A very overdue Friday Fact: Magnetohydrodynamics, or why the North Pole is getting away from us

I was talking to my brother the other day, and somehow we got to talking about an issue that would very much affect people in his field of study, computer science.  Evidently, some of his colleagues in the department are crying doomsday about Earth’s magnetic field doing a full somersault in 2012 so that North is South and vice versa.  And they should be concerned, because if this were the case, it would throw off most things electronic. 

But being my normally contradictory self, I told my brother, “That can’t be right,” and thus turned to my most reliable research tool: Google.  I found out that, as usual, I’m right. 

But as much as I hate to admit it, my brother’s a little bit right himself. 

What his misinformed colleagues had heard about was the sun’s magnetic reversal.  The sun indeed has a magnetic field flip roughly every eleven years, and it’s due to flip in 2012.  So no fear, the end is not near. 

It turns out, though, that the Earth’s magnetic field can also do a complete flip.  We’ve known for a long time that the magnetic pole (which isn’t synonymous with the geographical poles) moves a lot.  At the beginning of the century, it was moving about 10 km a year, and sped up to 40 km a year by the end of the century.  According to the NASA website, it’ll end up in Siberia in a few decades. 

The thing that’s got some people worried is the fact that field has weakened 10% since the 19th century.  A weakening could signal a field flip.  And since the last one was 780,000 years ago, some think we’re overdue.  Hence the cry of a collapsing magnetic field. 

But researchers say this isn’t so.  People who study Earth’s past magnetic field, paleomagnetists, explain that a weakening doesn’t necessarily signal a reversal.  The field has weakened in the past, and poles have shifted, and then reversed direction and headed back.  Besides, reversals take a few thousand years, and during that time, the field doesn’t disappear.  It just becomes tangled, with multiple magnetic poles. 

All of this is governed by something called magnetohydrodynamics.  In the middle of the earth, there is a solid iron core covered by metallic ocean.  This core rotates faster than the earth itself, and its surface has currents and even the equivalent of hurricanes that cause changes in Earth’s magnetic field. 

This is both fascinating and good news!  If you were worried about the magnetic poles, remember that you shouldn’t flip out until they flip out. 

For more information, look NASA’s explanation: http://www.nasa.gov/vision/earth/lookingatearth/29dec_magneticfield.html.