[meteorite-list] Tunguska..

From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Tue, 1 Jul 2008 02:03:48 -0500
Message-ID: <05f801c8db48$9cfd18a0$2346e146_at_ATARIENGINE>

Hi, All,

    Mark wrote:
> are we really anywhere further forward explaining it?

    The list of (so-called) possibilities is long. It's a zoo
that contains some really weird critters:
http://www.space.com/news/080630-mm-tunguska-mystery.html
This article summarizes them: asteroids, comets, mini
black holes, antimatter, terrestrial cryptovolcanic gas
eruption, UFO's, and Nikola Tesla testing his Death
Ray!

    Why should Tunguska (apart from the size of the blast)
attract so many whacky and "mysterious" explanations?
The answer is simple. Lack of material evidence.

    If one could have walked around Arizona's Meteor
Crater a century ago or more, many thousands of tons
of evidence abundantly littered the surrounding territory,
making the case for extraterrestrial origin hard to deny.
Despite many claims, no clear and undisputed material
can be identified as a portion of the Tunguska impactor,
no stones, no fragments, not even the microspherules
nor the dust particles claimed to come from it. Only
a big Zero.

    Secondly, there's the lack of a really big hole in the
ground! Or even a very small hole in the ground... No
chunks, no holes -- it's an invitation to fantasy. It's also
an invitation to the reconstructionist tendencies natural to
science. We start hypothesizing and modeling, with or
without computers.

    For example, if the object had been an iron this size
(mass), it would have made it to the ground without
question. If it had been a stone of this size (diameter),
it would have airburst at a much, much higher altitude
than Tunguska's 25,000 to 30,000 feet. You start fiddling
with the models, increase the size, decrease the density,
up the speed a bit, and so forth...

    It's an exercise, because at the end there's no actual
evidential result to compare it to. Some of the "theories"
only work by ignoring some huge chunk of the evidence.
There is a wide-spread and erroneous belief, for example,
that a bolide was not sighted. That is the assumption of
the black hole, antimatter and gas explosion theories.

    On the contrary, A. V. Voznesensky collected such
reports long before Kulik went to Tunguska and estimated
it must have been seen by many thousands of people
even in "empty" Siberia; he collected nearly 100 reports
over a sighting line nearly 1000 miles long. The bolide was,
as you might expect, spectacular, many times brighter than
the Sun and followed by an immense black dust trail that
blackened the sky after the bolide had passed. Whatever
was left to airburst over the swamp could only have been
a tiny fraction of the original object.

    It is worth noting that the climatic cycle of that region
is extreme, from a moderately warm wet swamp in the
summer to... hey, it's Siberia! I discovered that you can
get the weather for Vanavara on the internet. It was 79 F
today; the low will be 55 F; the humidity was 70%; the day
will be 19 hours long, 22 hours if you count twilight. But
last January 10th (2008), the high temperature was -35 F;
the low was -61 F, and it was snowing... The day was
about 4 hours long.

    It was 19 years before Kulik's first trip to the site. IF
there were any stones, how you suppose they dealt with
an annual cycle of 150 degrees of temperature change while
sitting in a swamp? Assuming that they were fragile stones
(and the low airburst suggests that), I think they would be...
hmmm, looks like mud to me.

    What would Carancas look like if we waited twenty
years to go look for it in the river bed and along the
shore?

    There is a great deal of data and observations about
Tunguska accumulated through the years. An example
is the careful mapping of the fall zone. It appears that
rather than one epicenter for the radial pattern of fallen
trees, there are four epicenters around the "telegraph pole"
forest, each with its own radial pattern that, at greater
distances, merges into an overall pattern, suggesting that
there was a last fragmentation of the object an instant
before the terminal airburst.

    Worth looking over is this archive:
http://omzg.sscc.ru/tunguska/index.html
I suggest reading Vasilyev's long article, and there are
two articles by Roy Gallant on this site that are well worth
the time.

    Here is a treasure trove of translated contemporary
witness reports. I am often derided for my interest in
actual data (so inferior to computer models), but this
is a ton of data!
http://www.vurdalak.com/tunguska/witness/witnesses.htm
Thoughtfully posted on the internet by a Black Hole Believer!

    Here's the photos from Kulik's 1938 aerial survey:
http://www-th.bo.infn.it/tunguska/APS-photolist.htm
and a lot more stuff on the Tunguska Home Page
http://www-th.bo.infn.it/tunguska/

    Here's the "tree particle" resin-trapped cosmic dust
argument, for what it's worth:
http://www-th.bo.infn.it/tunguska/papers/pss2.html

    The case for Asteroidal Origin of the object, very well
done -- the sort thing that convinces me as long as I keep
reading; the doubt only creeps in afterward...
http://www-th.bo.infn.it/tunguska/aah2886.pdf

    Think it's a comet nuclei? What is a comet nuclei anyway?
https://openaccess.leidenuniv.nl/bitstream/1887/7074/1/A%26A_330_375_380.pdf

    The 100th Anniversary article in Scientific American:
http://www.sciam.com/article.cfm?id=the-tunguska-mystery-100-years-later
There's a discussion of Lake Checko in there, because it's
the hot new Tunguska topic. I'm waiting to be convinced,
guys. It was 79 there today -- go get a nice drill core of
the meteorite at the bottom of that lake for us... (They
ALWAYS say the meteorite is under the bottom of the
lake or under the floor of the crater or... It's like a case
of Meteorite Fever.)

    The major Soviet investigation in 1961, with 78 scientists,
made this report, originally published in "Meteoritica" (1963):
http://abob.libs.uga.edu/bobk/tungmet.html

    Here's the gas explosion theory interestingly defended.
Shame about that bolide:
http://www.ias.ac.in/currsci/aug252001/399.pdf
and
http://www.chjaa.org/2003/Italy/55.pdf

    There lots of strange theories. Here are some more.
Scroll down about halfway and read about the isotopic
composition of the peat in the swamp at the 1908 level:
http://olkhov.narod.ru/conf98.htm
and a interesting gallery of pictures not to be missed:
http://olkhov.narod.ru/pictures.htm

    You can even listen to the impact. Well, OK, it's a
reconstruction based on the witness accounts, but it's
an interesting idea for something to do if you're an
astronomer and an audio-nut:
http://planetologia.elte.hu/1cikkeke.phtml?cim=tunguska.html

    I left out the UFO pages, Mark. You want
Tunguska solutions? Go crazy!


Sterling K. Webb
-----------------------------------------------------------------------
----- Original Message -----
From: "Mark Ford" <mark.ford at ssl.gb.com>
To: <Meteorite-list at meteoritecentral.com>
Sent: Monday, June 30, 2008 2:22 PM
Subject: [meteorite-list] Tunguska..



Tunguska 100 years today - deserves a mention!

And are we really anywhere further forward explaining it? I wonder.


Best,
Mark
Received on Tue 01 Jul 2008 03:03:48 AM PDT