the following instant so what exactly killed you would be moot. If you are off to the side the shock wave it leaves in it’s wake (like the wake a boat leaves in the water) will kill you by concussion, like a bomb or heavy artillery shell blast.

LuckyGuy's avatar

Purdue University has an online simulator/calculator called Impact Earth! that you can use to experiment with various asteroids and see their predicted effects. You can change size, material, velocity, target, etc. and it will tell you energy, global damage, crater, seismic effects, air blast, thermal damage, etc. You’ll love it.
Chicken Little was right!

Bill1939's avatar

Consider catching a baseball tossed underhand and one thrown overhand. The difference of the impact upon your gloved hand is a function of its speed. The power of an asteroid is the product of its mass and velocity.

ScottyMcGeester's avatar

What fascinates me though is how grand the shockwave can be hundreds of miles away. I saw some documentary on them and they said that a formidable asteroid would decimate Washington DC even if it hit NYC. But now that I’m realizing just how fast they are going, it’s no wonder.

@stanleybmanly I see. So now that I think about it, the movie “Seeking a Friend for the End of the World” really has the best depiction of what an asteroid impact would feel like? I probably just ruined it for anyone who hasn’t seen it but it’s not like it’s a huge spoiler. But basically at the end it’s kind of like that – a boom and a flash of light and cut to black.

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