[meteorite-list] Stardust SRC Hot to the touch?

From: Chris Peterson <clp_at_meteoritecentral.com>
Date: Wed Jan 18 15:51:51 2006
Message-ID: <02a201c61c70$fa9b8990$f551040a_at_bellatrix>

Dave-

The interior temperature of the parent body will likely not be extreme. From
a practical standpoint, space has no temperature. A body absorbs energy from
the Sun, and radiates it to space (with a background temperature of a few
kelvins).

An iron body will probably have a warm temperature when it encounters the
Earth. Iron is a very efficient absorber of long wavelengths, which make up
about half of the output of the Sun. It is a much less efficient radiator.
An object that hits the Earth will likely have spent a reasonable time at a
distance of 1 AU from the Sun. Think how hot a piece of iron gets sitting in
the Sun.

A stony body will be cooler, because it doesn't absorb radiation as
efficiently. Its interior will probably be somewhat colder than freezing-
but still not extreme from the standpoint of human touch.

None of this matters much for typical small meteorites (up to a few tens of
centimeters). At that size, the convective cooling experienced while falling
through cold air at ~100 m/s will largely determine the final temperature.

You might want to search back a year or so in the archives. This was
discussed in detail, complete with various solutions to the Stefan-Boltzmann
equation.

Chris

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


----- Original Message -----
From: <dfpens_at_comcast.net>
To: "Chris Peterson" <clp_at_alumni.caltech.edu>; "Meteorite Mailing List"
<meteorite-list_at_meteoritecentral.com>
Sent: Wednesday, January 18, 2006 12:55 PM
Subject: Re: [meteorite-list] Stardust SRC Hot to the touch?


> Has anyone considered that a very cold object will also "burn" your hands
> and thus feel hot. Try picking up something that has been in a tank of
> liquid nitrogen and try to tell if it is hot or cold.
>
> A meteorite travelling for eons in near absolute zero should have an
> interior temperature very very cold. Afterall, it only spends a few
> seconds going through an atmosphere where friction can supply any energy.
>
> Any thermodynamicists out there?
>
> Dave
Received on Wed 18 Jan 2006 03:51:39 PM PST