Re: Comet impact in the Eastern United States - Feasibility of Evacuation

James Nicoll <jdnicoll@[EMAIL PROTECTED]
> wrote:
>	In fact, even if we move the goal posts to mere mass extinctions, 
>there's only one mass extinction that is thought to have been caused by
>an impact and lots of large craters that are not associated with
extinctions 
>at all. Your garden variety flood basalt seems to be worse for the 
>environment and any cooling event that leads to a snowball or slushball
>Earth would also be very bad. 

And didn't Asimov, in one of his science essays, analyze things and figure
out that a comet/large object hit in the ocean would be a good deal worse
for
the entire Earth than one on land would? Land -> large molten area,
crater,
and rock dust all over the atmosphere. Water -> small molten area under
the
water, crater under the water, rock dust _and steam_ all over the
atmosphere:
instant winter for a few years, most mammals die out, etc etc.

>	Sterilization events that any half-way competent SF writer 
>should know about include the Sun's progressive brightening, something
>that should kick the Earth over into runaway greenhouse in the next
>billion years or so, and gamma ray bursters, which in theory could
>have much the same effect on the Earth as putting it in a (very large)
>microwave oven. 

Especially since someone thinks they've just found a possible future one
of
the latter, depending on _how_ exactly aligned the axis of the system is
with
us.

Dave "we just have to put up a 10,000-mile wide lead sheet half a mile
thick
 between us and it ... or possibly tow Jupiter into the correct position
...
 right? Or maybe invoke gravitational lensing" DeLaney
-- 
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