Re: Need scientific backup for comet impact story I'm writing.

On Wed, 14 Nov 2007 01:48:10 +0000, Chaz wrote:

Hi everyone. I'm writing a story about a comet hitting the Earth. What
I need to happen is a comet will hit the Earth and cause some serious
localized damage but not end the world as we know it. What I need to
know is:

Is this even scientifically possible? I ask because from what I've
already read some say that even a very small object could end all life
on Earth.

Overall effect would depend both on the size and the site of impact.
Comets are not solid bodies and it is likely to break up into smaller
pieces, so multiple smaller impact is the most likely event. Remember
Shoemaker-Levy impact on Jupiter ?

What size would this comet have to be to hit the Earth and not kill
everyone? The size of a car? A house? An office building?

To kill every human being it has to be some kilometers wide. To kill every
living thing on the earth it would have to be several tens of kilometer,
may be even hundreds of kilometers wide. Biosphere extends to several
kilometers down the earth's crust. Vent organisms in deep oceanic
spreading ridges are least likely to be affected.

Are there any circumstances that would make survival more likely? For
example, if the comet hit the North Pole or somewhere with very deep
snow? Would this make any difference at all in the outcome? Would deep
snow or ice dampen the amount of debris flung up into the atmosphere?
What if it hit an inland lake or a swamp?

Hitting Arctic or Antarctic icesheets will release lots of meltwater. That
would cause flood, rise of sea level, etc., thus causing more after effect
than hitting ocean or land. Hitting ocean will of course cause a great
tsunami.

This is going to be a work of fiction but I'd like to make it as close
to real as possible. I'm one of those nitpicky people who likes details
like that. If anyone has any input on this I'd love to hear it! Thanks!

Nobody has any previous experience of such an event. So basically anything
goes.


--
gautam
.