[meteorite-list] Meteorite-list Digest, Vol 36, Issue 28

[Chris Peterson]

Objects in orbit around the Earth reenter close to Earth's escape 
velocity, which sets the lower limit for anything entering our 
atmosphere (the upper limit is set by the escape velocity of the Sun at 
the Earth- it's unlikely that anything we encounter would be faster than 
that). And for the most part, as you note, reentering objects are 
usually in flat trajectories, so they burn much longer, and are likely 
to slow down enough to stop burning before vaporizing. The Air Force has 
a group whose mission is to recover fallen junk.

I'm not sure what you mean by "close to the ground"- anything you saw 
was probably more than 20 miles high, with 50 being more likely. There's 
no way to tell by eye how high a fireball actually is.

Chris

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


----- Original Message ----- 
From: <VisualThinker7 at aol.com>
To: <meteorite-list at meteoritecentral.com>
Sent: Thursday, December 07, 2006 12:17 PM
Subject: Re: [meteorite-list] Meteorite-list Digest, Vol 36, Issue 28


> I'm guessing that 'space junk' is slower because it was in orbit, and 
> as  the
> orbit decayed it entered the atmosphere as a shallow angle. Then, as 
> the
> atmosphere grew thicker, it slowed gradually.
>
> All of the green fireballs I've seen during my years of hiking and 
> camping
> out west were close to the ground. The much smaller and more numerous 
> ones
> further away always appeared white.