OFF: The dangers of Cosmic Rock

[K Henderson]

B&C said...

>> They'd have to start by investigating asteroids and comets to figure out
>> HOW to defend against them. Real life ain't Hollywood and even if we did
>> build the capability to nuke 'em far out enough to have an effect, it'd
>> almost certainly make things worse in some cases as it'd alter one big
>> bang somewhere into thousands of medium bangs everywhere.
>
>Plonking a moderate sized asteroid into the Pacific would be a bit of a
>bugger. Having rocks the size of buses crashing into your back yard would be
>a bigger bugger.

Actually, big asteroids hitting oceans are the bigger worry.  'Cause hitting
a random spot on land is very unlikely to be a heavily populated area.  But
even a moderately sized asteroid hitting the ocean can cause a very large
tsunami that would hit many coastal cities in a radial pattern from the
impact site, with residents possibly unawares.

And if you get one of those wonderful 10km asteroids, ie., as big around as
the ocean is deep...look out, another extinction event.  Of course, that
only happens every 60 million years or so, but Earth's geologic and biologic
history is much more defined by 'punctuated equilibrium' than by the theory
of slow, gradual change that the Earth Sciences began under.  Hence, the
term 'neo-catastrophism.'  And now the recent concept of 'snowball Earth'
(that has a fair amount of undeniable evidence), where the global ocean was
thought to be completely frozen over to 1km deep (even at the equator) is
another example of very sceptical scientists accepting such possibilities.
And the idea that the end of the snowball Earth (~600 ma) being just before
the 'Cambrian Explosion,' ie the onset of multicellular life, is intriguing
as well.

So, yes, you can call me a 'neo-catastrophist' but I'd hardly say I was an
alarmist.  But the fact is that natural continental-scale disasters can only
occur from something like a bolide impact (as opposed to nuclear war, or
biological outbreak - something human-induced likely).  There's a limit to
what area and degree a volcano, earthquake, or storm can affect, which is
far below that which an impact can cause.  Earthquake's have a natural limit
of 8.5 or so, whereas bolide impacts are potentially 10's or 11's I think
(and each unit is a factor of 10 roughly, so...).  And climate change, while
a nuisance, is not so necessarily catastrophic even if rapid (which can
happen) - not hard to 'run' from rising sea level or encroaching glaciers or
changing biozones, though expensive certainly.  Humans can live and adapt to
most conditions anywhere on the earth...they'd just have to move around.

So of course I think Spacewatch is underfunded, and SDI overfunded.  :)

Low probability, massive potential.

Grakkl (FAA), non-alarmist and Supertramp supporter, and unconvinced that
the Chicxulub impact 65 ma (which certainly seems 'real') really killed off
all the dinosaurs (and everything else), who seemed to already be declining
before it happened.

ObCD: Supertramp - Crime of the Century

P.S.  Tunguska (1908) didn't actually hit the earth, but exploded about 4 or
5 km above it I think.  But then, those 'impacts' actually widen the area of
destruction and are more dangerous over land.  For the ocean (where the
tsunamis are the real concern) I imagine that exploding fireballs are less
damaging but not sure about that.  Although the reason that they didn't find
anything big and heavy in the center of the Tunguska 'crater' wasn't just
because of it not truly impacting...there's nothing in the center of the
Barringer Crater in Arizona either and that thing actually hit.  The things
just vaporize dontcha know.