[meteorite-list] Re: Meteorite-list Digest, Vol 26, Issue 30
From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Mon Feb 13 17:38:44 2006
That's a wonderful piece of data (and I can't
dare say "it's hard to swallow...").
Darwin had first described the Australites
in his account of the voyage of the Beagle in
1844, with a very nice illustration of a classic
flanged button. Darwin assumed they were
volcanic obsidian but couldn't explain the
Temporarily lost the reference, but shortly
thereafter, this geologist wrote that the "wrinkles
and ridges" of tektites were emu gizzard wear.
So he was right about the emus but wrong about
the origin of the surface features...
I've seen lots of dead critters on Illinois
backroads, but never a dead emu, so no
chance of picking up a nice australite that way...
Sterling K. Webb
----- Original Message -----
From: "Norm Lehrman" <nlehrman_at_nvbell.net>
To: "Sterling K. Webb" <sterling_k_webb_at_sbcglobal.net>; "Steve Schoner"
Sent: Monday, February 13, 2006 8:57 AM
Subject: Re: [meteorite-list] Re: Meteorite-list Digest, Vol 26, Issue 30
> I too got drawn into tektites by the mystery. They
> often tell their individual stories plainly, but we
> still can't get the big picture out of them!
> One comment on your comments though. Tektites
> (australites) ARE very often emu gizzard stones. In
> the dry lakes where they are most abundant there are
> typically only two rock types surviving. Sharply
> angular little bits of quartz shattered by halite
> growth and the relatively smooth and conspicuous
> little australites. The latter are selectively picked
> by the emus. The aboriginees always check the
> gizzards of emus taken hunting for australites---and I
> always checked emus killed on the roadways! That
> theory is not a theory.
> Best regards,
> --- "Sterling K. Webb" <sterling_k_webb_at_sbcglobal.net>
>> Steve, List,
>> It's why I love tektites, as a puzzle.
>> Every theory explains some features;
>> no theory explains all the features of
>> those little devils.
>> I regard them as still a wide open
>> mystery, the only scientific mystery
>> still going strong after more than 200
>> years of hypothesis. (The first tektite
>> theory was published in 1788, long
>> before the first scientific theory of
>> meteorites, which had not even been
>> accepted as real yet.)
>> I keep a table of all the theories of
>> tektites, ancient and modern, and I have
>> 39 listed, including the one that assays
>> that they are the gizzard stones of emus!
>> There are several lunar theories. Nininger
>> (at one time) believed them to be Lunaites, or
>> ejecta from lunar meteoroid impact. Chapman
>> suggested that they were the material that
>> makes up the bright "rays" that a few young
>> lunar craters display, ejected all the way to the
>> Earth, thinking this would account for their
>> terrestrial distribution pattern (it doesn't).
>> Lunar vulcanism of the ordinary
>> volcanic variety has been suggested
>> several times, the last time by John
>> O'Keefe, who refined it to a suggestion of
>> deep hydrogen volcanoes with hypersonic
>> hot gas plumes, before moving on to another
>> I am not, BTW, denigrating O'Keefe
>> for changing theories in mid-stream. O'Keefe
>> put forward FIVE theories by my count, which
>> gives him more theories than any one else on
>> my list. He spent his not inconsiderable talents
>> on the problem, but all the theory buckets have
>> holes in them and leak like crazy, not just his,
>> but all of them.
>> Today, we have the impact "consensus"
>> theory, which is actually not a consensus at
>> all, because every impact theorist of note
>> has a tektite impact origin theory of his own
>> which is not compatible with any other
>> impact theorist's tektite theory!
>> But it's called a consensus because the
>> real consensus is that there is no point in
>> wasting any more time on tektites. We've
>> done them to death, performed every test;
>> it's time to move on and just accept the least
>> whacky answer by (unspoken) default.
>> Don't get me started; I wrote that post
>> chewing over the impact theories a long
>> time ago... I even have a pet theory of
>> my own (I call him Bruno and feed him
>> regularly) that manages to explain a lot of
>> tektite puzzles that the other 39 theories
>> don't, but --- guess what? My pet theory
>> has different but glaringly obvious flaws
>> all its own, so it's DOA, just like all the
>> other tektite theories.
>> They're a paradox. They're a problem.
>> They're like the jigsaw that seems to going
>> so well until somebody holds up a piece
>> you'd forgotten about and innocently says,
>> "Where's this go?"
>> Sterling K. Webb
>> ----- Original Message -----
>> From: "Steve Schoner" <schoner_at_mybluelight.com>
>> To: <meteorite-list_at_meteoritecentral.com>
>> Sent: Sunday, February 12, 2006 2:41 PM
>> Subject: [meteorite-list] Re: Meteorite-list Digest,
>> Vol 26, Issue 30
>> As Sterling Webb wrote, if the reasoning he posited
>> follows then there is no
>> way that tectites came from the moon. The
>> distribution on the earth, the
>> ablation shapes, stretch forms, and lack of cosmic
>> ray exposure pretty much
>> eliminate the moon as the source.
>> Steve Schoner
>> IMCA #4470
>> Date: Sun, 12 Feb 2006 03:00:46 -0600
>> From: "Sterling K. Webb"
>> Subject: Re: [meteorite-list] Orbital debris
>> watching radar
>> To: <cynapse_at_charter.net>, "Meteorite List"
>> Content-Type: text/plain; format=flowed;
>> Hi, Darren,
>> I gather from the phrase about having their
>> orbits decay,
>> that by "Earth orbit," you mean "in orbit about the
>> Orbits around the Earth only "decay" because the
>> touches the uppermost atmosphere enough to cause
>> which, however minute, reduces orbital velocity. It
>> may seem
>> logical that materials kicked off the Moon would
>> easily and
>> immediately end up in an orbit around the Earth, or
>> at least
>> some of them would.
>> But the truth is that it is nearly impossible to
>> get from the
>> Moon to the Earth, and that lunar meteorites almost
>> do not arrive at the Earth that way, however
>> illogical that sounds.
>> The many simulations of transfer of materials
>> around the
>> solar system show the same result: impact materials
>> from the
>> Moon mostly go into eccentric solar orbits. a small
>> go into "co-orbits," that is, they enter solar
>> orbits very similar
>> to the Earth's orbit, sort of wandering along with
>> us, and it is
>> from that population that some get tangled up with
>> the Earth's
>> gravity and get pulled in. "Short" transit times are
>> 10,000 years.
>> When a lunar shows no cosmic ray exposure, that only
>> that it was less than 25,000 years.
>> The reason why it's so hard to get from the Moon
>> to the Earth
>> is this: any object that falls to the Earth from a
>> "great distance"
>> achieves escape velocity by the time it gets very
>> near to the
>> Earth. And escape velocity is just that: you
>> escape. No orbiting
>> for you...
>> There is a point, between the Earth and the Moon
>> where the
>> gravitational pull of the Earth and the Moon balance
>> each other.
>> Since the Earth is heavier than the Moon that point
>> is closer
>> to the Moon than the Earth. The point that lies in a
>> straight line
>> between the Moon and the Earth is the first LaGrange
>> But there are a multitude of points in every
>> direction where
>> equal force vectors from the Moon and the Earth
>> meet: a sheet
>> of zero gravitational potential.
>> If an object is ejected from the Moon's surface
>> toward the
>> Earth without enough velocity to reach the zero
>> sheet, it falls
>> back toward the Moon.
>> If it arrives at the zero sheet with just a
>> smidge of velocity
>> more than zero, it will fall toward the Earth,
>> ramping up to
>> escape velocity or near escape velocity at its
>> closest approach
>> then roar on out into the solar system.
>> If it arrives at the zero sheet with a good deal
>> of velocity
>> more, it will fall on an Earth-influenced path and
>> ramp up to a lot more than escape velocity...
>> So, you see, stranger, thar ain't no way to get
>> thar from here...
>> Sterling K. Webb
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Received on Mon 13 Feb 2006 05:38:29 PM PST