[meteorite-list] Holy crap-- can anyone confirm this? Any, vikingson the list?

From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Sun Jun 11 23:12:09 2006
Message-ID: <002801c68db6$dfd99220$c2e4fb44_at_ATARIENGINE>

Hi, Marco,

    I stand corrected on some, argumentative on others.
The track of the Tunguska Object is hotly disputed; the
observations are inconsistent, with a variety of tracks
reported, even S to N. A dispute, like so much
about Tunguska.
    Fred Whipple, way back in the 1950's, suggested
a fragment derived from Comet Encke (said to be the
origin of the beta Taurids) for Tunguska, long before
the existence of beta Taurids were recognized.
    The little map on the aftenposten item shows a
WSW to ENE track, with an azimuth that points
straight at Taurus rising, assuming their track isn't
imaginary, which it well could be.
    Since the text mentions observations in Finnmark
before impact, and Finnmark is hundreds of miles
west of the Reisadalen, that implied it was visible
there first and suggested, wrongly, a west to east
track. Just jumping at conclusions, as I said, knowing
a lot of it would be wrong. Then I saw the aftenposten
item, whatever that means...
    Yes, the beta Taurid stream is broad and diffuse; they
cover the entire Earth. Do we notice more hits in the
northern hemisphere because we live there, because it
has more people, etc.? I empirically count more big
ones in the northern hemisphere but it could be prejudice
or coincidence or just dumb, I'll grant you that.
    The beta Taurid stream is so broad and diffuse that
the radiant is very imprecise. They last for 30 days. The
"stream" has many varied components, is not well
understood nor mapped, and again, disputed. If it
originates with a Proto-Encke body, it is very old, and
consequently evolved and dispersed. And, of course,
that suggested origin is itself disputed. (Isn't everything
that's interesting?) A retrograde sub-stream has been
suggested; again disputed. Napier and Clube attribute
many events to it (very disputed).
    Of course, this Norwegian object, if there really was
a big object, may or may not have been a beta Taurid.
It was a suspicion from the date, as there seems to a
recent trend in potential beta Taurids of nasty size around
June 5-7, and a decline in the June 30th peak, or so I'm
told, or read.
    There's a seismic trace from two stations in the URL
Darren Garrison posted. It should be possible to
approximate the energy of an impact if there was one,
but the procedures to do so are not common to
seismologists. Lots of folks at Sandia Labs or working
with nuclear bomb detection are familiar with them,
though... They could probably tell us if the impact
energy was as great as 20 kiloTons TNT, if they were
in a talking mood, since that is above detectable
limits, which much lower (2-7 kTons?). The
barometric possibilities are chancier. The energy
could be insufficient for all but local stations.
    Known meteor streams account for only a portion
of the objects that enter the atmosphere. We call the
rest "erratics," as if they were poorly behaved or not
worthy of notice, despite how numerous they are. If
we can assign them to a known group, we can more
easily hypothesize about them, but that is merely
convenient for us. In the real world, anything can
come from anywhere.
    No fallen extraterrestrial object ("meteorite") has
ever been successfully linked to a meteor stream.
None. This suggests very small rubble, dust, and
fluff make up most meteor streams. Yet there are
plentiful evidences of some very solid items in the
beta Taurids (a VW-sized object impacted on the
Moon June 5th, 1972, the greatest impact registered
by the seismic instruments left there). The problem is
that the beta Taurids are so diffuse that identifying
an object as a beta Taurid is problematic with prior
orbital data for the object.
    "The Taurid complex currently includes the Taurid
meteor stream, Comet Encke (the only known currently
active comet in the Taurid complex), "asteroids" such as
2101 Adonis and 2201 Oljato, and copious amounts
of dust. All ten of the numbered asteroids in the Taurid
complex appear to have associated meteor showers
and therefore are likely to be extinct comets
masquerading as asteroids."
    In other words, always a great candidate for the
source of any big impact at this time of year...


Sterling K. Webb
-----------------------------------------------------
----- Original Message -----
From: "Marco Langbroek" <marco.langbroek_at_wanadoo.nl>
To: "meteorite list" <meteorite-list_at_meteoritecentral.com>
Sent: Sunday, June 11, 2006 11:57 AM
Subject: Re: [meteorite-list] Holy crap-- can anyone confirm this?
Any,vikingson the list?


> Sterling K. Webb wrote:
>
> > Compare to Tunguska in date and lattitude
>
> Date okay, but what has latitude to do with it? There is no reason at all
> why atmospheric entry of objects from the beta Taurid stream (if Tunguska
> was related to this stream at all!) would be restricted to high northern
> latitudes. In fact it is not even restricted to the northern hemisphere
>
> > BetaTaurids are daylight fireballs (it was "daylight" there).
>
> The beta Taurid radiant was barely over the horizon (only a few degrees)
> and it was close to local midnight (albeit with midnight sun, yes).
>
>
> > Check sky over Norway (rough radiant on E horizon;
> > anti-radiant on W horizon; they come both ways.)
>
> Wrong. They only come from the radiant and move *towards* the
> anti-radiant.
>
> > Sounds as if fireball went west to east if seen in Finnmark
> > then impacted in Troms. (Tunguska went west to east.)
>
> Again: wrong. Tunguska for what we know of it went southeast to northwest.
> And fireballs from the same source for the Norwegian time and location
> should move northeast to southwest, not west to east.
>
> Besides: the reports so far do really not give any clear clue as to
> direction of the Norwegian fireball.
>
> I am curious to know whether the seismic data point to an airblast or a
> real impact (that is not yet clear to me). Not everything giving of strong
> sonic booms ends on the ground, you know.
>
> - Marco
>
> -----
> Dr Marco Langbroek
> Dutch Meteor Society (DMS)
>
> e-mail: meteorites_at_dmsweb.org
> private website http://home.wanadoo.nl/marco.langbroek
> DMS website http://www.dmsweb.org
> -----
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Received on Sun 11 Jun 2006 08:26:39 PM PDT