[meteorite-list] Planet V (for Five)

From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Fri Apr 28 12:07:52 2006
Message-ID: <008a01c66a5d$ab0d82d0$e420e146_at_ATARIENGINE>

Hi, Darren, List,

    Yeah, an unfortunate name choice! When I
Googled Chambers and his notion, I found lots
of disparaging references to its being a kind of
V-for-Velikovsky idea. Also, humorous accusations
that he was resurrecting the Titus-Bode Law, or
reviving the Lost Planet from which the Asteroid
Belt formed. He needs a better name, but nothing
comes to mind. The Rogue Planet? Planets Gone
Wild? The Drunk Driver World?
    He's not doing any of those things, of course.
He puts his Planet V at 1.9 AU instead of the
Titus-Bode distance of 2.8 AU. He assumes
the Asteroid Belt is in place, and that when
Planet V's orbit becomes more eccentric, it
starts throwing stuff into the inner system,
hence the Late Bombardment.
    The Venus thing was my idea, not his. But
we can't just ignore the possibility of encounters
and collisions just because Velikovsky picked
it to pin his whacky notions on. Venus requires
an explanation (just not Velikovsky's, please).
    At the time when the solar nebula of gas and
dust was being cleared out and only planetesimals
remained to be accreted into planets, there were
LOTS of big ones. There were many Planet
V-sized objects around.
    Just to assemble the mass of the Earth requires:
                    5 Marses
                    3 Moons
                    12 Iapetuses
                    and so on, down to
                    100,000 1-kilometer bodies
    50% to 70% of the Earth's mass comes from the
larger bodies on the list. Accretion always starts with
tiny grains and builds up to larger and larger bodies.
    Without impacts, all the planets would be standing
up straight on the ecliptic plane without any tilts to
their axes. Since there are tilts of the axis in all the
planets, we're pretty sure there were impacts. If there
were ONLY little impacts, they would cancel each
other out and there would be no tilts, so we're
pretty sure there were lots of BIG impacts.
    Even Jupiter has a three-degree tilt. Ya know
its gonna take a good whack upside the planet to
tilt Jupiter! Uranus is tilted over on its side; it
takes an impact with an Earth mass object to
deliver that amount of change in momentum.
Turning Venus's axis upside-down and almost
stopping its rotation requires the energy of
a Mars-sized object.
    The real problem is that folks like things settled
and fixed. OK, the early Solar System was violent
chaos, but things quieted down 4.5 billion years ago,
and we want to think they stayed that way forever.
But it can't have been that way.
    Time to drag in meteorites! Irons are actually
more varied than stones, but the differences are
not visible, being in their isotopic composition. There
are 80+ types and they come from a minimum of
60 parent bodies and probably more.
    They all have isotopic formation dates back to
the beginning of the Solar System (4.5xxx billion
years) but widely differing crystallization ages. The
longer they took to cool and set, the bigger the
parent body they were the core of. One small
group has a crystallization age of 3.7 billion years
and another 3.43 billion years. This means that
they were in a really big parent body. Since they're
out floating around loose now, that large body
was completely disrupted AFTER those dates.
More big impacts required.
    Cosmic Ray Exposure (CRE) dates tell us how
long chunks of core have floated around as the small
fragments we find now. If collisions are uniform and
random we would find CRE ages spread out, but
instead there are sharp peaks around which CRE
ages cluster, at 1000, 650, and 400 million years
ago. At those dates, there were big episodes of
collisions and breakups, flurries of big impacts.
    Interestingly, there are very few irons with CRE
ages in the last 100 million years, so, yeah, things
have been pretty calm lately. Nice orbital weather
we're having...
    And, you can add to the list of items that support
the Planet V-for-Five hypothesis the mesosiderites.
The Argon-40 dates of mesosiderites cluster very
nicely around 3.9 billion years (the time of the start
of the Late Bombardment). Now, the Ar40 clock is
set when an object is heated or shattered or whatever
and its existing stock of Ar40 is released and it has
to start accumulating it all over again.
    There are two explanations for this tight dating.
Mesosiderites are mixtures of iron and crustal melt
rocks (basalts) without any mantle rocks, Hmmm.
The first is kind of convoluted: a naked iron core
collided with the crust of a large differentiated body,
fracturing in the process, then re-assembling as a
mixed body which was then disrupted again to produce
the mesosiderite meteorites, all by 3.9 billion years
ago. Pretty complicated, and there's a problem with
the energy requirements to boot.
    Or... there was a really large asteroid (a minimum
of 800 kilometers, up to sub-Mars size) that was just
too hot and too slow cooling to differentiate before
it was disrupted 3.9 billion years ago. (The diffusion
of nickel in the iron in mesosiderites yields a cooling
rate of one degree every 500,000 years -- very slow.)
    Maybe it hit Planet V-for-Five. Maybe it WAS
Planet V-for-Five or a good chunk of it. Or a satellite
of Planet V-for-Five dragged along for the ride when its
orbit became unstable. Or... I look at my little chunks
of mesosiderite with new respect. I sidle up to them
at the bar and buy them a drink in the hope that they
will tell me their life story...


Sterling K. Webb
--------------------------------------------------------------
----- Original Message -----
From: "Darren Garrison" <cynapse_at_charter.net>
To: "Sterling K. Webb" <sterling_k_webb_at_sbcglobal.net>
Cc: <meteorite-list_at_meteoritecentral.com>
Sent: Thursday, April 27, 2006 9:14 AM
Subject: Re: [meteorite-list] Planet V (for Five)


On Wed, 26 Apr 2006 20:05:52 -0500, you wrote...

> And, if you're looking for other unexplained facts
>to tuck into the envelope, there's the anomalous slow,
>backward rotation of Venus (a "day" longer than its
>"year"), for which repeated close encounters with a
>large body has been suggested as a cause. Planet V?
>

Cough-Velikovsky-cough.
Received on Thu 27 Apr 2006 08:49:55 PM PDT