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Re: (meteorobs) Probabilities of REALLY BIG fireballs...
List:
There is a difference of opinion on this matter between the probability of
impact from a NEO between the neo-catastrophist and the neo
uniformitarianist. Neo-Catastrophist belief that the break up of large
solar approaching comets or asteroids into thousand of parts create a
hazard to Earth every about 20,000 years or so and remain a hazard for
thousands of years - Tunguska is a sample of a piece of the meteorite
stream from the break up of one such comet they say. Neo-Uniformitarians
belief in random hits out of the blue based on statistics which conform to
the 100,000 - 300,000 years to millions years model for 1 - 2 km sizes.
This size is chosen because it is belief this is the size which could bring
civilization to it's knees. Both the English and American schools of
thought claim proof from impacts from the past. Time will tell who is
right.
Personally I do not care who is right only that we plan for the worse case
and hope for the best case. Kind of what we do when we buy insurance.
Victor Noto
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Victor Noto - Kissimmee, Florida USA
vnn2@phoenixat.com
http://www.phoenixat.com/~vnn2/BIGROCK.htm
Website theme quote:
"Life really is a Rock and
the Big Rock giveth and taketh away all life!!"
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> From: Terry Richardson <richardsont@cofcdot edu>
> To: meteorobs@latrade.com
> Subject: Re: (meteorobs) Probabilities of REALLY BIG fireballs...
> Date: Tuesday, February 10, 1998 6:36 AM
>
> Lew writes:
> >
> >But since we're talking about this thread right now, yours is certainly
a
> >question that deserves an answer. So how about it: is there anyone up on
> >the latest NEO statistics, who can tell us the likelihood of a
kilometer+
> >sized dense-material impact within the next few centuries? Can someone
> >hazard a guess as to whether we really know the answer??
>
> This is not my area of astronomy, but I know a little of what the
> specialist say. Ten years ago in my teaching I began to use the statistic
> that we had a near miss from a near earth object (NEO) about once every
> 100,000 years and a hit every 10 to 20 times. That would be a hit every
1-2
> million yeras. Most of these NEO would not be "dinosaur killers" but they
> would still make a mess of things somewhere depending on their size.
> Tungusga could have been our last hit. ANYWAY THAT WAS THE THINKING TEN
> YEARS AGO.
>
> A miss is generally taken to mean the NEO pass within the moon's distance
> or perhaps a little more of the earth. In the last ten years there have
> been several near misses and the old statistics are out the window. The
new
> ones are anybody's guess.
>
>
>
>
> *****************************************
> Terry Richardson
> Department of Physics and Astronomy
> College of Charleston
> Charleston, SC 29424
> 803 953-8071 phone
> 803 953-4824 fax
> http://www.cofcdot edu/~richardt/
> *****************************************
>
>