[meteorite-list] Fire caused by meteorites.. Is it possible?

From: lebofsky at lpl.arizona.edu <lebofsky_at_meteoritecentral.com>
Date: Wed, 29 Aug 2012 16:21:07 -0700
Message-ID: <fda930802db97029e0c773470527c984.squirrel_at_webmail.lpl.arizona.edu>

Hi Chris and Gary:

Comets can be "hot" (actually warm) relative to the ices in them, so we
are still talking about temperatures well below the melting point of
water, at least at the distance of the Earth. Even though the ices, when
mixed with dark material (carbon, for example) could potentially get warm
thanks to solar heating, the ice will sublimate (turn from solid to gas)
and keep the temperature down (essentially the same as evaporative
cooling).

Larry

> Sorry, but that's just crazy. A meteoritic body that strikes the ground
> at terminal velocity, as virtually all meteorites do, cannot be hot
> enough to start a fire. It doesn't matter what it's made of. And in
> fact, there is virtually no evidence supporting the idea that cometary
> bodies produce meteorites. And finally, comets are not hot. The
> temperature of a body in space depends on the ratio of absorbed to
> emitted energy. Close to Earth, bodies are mostly on the cool side-
> freezing or less- with the warm ones still nowhere near hot enough to
> start fires. Of course, after falling through the atmosphere for a few
> minutes, we expect most meteorites to be quite cold on impact- something
> that has been observed.
>
> Chris
>
> *******************************
> Chris L Peterson
> Cloudbait Observatory
> http://www.cloudbait.com
>
> On 8/29/2012 3:43 PM, Gary Daniels wrote:
>> If the meteorite is a comet fragment, then there's no reason it can't be
>> hot
>> enough upon impact to start a fire under the right conditions. Recent
>> evidence has shown that some comets are hot and dry not icy and some
>> also
>> have gas jets on their night sides which astronomers have theorized is
>> only
>> possible if they are somehow transferring (and storing) heat in their
>> interiors. If a comet in space can store heat then a fragment of one
>> should
>> have no problem storing the heat created when entering the atmosphere.
>> If
>> such a meteorite landed in the right conditions (dry grass, for
>> instance)
>> then a fire could be started easily.
>>
>> I've seen grass fires start from very hot lawn mowers (no sparks, just
>> heat)
>> when the grass was extremely dry and there was a slight breeze to fan
>> the
>> flames. I've also seen grass fires start from overheated car engines on
>> the
>> side of the road (in high, dry grass.) So I see no reason why a comet
>> fragment/meteorite couldn't cause a fire under similar circumstances.
>>
>> Whether there are any actual recorded instances of such is an entirely
>> different matter. :)
>>
>> -Gary Daniels
>>
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Received on Wed 29 Aug 2012 07:21:07 PM PDT