A magnetic compass The Earth has its own magnetism—an invisible field of magnetic force all around us. Too weak to notice in daily life, the magnetic field affects iron-based materials and other magnets. We can detect it using a magnetic compass. The compass needle is a long, thin magnet that lines itself up with Earth’s magnetism to point north-south. This helps us to read maps and find our way in remote places.
The lines of magnetic force in the Earth's magnetic field run between north and south poles as if there were a bar magnet inside the Earth, tilted at an angle of 11° from its axis of rotation. The North Magnetic Pole is the point on the surface at which the Earth's magnetic field points vertically downwards into the Earth. The Earth's magnetic field changes over time, and both the North Magnetic Pole and the South Magnetic Pole wander around from one year to the next. Luckily, these movements are too slow to affect a compass's usefulness in navigation.
Map showing the location of Geographic, Magnetic and Geomagnetic North Poles in 2016
At certain intervals, on average several hundred thousand years at a time, the Earth's field reverses completely: the north and south magnetic poles swap positions.
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