[meteorite-list] Zig zags and spinning

From: MexicoDoug_at_aol.com <MexicoDoug_at_meteoritecentral.com>
Date: Wed Jun 30 15:56:53 2004
Message-ID: <111.340c0059.2e1474fc_at_aol.com>

Dear list,

Sounds like we are talking about two different phenoma here: rotational
spinning and relative translational displacement, or zig zagging. There is a third
one to consider, too, spiraling. Spiraling traces zig zagging in that brief
moment of surprise, if like most viewers, they see it from the side, and not
coming right at them.

There is no reason the meteorite can't spiral or truly zig zag coming down,
something like the random a "skipping" stone a child throws at the water. The
same sort of thing happens as the usually rotating meteorite enters the
atmosphere. If the rotation is like a steam roller you'll likely get the true zig
zag, but if the meteor is irregular enough then you get the two diminsional
spiral version of a zig zag. As the amount of surface area to the air changes
direction and intensity while rotating, the upward frictional force varies,
causing a truer zig zag for the steam roller type spinner, which has one degree
less of orientation than a true oriented projectile that fall in a parabolic
arc. On the other hand, if the spin axis isn't perpendicular to the incident
trajectory (i.e. not a steam roller), you will get a spiral. Either way they
look like gradual zig zags.

I have spoken with witnesses to a bolide who independently described the same
even as a zig zag in one case, and the other a spiral. They did not have any
idea what others reported. They even carefully described to me the sounds
accompanying the spiraling cycles: Just like a puttering jalopy which repeats
itself every few seconds.

If you're in a speeding car and have the pleasure to stick a "karate chop"
hand out the window, held straight out, you can zig zag. If you vary the
"straight out" part you will feel the pressure to spiral.

Harvey in "Find a Falling Star" 1972, was very impressed by cowboy Chharles
M. Brown's reflexes in capturing the Pasamonte, New Mexico bolide on film on
March 24, 1933, at exactly 5:00 PM. Al Mitterling kindly sent me an image of
that picture which doesn't appear in the original edition, though it is
discussed a lot. I have taken the liberty of posting kind Al's image of Brown's photo
at:
http://www.diogenite.com/Pasamonte.jpg
where the zig zag is apparent.

Still, I need to agree with Mike in the sense that the newspaper
sensationalized the whole thing, saying "a fiery object zigzagging across the sky" when
the original actual witnesses' quote is much more appropriate in the same
article: "gradual zig zags". There was a slightly suggested, unintention little
green men aspect of the reporter's description, in my opinion, too.

Saludos,
Doug
Mexico


Portales Valley was spinning when it fell, so I think that if the body has a
strange angled shape, that it can tumble, or spin while falling, I doubt
that it was zig zagging as in changing directions like they suggest.
Mike Farmer
----- Original Message -----
From: "Marc D. Fries" <m.fries at gl.ciw.edu>
To: "Meteorite Mailing List" <meteorite-list at meteoritecentral.com>
Sent: Wednesday, June 30, 2004 10:53 AM
Subject: Re: [meteorite-list] Meteor Reported in Australia


>
> Zig-zagging = tumbling space junk?
>
> MDF
>
> >
> >
> > http://www.abc.net.au/news/newsitems/200406/s1143829.htm]
> >
> > Meteorite reported in southern WA
> > Australian Broadcasting Corporation
> > June 30, 2004
> >
> > The Perth Observatory says it has had reports a meteor has crashed
> > near Walpole in Western Australia's south.
> >
> > Witnesses say they saw a large, fiery object zigzagging through the
> > sky at about 5:30pm yesterday.
> >
> > The witnesses say the object left a trail of thick smoke and then
> > they heard a bang.
> >
> > The observatory says it appears the object was travelling somewhere
> > between Perth and Albany in a south-south easterly direction.
> >
> > Walpole resident Heather Burton was in her backyard when she saw the
> > object.
> >
> > She says it was unlike a normal shooting star.
> >
> > "A shooting star usually just goes straight across or straight down
> > - this one had these gradual zigzags just coming down," she said.
> >
> > Alex Bevan from the WA Museum says the reports indicate the
> > sightings were the result of a fireball generated by a meteorite.
> >
> > "We're certainly picking up reports of a bright fireball and sonic
> > phenomena associated - I'm absolutely sure - with the fall of a
> > meteorite," Dr Bevan said.
> >
> > Dr Bevan says it will be difficult to find where the meteorite landed.
> >
> > "Unfortunately there doesn't seem to be as many observations, so
> > actually pinning down where the object landed might be a bit
> > difficult and in that area, the vegetation might mean searching for
> > it would be difficult," he said.
> >
> >
> > ______________________________________________
> > Meteorite-list mailing list
> > Meteorite-list at meteoritecentral.com
> > http://six.pairlist.net/mailman/listinfo/meteorite-list
> >
>
>

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