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The Difference Between Geographic North & Magnetic North

North is found in varying location depending on if you are looking at a map or if you are reading a compass. Depending on your location, this is either a small difference or a large difference. The reason for this is that a compass doesn't even point to the North Pole or even the South Pole for that matter. Furthermore, when the compass points north it will point to one location this year, but next year it will point at a new location. This means while the geographic North Pole is constant, a compass won't get you there if you follow it directly without changing some settings.

Geographic North Pole
- Geographic North Pole (also called Terrestrial North Pole) is the axis on which the earth spins. If you were to take a rod and jam it into the earth at the very top of the planet and run it all the way through then out the bottom, this would represent the Earth's axis. The top would be the Geographic North Pole where the axis of rotation meets the Earth's surface. Geographic North Pole is actually in the middle of the Arctic Ocean -- covered with shifting ice -- with Greenland as the closest landmass.
Magnetic North Pole
- The Magnetic North Pole, on the other hand, is constantly moving. It is the point in which the Earth's magnetic field points down vertically. The Magnetic North and South Poles are actually the ends of the magnetic field around the earth. In the Earth's outer core, there are magnetic elements floating around in molten rock, responsible for producing the Earth's magnetic field. This molten rock does not align with the Earth's axis in unison; therefore, Magnetic North Pole does not align with Geographic North Pole.
Magnetic Declination
- The difference between Magnetic North Pole and Geographic North Pole is called magnetic declination. Depending on where you are on Earth, the declination is either small or very large. For example, if you were in the United States on the Mississippi River in 2001, Magnetic North Pole and Geographic North Pole were in alignment resulting in 0 degrees declination. As you move east or west, the declination changes to either West Declination as you moved east, or East Declination if you moved west. Furthermore, since Magnetic North Pole is always shifting, declination changes every year. You should always review the most updated declination map for accuracy of magnetic declination as even the rate of change is not constant.
Adjusting Your Compass
- Once you have an updated declination map, you will need to adjust your compass to your current location. Most compasses have a declination screw at the top of the compass. If your compass does not, it would be wise to purchase a new compass, unless you constantly want to do that math in your head during on your trip.. If your updated map says your location's declination is 20 degrees west, simply turn the declination screw to 20 degrees west. If your compass doesn't have a declination screw, add 20 degrees to the reading on your compass.

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