[meteorite-list] fireball over midwest

From: Chris Peterson <clp_at_meteoritecentral.com>
Date: Mon, 5 Feb 2007 16:32:37 -0700
Message-ID: <058501c7497d$ebc1e140$2721500a_at_bellatrix>

A few general observations about witness reports, based on looking at a
few thousand over the years:

-People can't judge elevation. An object 10-20? above the horizon will
often be reported as 45? or higher.

-People can't judge time. A sonic boom that occurs several minutes after
a fireball will usually be reported as less than 30 seconds.

-People don't see things overhead, they see things on the horizon. With
nearly every fireball I've tracked, the majority of reports come from
100-200 miles from the path. Relatively few witnesses are under the
path.

-Comparisons to planes crashing, and references to objects hitting the
ground nearby, usually suggest a fireball 100-200 miles distant.

I've now seen quite a few more reports, and think my original assessment
remains reasonable- this was a fairly short ground path (~100 miles),
beginning south of Davenport and ending north of St Louis, dropping at a
moderate slope (>30?). The St Louis reports are just right for something
that ended 50 or so miles north of the city.

If I were out hunting for meteorites (and with the multiple reports of
sonic booms, there's good reason to expect them), I'd be looking for
witnesses in the towns around Jacksonville, IL. Find people who saw an
overhead terminal explosion, and find people who heard sonic booms. That
will put you in the right area.

Chris

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


----- Original Message -----
From: "Sterling K. Webb" <sterling_k_webb at sbcglobal.net>
To: "Chris Peterson" <clp at alumni.caltech.edu>;
<meteorite-list at meteoritecentral.com>
Sent: Monday, February 05, 2007 1:21 PM
Subject: Re: [meteorite-list] fireball over midwest


Hi,

    If it had a 45-degree angle of descent at Champaign
or Beardstown it would intersect the ground at a distance
south of the observation equal to its altitude at the point
of observation. I recall a longish thread some years ago,
in which Rob Matson discussed the mathematics of
"angle observation" from the ground and demonstrated,
I believe, that determining the actual angle is impossible
without multiple observations, however detailed any one
observation may be.
    With sightings from Appleton, Wisconsin to Cape
Girardeau, Missouri (575 miles), and assuming it lit up
at 60 miles altitude and dropped to zero in 575 miles,
produces a 6 degree angle of descent in the "straight-line"
approximation. Of course, it isn't a "straight" line...
    A 100 mile descent from 15-20 miles altitude from
Beardstown would bring it down north of St. Louis,
in my backyard literally (goes to look for craters). A
100 mile descent from 15-20 miles altitude from Lewistown
would bring it down 20 miles inside Illinois. Today's
newspaper accounts in St. Louis don't sound like
local Missouri witnesses saw something on their far
Northern horizon, which would be too cluttered to
see within 10 degrees of the horizon almost everywhere:

    "The St. Louis Post-Dispatch reports that
calls flooded 911 operators and area police
departments, the Missouri Highway Patrol
said. Callers described the spectacle in various
ways, some saying it looked like a plane crash and
others calling it a ball of fire in the sky."


Sterling
Received on Mon 05 Feb 2007 06:32:37 PM PST