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Re: impacts are cool!



Augustus T. White wrote:
> 
> Peter Von Sholly wrote:
> 
> > What if the impact(s) were/was in the ocean?  Which the odds would seem to
> > favor.
> 
> It wouldn't make any difference.  My calculator is AWOL, but we can do
> some order-of-magnitude math for a really impressive strike.  Imagine a
> large, 10km object with a modest density of 1.5 g/cm3 impacting the earth
> with a velocity of 10 km/sec.  The mass comes to something like 7.5 x
> 10(17) g.  v-square is 10(12) cm2/sec2.  Kinetic energy is thus on the
> order of 4 x 10(29).  This is enough to  vaporize 4 x 10(27) cm3 of cold
> seawater, if I haven't slipped an order of magnitude somewhere.  Even the
> Marianas Trench wouldn't slow the sucker down measurably.  In fact, this
> is roughly enough energy to boil a volume of water the size of Mars.  It
> would vaporize rock well into the mantle no matter what was in the way.

This can't be right; that much water is the entire Atlantic basin. 
That's not mass extinction, that's the end of life as we know it.  You
think frogs will survive that?  Turtles?  Crocs?  I don't think so.
 
> Actually, I think the Chicxulub object was smaller -- which is a damned
> good thing.

Or the math is off.  The crater's only a couple hundred kilometers in
diameter even by the largest estimates, which is a heckuva lot smaller
than Mars.

Chris