[meteorite-list] Meteorite Questions

From: Walter Branch <waltbranch_at_meteoritecentral.com>
Date: Wed, 29 Aug 2007 19:14:29 -0400
Message-ID: <003401c7ea92$5a7413f0$6101a8c0_at_BranchFamily>

Hello Everyone,

I have had plenty of time recently to ponder things such as meteorites. I
am also alone at home at present and am bored. Would some kind,
more-knowledgeable-than-me soul help me with some meteoritical questions.

For example, why does the rim of meteor crater appear "squared" in some
photos, while in others it appears very round? Perspective? Lighting?
Extremely highly localized tectonic shifting (back and forth)?

Also, why is Tatahouine so green? Olivine? Krylon?

I am looking at a slice of NWA 4664 right now (thank you Eric Olson) and I
don't see any much green. Maybe that one is a bad example because NWA 4664
doesn't even look like at Diogenite!

Also, I have read that some meteoroids travel through space in streams and
impact the Earth simultaneously (i.e., they have already broken up before
they hit the Earth's atmosphere). How can this be? I would think that once
a meteoroid has broken in space (most likely due to impact), minute
deviations of the individual pieces in the initial trajectory would
translate into ever increasing deviations in the individual piece's
trajectory, over time. Unless two pieces were traveling in EXACTLY parallel
lines, over time the pieces would be widely dispersed in space.

Remember comet Shoemaker-Levy 9? It was broken apart by gravitational
forces from Jupiter only a year prior to impact, yet by the time it had
encountered the Jovian atmosphere the separation between the pieces was
wider than the diameter of the Earth! After only a year.

Traveling over eons to make it to the inner solar system, how can a
meteoroid stream stay intact enough to cause a tiny strewnfield on the
Earth? I would not think that the Earth's gravitational field would be
strong enough to do what Jupiter did.

Also, I know I have asked this before but I still don't understand how
researchers can determine cosmic ray exposure ages for a meteorite which
ablated a significant portion of the material that absorbed most of the
cosmic rays and which may have fragmented in flight through the Earth's
atmosphere.

Anyone?

-Walter Branch
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Received on Wed 29 Aug 2007 07:14:29 PM PDT