The dynamics of planetary magnetic fields are not well understood, but the
most widely accepted theories rely on some sort of dynamo effect, which
requires a liquid iron core. This isn't just a factor in the reversal of the
magnetic field, but in the existence of a significant field at all. Other
planets that no longer have liquid cores (Mars and Mercury) have very weak
magnetic fields as well. Evidence suggests that Mars once has a much
stronger field, on the order of 10% the strength of Earth's. Venus is a big
unknown: it has a very small magnetic field, but there is almost nothing to
indicate the state of its core.
It seems likely that when the Earth's interior cools sufficiently that we
loose the liquid iron core, we will also lose most of our magnetic field
(and therefore the protection it affords us). Not that there are likely to
be any humans around by then!
Chris
*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com
----- Original Message -----
From: "Pete Shugar" <pshu...@clearwire.net>
To: "Jeff Kuyken" <i...@meteorites.com.au>; "Rob McCafferty"
<rob_mccaffe...@yahoo.com>; <meteorite-list@meteoritecentral.com>
Sent: Saturday, September 05, 2009 9:48 PM
Subject: Re: [meteorite-list] Slow cooling rate of irons in space
I'm not sure 100%, but the liquid state of the iron core with its
corresponding movement is what's responsible for the shifting magnetic north
and south poles of the earth.
Were it to cool to a stable mass (read non molten) I believe
the Earth's magnetic poles would no longer shift.
Just my thoughts on the matter.
My area of expertise is in Electronics, not geophysical sciences.
Pete
----- Original Message -----
From: "Jeff Kuyken" <i...@meteorites.com.au>
To: "Rob McCafferty" <rob_mccaffe...@yahoo.com>;
<meteorite-list@meteoritecentral.com>
Sent: Saturday, September 05, 2009 9:10 PM
Subject: Re: [meteorite-list] Slow cooling rate of irons in space
This is one of the best threads I've seen on the list for quite a while.
Interesting stuff!
So have the Martian Rovers found specific evidence from any changes that may
have taken place on Mars when it cooled? And what happens when the Earth
cools? Will this affect things like the Earth's electromagnetic field?
Cheers,
Jeff
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