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Re: (meteorobs) Re: March 9th, 2000, Arkansas fireball
There is no record of Peekskill just before it hit the ground, so there is
no way of knowing just how hot is was. It is only a very small surface
region that is ablating when the fireball is visible and the amount of
heat that transfers to the interior is relatively small. The interior
is very cold (can't remember how cold, but well sub zero). The heat
affected region of a meteorite comprises the millimeter or so of
solidified fusion crust, the remnant of the final ablation and about
1cm below that. The interior is not physically affected by the
atmospheric flight. As a meteorite can take a minute or more to fall
to the ground after the ablation ends (the fireball "goes out"), and
the frictional heating is considerably less that the previous temperature
of ablation, the body cools. There is no compelling evidence of a
meteorite ever having caused a fire, and there are many occurrences of
meteorites found soon after fall in dry hay, or on a frozen lake
surface. Whilst some meteorites will transfer more heat to the interior
than others, particularly iron meteorites with very low trajectories that
might ablate for tens of seconds, there is still little reason to
believe normal meteorites could start fires. Big events can start fires
due to the thermal IR emitted from the fireball, but here we are talking
of a very different phenomenon.
Cheers, Rob
Robert H. McNaught
rmn@aaocbn.aaodot gov.au
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