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Re: (meteorobs) Meteorites and Terminal velocity
Hi Dave, George,
The "glow in the dark" has been reported a number of times notably with
irons. It need not have to do with radiating heat - Spratt some years ago
proposed an incandescent effect through recombining ions on the irons
surface, a form of natural thermoluminiscence.
Something I would like to offer as a source for some warmth with fresh
falls, is the decay of very short-lived radioactive nuclei formed by cosmic
irradiation while the stone was still in space. Perhaps the decay could
generate some warmth up to a point that it is notable by the touch directly
after the fall. Perhaps this could generate some of the reported
luminiscence. Please note, this is pure conjecture. I never thought of that
before this discussion on meteorobs started - ought to ask this to one of my
professional meteoriticist friends!
Reheating evidence in meteorites certainly has been searched for.
There's no evidence from meteorites that heating effects altered the
material for more than a few millimeters below the surface. In normal irons,
a profound reheating would destroy the Widmanstatten patterning they
display. In stones, for example chondrules would be lost in such a case.
Strong heating to deep depths into the meteorite therefore did not occur.
I would like to point out also that there is no authenticated case of a
meteorite hot enough to be able to start a fire - while many landed into
matter well combustable, e.g. Spratt gives the example of the Forest City
landing in a haystack.
- Marco Langbroek
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