From: Eugen Leitl (eugen@leitl.org)
Date: Thu May 09 2002 - 03:54:10 MDT
On Wed, 8 May 2002 CurtAdams@aol.com wrote:
> Well, it could if it came more often than every 100 million years.
> The "oh, this explains mass extinctions" is very iffy, since the
> Cretaceous is associated with a monster asteroid, the mid-Cambrian
It's interesting whether the radiation showers would generate detectable
element transmutation (in the atmosphere and planetary surface), which
would then get enrichened in a sediment striatum.
> with glaciers at the equator, the Permian with a comet *and* a
> cooling earth, and I just saw a presentation a few months ago claiming
> one of the other (Ordovician?) is artefactual. Not much to be explained.
If the shockwave sets one half Earth's hemisphere burning, toasts the
ozone layer, and enrichens the atmosphere with nitrogen oxides, there
you've got a major impact on climate. But we should see impacts of such
giant flashes on the Moon surface, and on other asteroids. Their surfaces
age so slowly, a major event 100 MYears or so ago should be very
detectable.
> Like you, I'm a little skeptical. Space is so huge - even exploding
> stars don't do all that much. Hopefully some informed astronomers
The problem is the energy in the collimated beam, radiated bidirectionally
along the poles. GRBs appear to be distant collapse flashes according to
recent models.
> will put some counterarguments on the table soon.
This sterilization mechanism is certainly something which needs to be
plugged in into the models for rare Earth.
This archive was generated by hypermail 2.1.5 : Sat Nov 02 2002 - 09:13:55 MST