[meteorite-list] Temperature of meteorites

From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Tue, 23 Nov 2010 14:18:57 -0600
Message-ID: <CEED8BA7C2B541239B71B1F2BFA11EB4_at_ATARIENGINE2>

Some points for the debate:

The rapid flight through the atmosphere is very brief --
1-2 seconds. This is not much time to change the
temperature of the stone.

The rate at which the friction-generated heat is
transferred to the interior of the stone is determined
by the thermal conductivity of that rock, and rock's
thermal conductivity is very low, so low that virtually
none of the heat will affect temperatures deeper
than a few millimeters or a centimeter into the stone.

Most of that heat generated by friction on the outer
surface goes into melting rock which is then is removed
from the meteorite by on-going ablation. The molten
material stripped from the stone takes that heat with it
as it becomes the particles in the trail (which have their
own thermal evolution that does not affect the stone).
Only a small fraction is "wasted" by warming the stone
itself.

That said, thermal equilibrium of the stone is likely
achieved (or nearly) within a very short time once it
lands. Its temperature will be more-or-less whatever
it was before it encountered this obstructive planet.
Apart from some rough treatment of the surface, the
stone's temperature is the same as it always was.

So, what temperature WAS the meteoroid in the many
thousands or millions of years that it orbited the sun?

That depends on what its orbit was, or more precisely,
WHERE its orbit was and its emissivity and reflectivity
and so on. Take a look at the following chart of Meteoroid
Temperature vs. Solar Distance, supplied by MexicoDoug:
http://www.diogenite.com/met-temp.html

It is a model derived from fairly complete and reasonable
assumptions, which were discussed on this List long ago:
http://six.pairlist.net/pipermail/meteorite-list/2005-January/007521.html
This is the first of three parts; follow the links for #2 and
#3. Those with more factors to include are welcome to
refine the model, I'm sure.


Sterling K. Webb
-------------------------------------------------------------------------------------
----- Original Message -----
From: <lebofsky at lpl.arizona.edu>
To: <bernd.pauli at paulinet.de>
Cc: <meteorite-list at meteoritecentral.com>
Sent: Tuesday, November 23, 2010 4:46 AM
Subject: Re: [meteorite-list] Temperature of meteorites


Thanks Bernd:

This will help a lot!

My guess is that "warm" means warmer than the air temperature, but
probably not much warmer than body temperature since even 15 to 20
degrees
Centigrade (125 to 135 degrees F) is considered hot.

Given that some have been said to be frosty, and one always hears that
they are the temperature of space, how many of the "hot" ones might
actually be too cold to handle? Maybe that is the myth! I am very
surprised that anything small that has had a chance to cool down in the
atmosphere would still be to hot to handle on the ground.

I guess I will just have to wait and see my own Fall and pick it up
quickly!

I wish I could find the old Lost City fall picture of the meteorite in
snow. I do not remember seeing any melted snow around it, but it must
have
been warm enough to attract a dog.

Larry

> Good morning Listees, Listoids, Listers,
>
> Here's a copy of something I posted many years ago (maybe 2004).
>
> Cheers,
>
> Bernd
>
> -----------------------------------------------------------
>
>
> Meteorites - warm or hot to the touch?
>
> 01) The Binningup meteorite was recovered within a few minutes
> of the fall and was reported to have been warm to the touch.
>
> 02) Cabin Creek: Three hours after the fall, Mr. and Mrs. Shandy were
> able
> to find the hole and excavate the mass, reportedly still uncomfortably
> warm.
>
> 03) Glatton: was warm, not hot, when first picked up.
>
> 04) Gurram Konda: near the tent some small warm
> stones, which the Sentry has seen falling down.
>
> 05) Juromenha: The mass was said to have been incandescent
> when discovered and still warm when recovered next morning
>
> 06) L'Aigle: Affrighted persons who picked them up found
> the stones to be very warm and smelling of sulfur.
>
> 07) Limerick: It was immediately dug up, and I have been informed by
> those
> that were
> present, and on whom I could rely, that it was then warm and had a
> sulphurous smell.
>
> 08) Middlesbrough: The stone was "new-milk warm" when found, ...
>
> 09) Noblesville: The meteorite was not glowing as it passed the boys
> and
> was "slightly warm" when Spaulding picked it up a few seconds after it
> fell.
>
> 10) Pettiswood: The affrighted horse fell to the Earth, and two boys
> rushed to him in
> terror carrying fragments that Bingley found to be warm as milk just
> from
> the cow.
>
> 11) Pontlyfni: When I picked up the fragment of metal, or whatever it
> is,
> it was warm in my hand.
>
> 12) Rowton: It is, moreover, stated that when Mr. Brooks found the
> mass
> "it was quite warm."
>
> 13) Tsukuba: Seconds later student Ryutaro Araki stopped to retrieve
> a still-warm stone that had fallen in front of his car near Tsukuba
>
> 14) Wold Cottage: Rushing to the spot he found a large
> stone, warm and smoking and smelling of sulfur.
>
> 15) Crumlin: When dug out the object, which had embedded itself in a
> straightdownward
> course for 13 inches, was found to be quite hot, continuing so for
> about
> an hour.
>
> 16) Eichst?dt: The man rushed to the spot but found the black
> stone too hot to pick up until it cooled in the snow.
>
> 17) Hanau: A hot stone the size of a pea was picked up, weight 0.37
> gr.
>
> 18) Harrogate: A hot stone, like basalt, fell accompanied
> by whistling in the air and lightning and thunder ...
>
> 19) Holbrook: One piece larger than an orange fell into a tree in a
> yard
> at Aztec cutting the limb off slick and clean and falling to the
> ground,
> and when picked up was almost red-hot.
>
> Von Achen, who saw them fall, reported that they were too hot to pick
> up. Two accounts state that they became lighter in color after
> cooling.
>
> 20) Luc?: several harvesters, startled by sudden thunderclaps and a
> loud
> hissing noise, looked up and saw the stone plunge into a field where
> they
> found it half-buried and too hot to pick up.
>
> 21) Magombedze: A 10-cm stone weighing approximately 600 gr
> survived the impact intact and was hot to touch.
>
> 22) Menziswyl: The farmers say that the stone fell with the lightning
> and
> shattered when it hit the ground; it was hot when they picked it up.
>
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Received on Tue 23 Nov 2010 03:18:57 PM PST