N:dlzc D:aol T:com (dlzc) wrote:
Dear Yousuf Khan:

"Yousuf Khan" wrote in message
...
Sometimes you wish people would just get their
stories straight sometime. According to this theory,
Mars' magnetic field got shut down by a supergiant
asteroid hitting it, probably about the size of Texas.

Hit a magnet with a hammer, and you risk demagnetizing it.

That'll work with a permanent magnet, but not an electromagnet. I'd say
a planet is closer to an electromagnet than a permanent magnet.

So why didn't something like that shut down
Earth's magnetic field?

Liquid, differentially rotating, core.

Which apparently both Mars and Venus had at one point too, just like the
Earth.

Well, because you'd need an even bigger asteroid
to affect the Earth. Well, isn't the leading theory
of how the Moon formed, that a planetesimal the
size of Mars itself hit the Earth? Wouldn't that be even bigger
than a Texas sized asteroid? No answer.

Use your head.

Elaborate.

Then the most ludicrous one is the explanation
about Venus. So why doesn't Venus have a
magnetic field? Well its mantle is too dry and stiff to allow
for a dynamo effect! So why is Venus's
mantle so stiff and dry? Is it because Venus's water
disappeared, that's why it's so dry in its mantle? If it
had a magnetic field it wouldn't have lost its water,
and if it had water, it would've had a magnetic field.

We still haven't gotten off this planet. Enjoy the conundra
while you can. Obviously, Venus does not have Earth's history.

Even after we get off this planet, we still would have a ways to go
before we can go back in history.

Yousuf Khan