From: Doug Jones (djones@xcor.com)
Date: Wed Jun 27 2001 - 12:07:34 MDT
Mike Lorrey wrote:
> Actually, not. You are forgetting repetition. How many times did the
> object fly by the earth and moon? We don't know. The evidence stated
> earlier indicates the possibility of a 4 million year period. If the
> object was a Near Earth Asteroid, that gives the possibility of an
> average of 4 million near misses to perturb the moon's orbit.
Mike, this is handwaving. It's an interesting idea, but you need to put
some rigor into your logic.
A) Close approaches tend to scatter the small object into an escape
path, or into impact or encounter with Jupiter. A comet or asteroid in
the inner solar system would have (over the course of a million orbits
or so) only a handful of close approaches. Close, in this context, is
less than a million kilometers from earth- and any object coming close
enough to the moon the perturb it, would be far more strongly scattered
by the earth. It won't get multiple chances at the moon.
B) Repetition would cause random fluctuations, not a cumulative change.
> To create volcanic/tectonic problems, all that is required is for the
> moon's orbit to change faster than the earth's tectonics can adjust.
Nope. Earth's tectonics adjust to tides twice a day. The rate of
change of tidal stresses in the bulk of the earth is measured in
reciprocal hours; the rate of change of the moon's orbit is reciprocal
eons.
> Sustained vulcanism in terrestrial bodies after the primordial period of
> cooling in our solar system can be shown to be exclusively caused by
> tidal forces:
*Some* terrestrial bodies. Earth is two orders of magnitude larger than
the Jovian moons, and it has more primordial and radioactive internal
heat. The tidal stress and heating of the jovian moons is several
orders of magnitude greater than that of earth, so while they *are*
tidally heated, earth is not significantly.
> Venus's volcanos : caused by solar tides (which are 4 times greater than
> the sun's influence on earth, which is significant enough to cause the
> moon to crab out of its tidally locked rotational rate) and Venus' slow
> retrograde 240 earth day long day.
The slower Venus rotation actually makes tidal heating of Venus far less
than that of earth, because the power is a function of the rate of
_change_ of the tidal stress. Flexing a paperclip once every 240
seconds will heat it a lot less than bending it 1/4 as far once every
second.
> Earth's volcanos : caused by the moon
I don't want to go chasing down the numbers right now, but I'm very,
very certain that the vast majority of earth's internal heating is not
tidal. Tell ya what- you're the one making the extraordinary claims,
how about you dig up the extraordinary evidence?
> Io's volcanos : caused by jupiter
True enough- but the tides exerted on Io are 1000 to 10000 times greater
than those on the earth, so even with their limited angular rate, the
power is very high.
> Ice volcanos on icy moons: caused by the tidal influence of Jupiter or
> Saturn (whichever they orbit).
>
> Note that Mars, which has no source of tidal influence, has a cooled
> core and is now volcanically dead. The earth's moon, which a) has no
> significant heavy metal content, b) is made up almost exclusively of
> crustal material blasted off of primordial earth by a planetesimal, and
> c) is of too small a diameter for earth to exert significant enough
> tortional forces to cause a differential in rotational velocity between
> its geological layers (as occurs between our core and mantle layers),
> and d) does not rotate with respect to the earth, so any tortional
> forces exerted by earth's tidal influence do not do any actual work.
a) is most of the reason for earth's heat, b) is a restatement of a), c)
means it is tidelocked aside from minor libration- but the internal
differential rotation of the earth is, from the theories I've seen,
caused by convection not tides, d) explains why venus has little tidal
heating.
> Additionally, as I said, the Yucatan impactor could merely have been a
> calved fragment of a larger body that broke up either from impact with
> the moon, or from the moon and earths gravity exerting too much repeated
> stress upon its structure.
An object impacting the moon would be pulverized, not calved- supersonic
impacts work that way. Objects broken up by passing through the roche
limit of a planet turn into long streams of impactors, much like
Shoemaker-Levy 9. Mike, you should clarify your understanding of the
many fields your theory encompasses, test it for consistency, find
supporting evidence, and do accurate numerical calculations of the
likely magnitudes the effects induced. I think you'll find that your
chain of logic does not hold up.
-- Doug Jones, Rocket Plumber
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