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# What would happen if a 500km asteroid hit earth?

Mon 1 Sep, 2008 10:53 am
Here is a large impact simulation of a huge asteroid hitting earth:

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Type: Discussion • Score: 7 • Views: 10,590 • Replies: 14

littlek

2
Mon 1 Sep, 2008 11:13 am
@Robert Gentel,
That seems to give a good picture of what'll happen, no doubt, some day. But, I want to know more - is the atmosphere gone? The oceans?
cicerone imposter

2
Mon 1 Sep, 2008 11:23 am
We must put things into its proper perspective. If a 500km asteroid hits earth, there's nothing we humans can do to avoid it. Why worry?
littlek

2
Mon 1 Sep, 2008 11:36 am
@cicerone imposter,
i DON'T THINK ANYONE HERE IS WORRYING! (sorry about the all-caps)
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Thomas

3
Mon 1 Sep, 2008 11:44 am
@littlek,
Kris, did you catch the story on "killer meteroids" in National Geographic's August issue? It's not about the specific 150km meteroid in Craven's video. But it's about the general problem, the general likelihood, and very interesting.

http://ngm.nationalgeographic.com/2008/08/earth-scars/stone-text

littlek wrote:
But, I want to know more - is the atmosphere gone? The oceans?

I'm tempted to give it a shot, but this is exactly the kind of physics calculations where I would embarrass myself by putting decimal points in the wrong places, confusing signs, and the like.

Anybody up for calculating the kinetic energy of a 150km brick hitting at about 50,000 mph? Anybody up for calculating the volume of the oceans, and now much heat it takes to evaporate that much water? The calculation isn't hard, just tedious. The kind of calculation that's perfect for other people to do.

JTT

0
Mon 1 Sep, 2008 11:45 am
@Thomas,
I did a quick calculation, Thomas. We be toast.
JTT

0
Mon 1 Sep, 2008 01:13 pm
@Thomas,
I'd like to see how the calculations are done, Thomas. I'd even like to just see the formula. These power in these types of events are so far out of our, my, anyway grasp.

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chai2

1
Mon 1 Sep, 2008 06:20 pm
@Robert Gentel,
I hope that woman won't be singing that God awful shrieky **** while it's going on for real.
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dlowan

1
Mon 1 Sep, 2008 06:56 pm
@Thomas,
It's a 500 km asteroid.

I think that might account for a few decimal points right there.

If it HAS already happened a few times in Earth's history, as the film claims, then, unless they all hit before we had an atmosphere and water, such impacts do not make the atmosphere and water disappear.

I guess some might at the point of impact, as part of the ejecta, if it reaches escape velocity.

gungasnake

1
Mon 1 Sep, 2008 09:16 pm
@Robert Gentel,
There is no plausible source for anything like that in the forseeable future. Our own solar system is stable, short period comets and other remnants of whatever was going on 10,000 years ago have been damping exponentially since Roman times, and the nearest thing outside our system which we can even see is four light years away.
Robert Gentel

1
Mon 1 Sep, 2008 09:19 pm
@gungasnake,
Nobody here thinks this is imminent, and it's just a cool video. But hey, if you want to go out of your way to state the obvious have at it.
0 Replies

Sglass

2
Mon 1 Sep, 2008 09:30 pm
@Robert Gentel,
no tsunamis to put the fire out? Merry and I went to the Lyman Museum in Hilo this past week and found out about the force of water. wow.
talk72000

1
Sun 7 Sep, 2008 07:16 pm
@Sglass,
There was a good discussion about the 10 mile diameter chunk that hit the Yacatan Peninsula that most likely wiped out the large non-avian dinosaurs. It depends where the asteroid hits whether lad or sea or borderline coastal area. Under impact loading i.e. sudden collisions, fluids will behave like solids but will give way later. Just do a belly flop dive and you will feel it on your stomach the solidity of water. The earth's crust is about 18 miles thick and under the ocean only 3 miles thick. Heat is a slow process so water will not vaporize instantly. The rock chunk will probably vaporize but it depends on the composition of the asteroid. It could be a loose agglomeration of small stones and a few huge rocks and even ice and dust - a typical comet.

Then there would be an explosion and global shocks as the earth's crust reverberates and the molten interior will be pressured and the weakest crevice in the earth's crust will leak lava or volcanoes will erupt to relieve the internal hydraulic pressure. Tsunamis will form where there are huge sudden displacements of water. We saw how destructive tsunamis are from Indoneasia and Thailand.

The hot shattering pieces of the asteroid on impact with flammables such as trees would start fires for sure; and the high temperature at the impact zone will start flash fires too as well as the lava leakage from cracks in the earth's crust. The 10 mile diameter asteroid was a global killer and a 500 km or 250 mile diameter asteroid will be 25 times more destructive.
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Matremonial

1
Fri 3 Jul, 2015 06:48 pm
@JTT,
Actually, with the technology we have today, we could probably blow it up with 10+ atomic bombs and have ourselves a nice little meteor shower the day after. Nasa's already about to send an atomic bomb to a random asteroid in our belt by spaceship.
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Matremonial

1
Fri 3 Jul, 2015 06:58 pm
@dlowan,
I agree. I mean, honestly, if this did happen, it obviously was not powerful enough to wipe out the ocean, or destroy our atmeosphere. Things like this don't come back. :T

The film claims it happened six times in history..why isn't humanity extinct then? Most importantly, how do we know it happened? We know that an asteroid wiped out the dinosaurs, but not all life. So..it's obvious it can't destroy all life on Earth.

If it happened 6 times, and we only go back to the dinosaurs, then, wouldn't it have destroyed humanity already?

Things like this don't seem real to me. This is why I never believe the Discovery Channel.
0 Replies

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