[meteorite-list] Determining fall rate from falls observed

From: Matson, Robert <ROBERT.D.MATSON_at_meteoritecentral.com>
Date: Thu Apr 22 10:16:31 2004
Message-ID: <AF564D2B9D91D411B9FE00508BF1C86901B4EC3A_at_US-Torrance.mail.saic.com>

Hi All,

Tracy asked:

> Considering that there has been a scientific presence on
> the Antarctic ice cap for the past 30+ years, a good place
> to start might be: How many witnessed falls are there
> from Antarctica?

I would guess none. The greatest human presence is during
austral summers, when you have perpetual daylight, so only
the very brightest bolides would be noticed. More importantly,
the only large concentration of people is at McMurdo, so the
only falls likely to be seen would be within a couple hundred
miles of McMurdo.

Only a very small fraction of earth's meteorite falls are
observed. Ignoring the ~70% that are missed because they
occur over the ocean, you still have vast regions of earth's
land mass that are very thinly populated (Gobi and Sahara
Deserts, Greenland, northern Canada, Australian outback,
Siberia, etc.) Factor in the % of time that people are
outdoors, the probability of clear skies, and account for
areas with very obscured viewing (e.g. forests), and I bet
you're left with a number less than 1%.

It also wouldn't surprise me if a significant fraction of
meteorite-dropping falls were not only unobserved but
unobservable. No one is going to see a magnitude -4 bolide
in broad daylight, and yet this might be all that you could
hope for from a tiny stone of a gram or two.

--Rob
Received on Fri 08 Aug 2003 10:26:57 PM PDT