(meteorobs) Meteorite pix

[Chris Peterson]

It all comes down to the emissivity of the object. Any object reaches an 
equilibrium temperature based on the balance between the rates the material 
absorbs radiation and the rate it reradiates it.

Meteoroids have an internal temperature that can range from chilly- 
typically tens of degrees below freezing, to quite warm (like a rock sitting 
in the Sun, which is basically what a meteoroid is).

This temperature is hardly affected by a brief ablative passage through the 
atmosphere. Commonly the object breaks up during those few seconds, the 
remaining pieces very rapidly slow down to their terminal velocity, and then 
fall through very cold (-40°C) air for up to several minutes. This is a 
convective process- far more efficient than radiative. So the meteorite 
cools down, unless it is very large and can maintain more of its original 
heat. So your typical small (few kg or less) meteorite is probably going to 
be cooler than ambient in its interior upon impact.

Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com


----- Original Message ----- 
From: <GeoZay at aol.com>
To: <meteorobs at meteorobs.org>; <prospector at znet.com>
Sent: Wednesday, December 03, 2008 10:58 AM
Subject: Re: (meteorobs) Meteorite pix


>
>>>Meteorites have several opportunities to gain heat, first from  the sun
> in space where the sunlight side can reach 120C/248F.  <<
>
> How come the astronauts on apollo 13 complained about it  getting cold 
> when
> everything was shut off? I believe temps got down to around 32  F before 
> they
> finally got  back on earth. I imagine it would have gotten  colder over a
> longer period of time.
> George Zay