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I read that the north and south poles switch postions after several hundered thousand years. Why is this?

Hi,

It sounds like you are asking about the Earth, but since this is solar week, I thought the questions are about the Sun.

So if you are asking about the Sun, and about the solar magnetic field, the polar fields reverse about every 11 years on average, not as long as the Earth's magnetic polarity. If you are asking about the Earth, it is not my research area.

The solar polar reversal is not fully understood. It is related to the solar rotation and solar magnetic field migration. Some apparent features observed on the solar surface (the photosphere) show that the magnetic field move poleward after the sunspots (carries strong magnetic fields) emerge at lower latitudes and interact with the polar fields. After about 11 years, the current polar fields get replaced by a different polarity. But some studies show that only the surface magnetic feaures and motions are not enough to cause the polar reversal. Scientists are still working on it.

Hope you think this is interesting anyway, which I definitely do!

Yan Li

I don't know much about the Earth (terrestrial) poles switching either, except that I know it has been moving quite rapidly recently (recently meaning within the last 100 years or so).  For some more information, take a look at http://www.newscientist.com/article.ns?id=dn4865
and
http://curious.astro.cornell.edu/question.php?number=523