Most people know that Earth’s magnetic poles are not located in the same place as its geographic poles. The magnetic poles represent the two locations where Earth’s magnetic field point vertically downward. Currently, what we think of as the North Pole is actually a magnetic south pole, and vice versa. I say “currently” because the magnetic poles can completely swap locations and have many times throughout the planet’s history. The geographic poles represent our approximation of the Earth’s rotational spin axis. Both types of poles move relative to the Earth’s surface. The spin axis (geographic pole) moves on the order of centimeters per year – this type of shift is called “true polar wander.” The magnetic poles move kilometers per year. As such, we don’t worry much about having the geographic pole fixed on our coordinate system (at +90 and -90 degrees latitude).

What people may not know is that the dipole model of our magnetic field is far from perfect. The magnetic poles are not located at antipodes (opposite points on the globe). They move at different rates and in different directions every year. I’ve presented that here with a map and graph. The map shows how the locations have varied as a function of time, while the graph emphasizes the differences in movement rates.

The take-home lesson is: when you are in Antarctica, don’t try to use a compass.

Data source: http://www.ngdc.noaa.gov/geomag/data.shtml