[meteorite-list] Cali chondrite fell extremely cold!

[Chris Peterson]

Such calculations are useful to a first approximation, but there's no 
really accurate way to know what the temperature of the parent body was. 
It depends on the spin rate, the albedo, and other things that normally 
are not known with any certainty.

The bottom line is that the interior temperature is probably nothing 
extreme- a few tens of degrees below freezing to a few tens of degrees 
above. The few seconds spent ablating in the atmosphere have a 
negligible effect on the interior temperature. The few minutes spent in 
dark flight have a profound effect on the temperature if the meteorite 
is small, much less if it is large. Even in equatorial regions, most of 
the dark flight will be through air at ~-40°C.

I would expect most meteorites to have an exterior temperature fairly 
near ambient if they are picked up immediately, and probably a bit 
colder than that if they are not recovered for a few minutes (since the 
interior is likely to still be cold). It's worth keeping in mind that 
ambient in most cases is below body temperature, and with the excellent 
thermal conductivity of both stone and iron that means that they will 
tend to feel cool to the touch.

AFAIK _credible_ reports of fresh falls being hot to the touch are quite 
rare. But some objects can be fairly toasty before they enter, and if 
they are large when they fall, or if they don't fragment until quite low 
(i.e. a short period of dark flight) it isn't unreasonable they might 
feel warm or hot if recovered quickly.

Chris

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


----- Original Message ----- 
From: "Sterling K. Webb" <sterling_k_webb at sbcglobal.net>
To: "Alexander Seidel" <gsac at gmx.net>; "Michael Farmer" 
<meteoriteguy at yahoo.com>; <meteorite-list at meteoritecentral.com>
Sent: Saturday, July 28, 2007 9:06 PM
Subject: Re: [meteorite-list] Cali chondrite fell extremely cold!


> Dear Alex, Mike, List,
>
>    Alex said:
>> several posts about this on the list in the past...
>
>    Mexico Doug has done more work on this than anyone
> else I can think of. Go to the website http://www.diogenite.com/
> and click on the item "Meteoroid" in the left-hand menu.
> There is Doug's graph of the space equilibrium temperatures
> for irons, ordinary condrites, and carbonaceous chondrites
> for any distance from the sun...
-list