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Re: What is a Meteorite?
> No one person can ever say they know for sure that we live in a
> stable system, and this applies to meteorites as well. Who's to say what
> is a meteorite, if we may have samples from such possibly diverse
> sources? I am NOT saying anything can be a meteorite, what I am saying is
> that, we should always be openminded, to what could be out there.
> Investigate all rocks that may be meteorites till we are satisfied they
> are, or are not. When we do this we may allow ourselves to discover
> something new, and unique.
Frank,
I think you've hit the nail on the head and are selling yourself short.
(OK, I mix metaphors). By definition, a meteorite is any meteoroid that
survives a plunge through our atmosphere. A meteoroid, of course, is any
natural object in our solar system smaller than an asteroid. (A vague
description, but no one has ever gotten scientists to agree on a
quantitative distinction between meteoroid, asteroid and planet. Check
Webster for the definitions of hill and mountain.) Your observation that
we should not artificially limit what a meteorite is or isn't is very
good.
Technically, even a piece of planet Earth could be a meteorite if it
were spalled off during a large impact, acquired the meteoroid
classification and later returned to Earth. If anyone ever finds a
fusion-crusted piece of Canadian Shield rock it might be interesting to
try cosmic ray aging.
As for the diversity (or lack there of) of meteoritic material, you made
another good observation. The sampling method, random collisions of the
material with Earth in an area as vast as the solar system, is bound to
limit the types of material found. The recent R-chondrite class,
however, shows that new types of material do show up from time to time
and we should not make assumptions about the variety of material off the
Earth.
The problem is akin to us living on Mars and being handed a large quartz
crystal and being told it comes from the third planet. Can we assume
that crystal is representative of that planet? Of course not. Nor can we
assume that the SNCs have given us a full catalog of the composition of
Mars. As you point out, we have been privileged to see a small portion
of the composition of the solar system. There is much more out there,
some similar to minerals here, as well as new minerals we have never
seen.
Humans tend to think that what they know is all there is to know.
Fortunately, nature keeps proving us wrong.
Gene Roberts
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