[meteorite-list] Burst of Meteors Seen Near Finland / Correctionto directions...

From: Bjørn Sørheim <bsoerhei_at_meteoritecentral.com>
Date: Thu Jul 15 11:47:33 2004
Message-ID: <40F9764A_at_epostleser.online.no>

Hello Marc,
I don't think that your anticipation is correct.
In fact Phil Bagnall from England, formerly, maybe still?
on the list has a special page on his website about spiraling
meteors.
Personally during the surprise -pre 17 hours - of the Leonids
in 1998, I saw one strong meteor, maybe -8 mag., that was split
in two AND both of them giving of strong light and both most
clearly corckscrewing just as the smoke was leaving the head
and backwards!
That was when my interest in spiraling meteors was born, by
the way... :-)

I posted this to this list and the meteor list, but nobody
seems to have made a similar observation. Very few people saw
that outburst I believe. But as Phil Bagnall writes on his page,
observations of spiraling meteors pops up now and then.
Of course such motion is hard to see in the more common,
less bright meteors.
Maybe the fast Leonids (71 km/s) are more prone to spiral,
though I have seen a lot of Leonids, but just one (two :) )
that was indeed spiraling.

Bj?rn S?rheim

>===== Original Message From m.fries_at_gl.ciw.edu =====
>Howdy Bjorn
>
> We do get to
>catch meteors in the act on a regular basis at night, and to the best
>of my knowledge no one has ever seen a nighttime meteor trace a
>corkscrewing path across the sky.
> Is this correct? Comments?
>
>Cheers,
>MDF
>
>
>> By the way, a more updated thery of corckscrewing follows here:
>> The supersonic speed of the meteor - several km/s upto ~72 km/s -
>> will create a cavity - a near vacuum - in the wake of its
>> flightpath, inside its shockfront.
>> Very shortly (~momentarily), the air will rush in to fill the
>> cavity from all sides, like what is happening in a tornado e.g.,
>> or in a kitchen sink as the water flows out. This will create
>> a spiraling motion of the fluid, water or air in these example
>> cases.
>> (Is the turning direction determined by the particular location
>> in one the two hemispheres of the Earth in the meteor case,
>> by the way??)
>>
>> The smoke coming out of the melting meteor is subsequently
>> seized by the spiraling motion of the inward rushing air,
>> thus voila - a corckscrewing meteor is created.
>> Is this accepted or not by current knowledge?
>>
>> Bj?rn S?rheim
>>
>>
>>
>>
>>>===== Original Message From Pekka Savolainen <pekka.savolainen_at_dlc.fi>
>>> =====
>>>Please, ignore my former e-mail, made some mistakes with
>>>directions...:-( These should be more correct.
>>>
>>>
>>>
>>>Hello, Bjorn and the list,
>>>
>>>the direction was (or at the moment we suppose, it was) about from
>>>west / north-west to east / east-south, against Vaasa, Finland. The
>>>angle seems to was quite low, about 30 degrees, and the crossing-
>>>point with the ground is somewhere between Vaasa and Valassaaret
>>>on the finnish coast. So it may be possible, something has reached
>>>the shore of Finland between Vaasa and Valassaaret.
>>>
>>>We don?t have a map yet, but you can at least locate Vaasa from;
>>>
>>>http://worldatlas.com/webimage/countrys/europe/lgcolor/ficolor.htm
>>>
>>>best,
>>>
>>>pekka s
>>>
>>> >
>>> >
>>>
>>>
>>>
>>>Bj?rn S?rheim wrote:
>>>
>>> >Hello,
>>> >Actually my impression is that the corkscrewing is
>>> >caused by the *very* high speed of a meteor, not the rotation
>>> >of the meteorite, if there is rotation at all.
>>> >Think about the corckscrewing you see at the wingtips
>>> >of a jetplane - airliner. The higher the speed the more
>>> >corckscrewing effects.
>>> >
>>> >Anyway, which direction did this object travel? If it was seen
>>> >from both Sweden and Finland it might have reached the shore
>>> >in either countries..
>>> >
>>> >Bj?rn S?rheim
>>> >
>>> >
>>> >
>>> >>===== Original Message From m.fries_at_gl.ciw.edu =====
>>> >>Howdy, list
>>> >>
>>> >> Impressive picture! The trail is twisted in a repeating fashion
>>> that
>>> >>can't just be due to winds - I'd say the meteor corkscrewed its way
>>> >>through the atmosphere. I'm curious - the maximum "survivable" entry
>>> >>velocity for meteorites was calculated a while back (forgive the lack
>>> >>of reference here). Would a twisting, spiraling entry have an impact
>>> >>on the survivability of meteorites? I'm inclined to believe that if
>>> >>the total air resistance vector was divided into an opposing vector
>>> and
>>> >>a sideways vector... would that mean the meteorite could be smaller
>>> >>and survive, or would it have to be larger?? On one hand, the vector
>>> >>magnitude parallel/opposite to the flight path would be smaller, but
>>> on
>>> >>the other hand you'd have a "sideways" vector that would put a shear
>>> >>force on the meteorite. The shear strength of materials tends to be a
>>> >>fraction of that of the bulk material strength, so would the meteorite
>>> >>be MORE likely to break up in a corkscrewing flight path?
>>> >>
>>> >> Thoughts? Comments? Does anyone know if anyone has calculated
>>> this
>>> >>sort of thing before?
>>> >>
>>> >>Cheers,
>>> >>MDF
>>> >>
>>> >>
>>> >>
>>> >>>You can find the pic from;
>>> >>>
>>> >>>http://www.vasabladet.fi/nyheter.asp?katID=1
>>> >>>
>>> >>>text only in swedish...;-
>>> >>>
>>> >>>best,
>>> >>>
>>> >>>pekka s
>>> >>>
>>> >>>
>>> >>>
>>> >>>
>>> >>--
>>> >>Marc D. Fries, Ph.D.
>>> >>Postdoctoral Research Associate
>>> >>Carnegie Institution of Washington
>>> >>Geophysical Laboratory
>>> >>5251 Broad Branch Rd. NW
>>> >>Washington, DC 20015
>>> >>PH: 202 478 7970
>>> >>FAX: 202 478 8901
>>> >>______________________________________________
>>> >>Meteorite-list mailing list
>>> >>Meteorite-list_at_meteoritecentral.com
>>> >>http://six.pairlist.net/mailman/listinfo/meteorite-list
>>> >>
>>> >>
>>> >
>>> >
>>> >______________________________________________
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>>> >
>>> >
>>> >
>>>
>>>--
>>>
>>>
>>>
>>>
>>>Pekka Savolainen
>>>Jokiharjuntie 4
>>>FIN-71330 Rasala
>>>FINLAND
>>>
>>>+ 358 400 818 912
>>>
>>>Group Home Page: http://www.smartgroups.com/groups/eurocoin
>>>Group Email Address: eurocoin_at_smartgroups.com
>>>
>>>
>>>
>>>
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>>
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>
>
>--
>Marc D. Fries, Ph.D.
>Postdoctoral Research Associate
>Carnegie Institution of Washington
>Geophysical Laboratory
>5251 Broad Branch Rd. NW
>Washington, DC 20015
>PH: 202 478 7970
>FAX: 202 478 8901
>______________________________________________
>Meteorite-list mailing list
>Meteorite-list_at_meteoritecentral.com
>http://six.pairlist.net/mailman/listinfo/meteorite-list
Received on Thu 15 Jul 2004 11:47:30 AM PDT