Re: Searching for Theia, the mother of the Moon

On Apr 18, 7:30 pm, "N:dlzc D:aol T:com \(dlzc\)" <dl...@xxxxxxx>
wrote:
Dear Yousuf Khan:

"Yousuf Khan" <bbb...@xxxxxxxxx> wrote in message
N:dlzc D:aol T:com (dlzc) wrote:
I didn't get the reference to "remains of 'Mu'".

I guess I read too much speculative fiction as a youth.  The
proposal was that there was a giant continent Mu, to offset the
supercontinent Kenorland (or whatever our current configuration
sprang from).  Mu spawned into the Moon.

Oh, I see, they assumed that the spin of the Earth would be affected
if all of the continents piled up on one side of the globe. It seems
that whenever we have had the previous supercontinents (like
Kenorland, Vaalbara, Rodinia, Pangaea, Columbia, Laurasia & Gondwana),
it created a global cooling event which led to drought and reduced sea
levels: possibly a lot of water locked up in ice. Reduced water levels
probably led to reduced spin perturbations.

Some people say that we likely have a supercontinent on our planet
right now too. If you look at the globe, we have Asia touching North
America through the shallow seas of the Bering Straits. We have North
America touching South America, of course. We have North America
touching Europe through the shallow seas going through Greenland and
Iceland and the Arctic Ocean. Europe of course touchs Asia. Asia
touchs Africa. Africa also touchs Europe through the shallow seas of
the Mediterranean. Asia touchs Australia through the shallow seas
surrounding Indonesia. The only continent not part of this horde is
Antarctica. Maybe there is a residual shallow sea between Antarctica
and South America? We'll have to wait for Google Ocean to map it for
us.

But by comparison Venus should be big enough to
have kept all of that, yet it didn't.

Are you sure?

No, I'm not sure, but the opposite question is just as puzzling: if
Venus wasn't big enough for any of these things, then why was the
Earth?

Venus should have been able to held on to its water, but it
didn't.

Sulfuric acid *is* a lot of water.  Given much in the way of
elemental sulfur, most of our water would be tied up in sulfuric
acid too.  I just think you are counting Venus out a bit too
fast.

It should have a magnetic field, but it doesn't. Now, we
find it's got barely any continentalization on its surface.

Acid rain could do that bit too.

Is acid more erosive to rocks over several billions of years, than 3
km of water and 118 km of air is on Earth? My assumption is that the
rocks on Venus that are affected by acid have already corroded away,
and what we have left is that which isn't affected by acid.

If Venus were a water world like Earth, then more than
90% of it would be under water, since it's got such tiny
continents. But of course we know it couldn't hang on
to its water either. It's a mystery why such nearly
identical twin planets turned out so fraternal.

Different histories do that, I guess.

If you look at the known history of the Earth's plates,
you see that by and large, the continents have
remained the same throughout its history compared
to the seas. Yes, the continents rearrange themselves,
crash into each other, raise mountains, form
supercontinents, and break apart again, etc. But it
seems to be nearly the same plates have continued to exist
since their initial formation. By comparison, the
oceanic plates are the ones that get ridden over by
these continental plates. When two plates crash into
each other, it is the oceanic plate that ends up being
subducted under the continental plate, not vice-versa.

For which life on Earth can be thankful...

Well, land life anyways. Sea life would've existed either way.

I think the difference between the two is the "dynamo" at the
core of the Earth.  It provides the crustal flow and the magnetic
field.

There must be something powering the Earth's dynamo. Large uranium
deposits inside the Earth's iron core keeping it hot and spinning. The
question is why Venus didn't have a similar power source?

Well, we did say that the Moon is mainly the lighter
materials, such as silicates. The heavier materials like
iron, sank to the bottom of the core.

It is 60% the density of the Earth.  I doubt it got much iron
from Earth.  The Moon and Mars are awfully close in density... as
are a number of asteroids.

Maybe that's as dense as terrestrial planets get, if they don't have a
big iron core in their centers? The Moon and Mars don't have a big
iron core, but the Earth does. What's Venus's density? I bet it's
pretty close to Earth's too. Mercury is apparently the most dense
planet in the solar system, because it's nearly entirely iron.


Insulation between the Earth and the Sun lowers our
temperature. And there was a post recently that the
Earth is passing through such a dust cloud, if not as
thick as it would need to be.

Oh, I see what you mean. But that dust cloud would
have to be immense to provide such level of insulation
that it blanketed the planets out to the heliosphere.

I found a link:http://news.uchicago.edu/news.php?asset_id=1537

Was it always as sparse as it is now?  2300 ly seems a long way
to send dust.

Okay, but what has it got to do with dust around our own solar system?
They don't mention any link to our solar system.

Yousuf Khan
.

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