"Joseph Lazio" <jlazio@adams.patriot.net> wrote in message
news:llsmp09lk7.fsf@adams.patriot.net...

"DT" == Dennis Taylor <noemail@nospam.org> writes:

Well, no.  A huge difference between Earth and Venus, in addition to
the presence of a moon, is the thickness of their atmospheres.  I've
certainly never heard of the Moon's tides as being responsible for
keeping the Earth's interior molten.  That is ascribed to the presence
of radionuclides in its interior.  Venus is different, not only
because it has lost its oceans, but because its atmosphere keeps the
surface so hot.

Well, there's a slight but significant difference between a molten core and
plate tectonics. I don't think anyone's actually ever claimed that Venus is
solid to the core, just that it has no plate movement. And given that the
moon *does* demonstratably cause a significant amount of "flex" in the
Earth's crust due to tides, I don't think it's unreasonable that A) the
energy transfer would contribute to the internal heat, and B) it would help
to keep the plates distinct. Kind of like stirring a pond that's trying to
freeze over.

As to the atmosphere, this *could* be a case of mixing cause and effect. It
may be that the atmosphere wouldn't be as thick with a large satellite to
strip it off. It may also be, as suggested in a book called "Oxygen - The
molecule that made the world" by Nick Lane, that the presence of life on
Earth prevented a Venus-like atmosphere from developing here (this sounds
like a bit of a chicken-and-egg argument, but I'm not really qualified to
rebut).