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Re: Meteor increase worries scientists
I let the scientists fight over their theories and watch to see what settles
out of the dust. In many cases, opposing theories tend to have more in common
than not and it ends up being an ego fight over who is right. Many times each
is partially right. Scientists many times think in black or white, right or
wrong when two theories can actually compliment each other. The spiral arm
theory with a 40 to 140 million year cycle makes sense if you look at the five
major mass extinction (we know of). When you add in the additional 20 or so
minor to moderate extinctions a 30 million year cycle becomes more apparent.
It's quite possible that spiral arm passage and lens passage work as separate
triggers and may even combine their affects at times.
Passage through the galactic lens does not encounter a solid disk, of course,
but it does encounter sufficiently increased densities in gas clouds to affect
bodies out in the Oort cloud (theoretically). The cometary bodies out there
could be up to a light-year or more from the sun and are only loosely tied to
it gravitationally. It would not take an overly massive cloud to affect them
enough to move some Oort bodies (cometoids?) away from or towards the sun.
Estimates are that up to several thousand could be perturbed one way or the
other by one passage through the denser areas of the lens. Some are probably
meteoroid in size, but estimates of Oort cloud body size range into the
hundreds of kilometers and there are estimates of a trillion bodies.
What that might mean to Earth then becomes a function of chance: how many
bodies of what sizes in what orbits. If extinctions are triggered or
exacerbated by major impacts, we may have the evidence of these processes.
Then again, there may be some entirely different process at work. An apparent
cycle to extinctions could be just noise, but there seems to be enough
evidence to support major impacts at the approximate times of extinctions.
There are also dated major impacts that don't appear related to any
extinction. Impacts may very well work with other terrestrial phenomena to
cause extinctions.
Gene
Jarmo Korteniemi wrote:
>
> I for one do not agree with the theory of 30 million years, since it
> still needs some adjustment. The Galactic disk we pass through every
> 30 million years isn't actually a solid plane, is it? And the
> amplitude the Sun has moving up and down isn't actually very big, thus
> the Sun isn't in and out of the disk... as I understand, we are pretty
> much in the disk all the time, just passing through some more dense
> areas from time to time. So the number of extra particles from the
> Oort cloud falling down on the Sun (and on Earth) must be only a few
> meteoroids here and there...?
>
> And since the Sun circles around the galactic core also, we pass
> occasionally a spiral arm of the galaxy... as I understand, it has
> much more stuff in it than what we have around us now, between the
> spiral arms.
>
> So, if this theory were true, we should have some more meteorites
> falling on us every time we pass through the disk and MUCH MUCH more
> when we pass through the spiral arms. And we do not have much evidence
> to suggest that, or do we? And evidence should show also that the
> other planets have had an extra load of meteors falling on them also,
> shouldn't it..?
>
> It's just my opinion... right out of the blue. Feel free to comment.
>
> An article was written about the sublect and can be found at
> http://xxx.sissa.it/abs/astro-ph/?9802174
>
> ===
> /\_./o__ If you doubt anything stated in this message,
> (/^/(_^^' please reply and I will consider your point of
> ._.(_.)_ view... for about two seconds. =)
>
> I'm out of here. Jarmo Korteniemi
> Bye for now. email: eltanin@rocketmail.com
> phone: FI-(0)8-556 11 42
>
> Sacred cows make the best hamburger.
> -- Mark Twain
>
> ---Gene Roberts wrote:
> >
> > Hello all,
> >
> > Regarding the perception of an increase in bolide sightings, it may
> or may not
> > be factual and it may or may not be significant. There is such a
> thing as
> > random clustering and this list has contributed to everyone's
> awareness of
> > incidents. Only time will tell.
> >
> > If you want something to ponder, consider this: Michael Ramphino,
> who, at
> > least in part, discovered the possible 30 million year cycle of
> major impacts
> > has an excellent article in the current Planetary Report from The
> Planetary
> > Society. In the article he points out that one possible cause for
> the cycle is
> > the solar system moving up and down through the galactic lens as it
> rotates
> > around the Milky Way, which causes large cometary objects in the
> Oort cloud to
> > be perturbed inward towards the sun. IF all this theory and
> speculation were
> > true, the solar system has "just" passed through the lens a few
> million years
> > ago, and all those perturbed cometary objects would be showing up
> right about
> > now (give or take a few hundreds of thousands of years).
> >
> > It's all theory, of course, but it's interesting timing in terms of
> species
> > development.
> >
> > Gene
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