[meteorite-list] Rock on the ground or not?

From: Chris Peterson <clp_at_meteoritecentral.com>
Date: Sun, 30 Mar 2008 08:17:33 -0600
Message-ID: <03de01c89270$d237bdc0$0a01a8c0_at_bellatrix>

That's a difficult question to answer. The majority of meteorites come
from meteors that are not terribly bright. But mag -4, while technically
a fireball, isn't much of one, and is very common. It's fair to say that
a -4 meteor is a candidate for meteorite production, but I don't know
how to quantify that chance.

If the information you are providing is purely from your own
observation, there's not enough information to make any estimates. From
a single vantage point, the velocity and fall angle of the event are
impossible to determine. It may have been heading nearly towards you,
several hundred kilometers away, or it may have been dropping straight
down 50 km away. There's no way to tell. Finally, from a single
viewpoint you have no way of estimating where the actual fall might be.
Even with many witnesses and camera views, it's usually not possible to
narrow a fall zone to less than many square miles.

The meteors that are most likely to produce meteorites have some common
characteristics. They are slow, usually less than 20 km/s (which is most
likely in early evening meteors). Their entry angles are shallow, which
provides lots of time to slow down while high in the atmosphere, before
the air becomes so thick that a fast object can ablate rapidly ablate
away, or fragment into small pieces that burn up.

Chris

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


----- Original Message -----
From: "Lasse Lindh" <3l at comhem.se>
To: <meteorite-list at meteoritecentral.com>
Sent: Sunday, March 30, 2008 6:44 AM
Subject: [meteorite-list] Rock on the ground or not?


> Hi all
>
> If one sees a meteor fall with a brightness of -4 or brighter, it's
> duration is +10 sec. What is the chances of finding a small rock where
> it suppose to have landed? Is it big enough considering the
> brightness and length of fall. It needs to be said that the angle of
> the fall was around 75-80 degrees, allmost straight down.
>
> Regards
>
> Lasse
Received on Sun 30 Mar 2008 10:17:33 AM PDT