Expert: Dr Thomas Bell - 11/6/2009

Question
At one time or other, the north and south poles were in different positions (one at the Bermuda triangle and one at the devils triangle near japan. What would have been the affect of a pole shift on the planet and can we predict when its going to happen again.
allan

Answer
Allan,

Earth's geographic poles have remained more or less in the same place for the last 4 billion years.  Like a child's top, there is a little wobble but the points on Earth that mark its rotational axis are pretty stable.  North has always been north and south has always been south.

The magnetic poles are an entirely different manner.  These geographic points mark the axis of Earth's magnetic field.  The magnetic field increases and decreases in intensity and even dies out entirely every few tens or hundreds of thousand years.  The magnetic poles wander around a bit but are more or less aligned with the axis of Earth's rotation because they are generated by the rotation of Earth's iron outer core.  Every now and then, the polarity of the magnetic field does a flip flop.  It would be like reversing the wires on the transformer that used to run your electric train when you where a kid.  When you switch the positive wire for the negative wire, the train ran backward.

As a matter of fact, evidence has been growing that Earth's magnetic field is in the process of collapse and perhaps one of those once in 50,000 year magnetic reversals.  If that happens, you can throw that old Boy Scout compass away because the north end of the needle will then point south.

To learn more about Earth's magnetic field check out these web sites:   

http://science.nasa.gov/headlines/y2008/16dec_giantbreach.htm
http://www.pbs.org/wgbh/nova/magnetic/about.html
http://news.nationalgeographic.com/news/2004/09/0909_040909_earthmagfield.html
http://www.agu.org/sci_soc/cowley.html