Sterling's calculation was on 12/9/2000. I think I pointed out back
then that the calculation he did is not for the total number of falls
per year... it is the total number of stones that fall per year. At
least that is what it seems to me. I'm not sure what the average
number of stones per fall is, but it must be >10 (Holbrook alone
brings the average to over 10 even if all the other known falls had
only 1). So I'd like to challenge him to recalculate the number of
falls with this in mind.
Jeff
At 09:35 PM 10/16/2009, Sterling K. Webb wrote:
Hi, Ted, Greg, Gary, List,
Are we onto something here?
Well, yes, we are. One data point we'd really
like to have is how many meteorites fall yer year,
the annual flux. To determine it, all we have to do
is to stake out a patch of perfectly cleared planet
and recover and count all the meteorites that fall
there for several centuries or millennia.
Not so convenient, though... Since the fall of
meteorites is a random process, the total area of
the "sampling patch" does not have to be contiguous.
It can be many millions of smaller patches scattered
all over the planet. You can even move them around
randomly -- doesn't affect the accuracy of the final
calculation of the "impact cross-section of the Earth."
That "sampling patch" is CARS (and trucks, and
other vehicles). We can get a good idea of the number
of them year by year. We can closely estimate the mean
geometric cross-section of the targets. And the "lossiness"
of the experimental data is reduced by the fact that
people tend to notice when their shiny pickup truck is
holed by a meteorite!
I did all that sophisticated arithmetic ten years ago
and published a paper with the results, exclusively to
this List (which is why nobody's heard of it). The figure
widely published back them was the MORP rate of
25,530 falls per year, although Zolenski and Wells
argued in 1988 that it could be much higher:
http://adsabs.harvard.edu/full/1990amss.work...91Z
The fall rate that I calculated from this method was
approximately 78,000 falls per yesr with a possible error
of 25,000 either way. So few cars get hit. Rob Matson
chimed in that his personal estimate was a minimum
of 80,000 per annum. From that rate, I predicted (in1
Dec., 1999) that there would be at least one car hit in
the decade 2000-2009 and a better-than-50% chance
it would be two.
It seems to be two (and just in time).
That was Novemeber or December of 1999, and as we
close out 2009, Grimsby appears to be the second (Worden
in 2002 was the first). Getafe (mentioned earlier) is classed
politely as a pseudometeorite. I allowed for the increase in
the number of cars in time, based on the 1990's sales rate
increases.
.
I thought that this idea of mine was, as they say,
"methodologically sweet." I was unreasonably proud of
being so clever until I discovered this paper by Ben Hur
Wilson, entitled "A method of estimating the absolute
number of meteorites," published in 1940 in the old
POPULAR ASTRONOMY, Vol. 48 (p. 366):
http://adsabs.harvard.edu/full/1940PA.....48..366W
which contains the essence of the method. A new
idea is hard to come by.
However, Wilson based his numbers on observed falls
in specific areas which, in 1940, was scanty data. He
concluded there were 250 falls per year for the entire
planet!
Nininger disagreed violently with this; he thought
there were 500 meteorite falls per year (between 1 gram
and 1 kilogram), perhaps as many as 1,000 and cited
some of his own statistics from Kansas finds.
It seems that the more data we get, the faster they fall.
Sterling K. Webb
---------------------------------------------------------------------------
----- Original Message ----- From: "Ted Bunch" <tbe...@cableone.net>
To: "Gary Fujihara" <fuj...@mac.com>; "Greg Stanley"
<stanleygr...@hotmail.com>
Cc: <meteorite-list@meteoritecentral.com>
Sent: Friday, October 16, 2009 4:47 PM
Subject: Re: [meteorite-list] Grimsby family shows off visitor from space
Apparently, meteorites seek out cars much like tornadoes seek out trailer
parks. Are we onto something here?
Ted
On 10/16/09 11:31 AM, "Gary Fujihara" <fuj...@mac.com> wrote:
Wow! Another car-smashing hammer like Bendl (1938), Peekskill (1992),
Getafe (1994)!
gary
On Oct 16, 2009, at 8:22 AM, Greg Stanley wrote:
All:
Take a look. Looks like the real deal. A hammer!
Greg S.
http://beta.stcatharinesstandard.ca/ArticleDisplay.aspx?e=2133932
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Yvonne and Tony Garchinski are the proud new owners of five
tiny meteorite fragments.
They also have a new windshield, after the space rock smashed into
their
Pathfinder three weeks ago.
"I thought it was vandalism, for sure," said Tony Friday as dozens
of reporters converged on his west Grismby home. "Who thinks a
meteorite
is going to crash-land on your car?"
The golf ball-sized fragment is likely part of a larger meteorite
that lit
up the skies of southern Ontario
Sept. 25.
The fireball was first picked up by cameras operated by the
University of
Western Ontario's physics and astronomy department 100 kilometres
above Guelph
as it streaked southeastward at a speed of about 75,000 kilometres
per hour.
Scientists released that footage Oct. 7 and began searching a
12-square-kilometre area near Grimsby
where they thought the meteor fell.
Only after seeing the footage on television did the Grimsby family
realize their car-bashing
vandal might instead be an alien invader.
"We filed a police report and everything," said a laughing Yvonne,
who held out the tiny silver and black space rock pieces for
reporters to see
Friday.
After reading up on the meteorite search, Yvonne called Phil
McCausland, an
astrophysicist at the University
of Western Ontario, who
verified the tiny rocks were out of this world.
"They're probably the oldest rocks that you or I or anyone else are
every going to hold," McCausland said. "it's pretty exciting."
The Garchinskis own the window-smashing space pebbles, but they've
agreed to
loan them to university researchers for three months.
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AstroDay Institute
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(808) 640-9161, fuj...@mac.com
http://astroday.net
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Dr. Jeffrey N. Grossman phone: (703) 648-6184
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