Too Big For Your Pocket, But a Magnet Nonetheless

The Earth's magnetic field is shaped somewhat like that of a bar magnet. It has two magnetic poles, one in the Canadian Arctic (called the North Magnetic Pole), and one off the coast of Antarctica (called the South Magnetic Pole).

At the North Magnetic Pole (NMP) the Earth's magnetic field is directed vertically downward to the Earth's surface. Magnetic "dip", or inclination, is 90°, and that will be your eventual destination if you follow the direction of your compass needle from anywhere on Earth.

A dip circle is used to measure the vertical or "dip" angle of the Earth’s magnetic field - much the same way as a compass measures the horizontal angle. The one in the picture (right) belonged to the lost Franklin Expedition.

Now for the goofy part - the end of a bar magnet at which the magnetic field is directed outward is termed the "north" pole, and the end at which the magnetic field is directed inward is termed the "south" pole.

The Earth's magnetic field is directed downward in the northern hemisphere and upward in the southern hemisphere. This implies that the "north" magnetic pole in the Arctic is really a "south" pole - and the "south" magnetic pole in Antarctica is really a "north" pole.

However, by long custom and because people had already named the geographic poles before they figured out all that "magnetism" stuff, the magnetic poles are named to match their geographical neighbours (nobody wanted to change all of those maps).

Anyway, it's believed that the poles can move so much that they can actually change. In another 100,000 years or so, the magnetic poles could flip.

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