> In a message dated 6/21/98 12:52:54 PM Central Daylight Time,
> retroman@together.net writes:
>
> > It could have a moon
> > only a few hundred miles across to give it sufficient tide to enable enough
> > tectonic activity for volcanic fertilization, for maintainance of the
> mantle/
> > core
> > dynamo that would generate a radiation protection EM field,
>
> Interesting.
>
> I'd be interested to know more about this. Why is it that earth has tectonic
> plates..a molten core...etc....but venus, our moon... and and presumably the
> other rocky planets do not...? I was under the impression that it had to do
> with radioactives in the core...releasing heat and keeping it molten. But if
> that was the case then venus should be similar.
>
> First I ever heard of the moon's influence keeping the core molten...assuming
> I understand this correctly.
While there is some heating from radioactive decay, such decay should over time
decrease on a half life basis, yet the rate of thermal conduction from within the
earth has remained rather steady, or declining at a very low rate. Since we now
know that the earth's EM field, which protects us from cosmic and solar radiation,
is generated by a dynamo mechanism within the earth that is created by the tidal
influence of the moon, and we can measure this influence, we can also measure the
amount of heat generated by the moons tide creating friciton, and thus heat,
within the earth. For example, we now know that the mantle and outer lithosphere
rotate one more day per year than the core does, and it is this slippage between
the layers that makes the earth behave like a big electric generator, with the
core being the rotor, and the mantle being the stator.
Technotranscendance (Daniel Ust) said:
> My own understanding of this is that Venus does not have plate tectonics
> because it does not have a well defined crust. A lot is still unknown about
> Venus, but it appears the surface is too hot for a brittle crust like Earth's.
>
The high temperature and pressure of the atmosphere does cause the crust
materials to be much stronger than they would be at earth normal pressure and
temp, which is why mountains have been found to be so steep on Venus, much more so
than rock on earth could withstand, however Venus also has a thicker lithosphere
than the earth does, which could explain why it doesn't have such plate tectonics.
Why does it have such thick crust? Probably because it hasn't had the moon to keep
it well stirred for billions of years.
>
> I've never heard of the idea of tidal forces having much to do with plate
> tectonics since seafloor spreading was discovered in the early 1960s (or
> so?). Wegener's original theory of continental drift posited tidal forces as
> the cause of drift. Modern (post-1960) theories of plate tectonics -- e.g.,
> plate mosaic theory, which appears to be the current conventional wisdom
> -- posit convection in the mantle as the proximate cause of plate movement.
Plate tectonic movements over time are, prima, caused by the upwelling convection
currents of magma within the upper mantle spreading them apart. However, since all
continents were at one time a single supercontinent, which significantly perturbed
the center of gravity of the earth, it would take much greater forces than simple
upwellings to break them apart. Keep in mind that there are plenty of volcanos,
like Hawaii, as well as the large single volcano detected on Venus, which are
caused by magma upwelling convections which are not at spreading zones.
The most likely original cause of the breakup of Pangea was a conflict between the
earth's center of gravity, the earth's center of rotation, and the center of
angular momentum in the earth/moon system. As it is, the center of angular
momentum is at least a couple kilometers off center from the current center of the
earth, and it is this asymmetry which maintains the core/mantle dynamo that
generates the earth's EM field.
>
>
> The Earth's moon appears to not have plates because it does not possess
> a the same kind of highly convective mantle as Earth. Ditto for Mars.
Granted a planet with a cooler mantle would not have the elasticity required to
support either theory, however, we can see that Jupiter's moon Io has extensive
volcanos, indicating upwelling is present, and is under one of the highest levels
of tidal influence in the solar system. While Mars, with no significant moons has
a few large extremely dead volcanos, and Venus has one large volcano, the two most
volcanically active planets/planetoids in the solar system share two significant
traits: they are both under a significant amount of tidal stress, and they both
have heavy metallic cores.
Convection is a side effect of tidal stresses.
-- TANSTAAFL!!! Michael Lorrey ------------------------------------------------------------ mailto:retroman@together.net Inventor of the Lorrey Drive MikeySoft: Graphic Design/Animation/Publishing/Engineering ------------------------------------------------------------ How many fnords did you see before breakfast today?