[meteorite-list] Meteorites and sulfurous odors

[Mike Fowler]

> Regarding the reports you mentioned about historic falls, I  
> wouldn't take
> the assertions there to seriously. As we all know, meteorites fall  
> cold, but
> nevertheless the old reports tells the stone was to hot to tuch, it  
> glowed 3
> days, the ground was hot and so on...
>
>
> Best!
> Martin


Hi Martin,

I have to strongly disagree.  First of all, who says we all know  
meteorites fall cold?  I guess you're saying that all the accounts to  
the contrary don't count?
What about the piece of Portales Valley that melted into the tarp it  
fell on?

Secondly, I'll grant you the possibility that meteorites may "fall"  
cold, but after they strike the ground they may not be cold any  
longer due to the kinetic energy of motion being instantly converted  
the heat.  Obviously this applies to heavier stones more than small  
ones.  A walnut sized meteorite with a correspondingly slow terminal  
velocity would likely be cold both falling and after landing.  The  
larger the stone, the less likely this is to be true.  When it comes  
to irons, there are two additional factors.  One is the higher  
terminal velocity for a given weight, due to the higher density.  The  
second is that upon impact much more of the kinetic energy is  
converted to heat, and less is dissipated in crushing, as irons don't  
crush like stones might.  Think about striking an anvil with a hammer  
or a stone.
The hammer will get hot, the stone won't.

I think if you examine the historical accounts you will see that  
accounts of cold meteorites almost always refer to small ones and  
that accounts of warm or hot ones more often refer to much larger  
pieces, or irons.

Although I'm confident of my reasoning, I don't remember reading  
anywhere of a similar explanation.

Mike Fowler
Chicago