Compasses do not work at the poles because at these locations, the Earth's magnetic field is vertical, which disrupts the functioning of the compass that needs a horizontal field to orient itself.
In the polar regions, the magnetic field behaves somewhat differently. Up there, it becomes particularly irregular, with lots of local disturbances. The Earth has a fluid metallic core in constant motion: these internal currents create a global magnetic field, but at the two ends of the globe, the result is less regular and sometimes downright unstable. The poles are also not fixed; they shift slightly from year to year: this is referred to as the migration of the magnetic poles. These magnetic variations completely confuse the signals sent to your compass, rendering it completely lost and unusable.
Near the poles, the lines of the Earth's magnetic field bear no resemblance to those seen in the nice, horizontally aligned illustrations in textbooks. Up there, they literally plunge straight down to the ground, sinking almost vertically into the Earth. This phenomenon, called magnetic inclination, inevitably presents a problem for a magnetic needle that is supposed to pivot horizontally. A traditional compass is designed to follow relatively flat or horizontal magnetic field lines, so when these lines become nearly vertical, it's like asking a regular car to drive calmly up a wall. No wonder the needle completely loses its bearings (pun intended).
At the poles, the lines of the Earth's magnetic field plunge almost vertically toward the ground. This is quite bothersome, as a magnetic needle usually aligns horizontally, following the local magnetic field. Up there, this needle really struggles to stabilize since it tries to point downward rather than toward a clear direction of North or South. The result: the compass spins, hesitates, and becomes nearly unusable for indicating your precise direction. With an essentially vertical orientation of the magnetic field, the needle loses all its practical value. It’s like trying to follow an arrow that points straight down beneath your feet; it's hard to derive anything useful for navigation.
The surface of the Sun regularly projects significant amounts of electrically charged particles (solar wind) into space. These particles interact with the Earth's magnetosphere, a sort of magnetic shield that surrounds the planet. At the poles, the lines of the magnetic field tilt sharply toward the ground, making it easier for solar particles to enter our atmosphere. As a result, we get polar auroras, a magnificent light phenomenon that shows that in these areas, the magnetic field is disturbed and unstable. This magnetic instability completely confuses traditional compasses: the needle no longer knows where to point, the direction of north becomes total confusion.
Since the classic compass struggles at the poles, explorers use other methods. GPS has become essential: it works thanks to orbiting satellites, no matter the position on Earth. They also often use inertial navigation systems, or INS, which record every movement to accurately estimate their route. Another simple yet effective trick is visual positioning, such as relying on the position of the stars and the sun with a good old sextant. In modern expeditions, combining these tools generally allows for staying well-oriented despite the unreliable magnetic field.
At the Earth's poles, the magnetic needle of a compass tends to point downwards or upwards due to the extreme inclination of the Earth's magnetic field, making conventional compasses unusable at these extreme latitudes.
The northern and southern lights, visible respectively near the North Pole and the South Pole, are directly linked to the interaction of solar particles with the Earth's magnetic field, a magnetic phenomenon that also causes difficulties in using magnetic instruments such as compasses.
Some polar navigators use a gyrocompass instead of the traditional magnetic compass. The gyrocompass, based on the Earth's rotation, is not affected by the magnetic anomaly of the poles.
There are two distinct North Poles: the geographic North Pole, where the imaginary lines of longitude converge, and the magnetic North Pole, where the lines of the Earth's magnetic field converge. Many travelers often confuse these two poles.
The geographic North refers to the fixed point corresponding to the Earth's axis of rotation. Magnetic North, on the other hand, varies over time and corresponds to the direction that the magnetized needles of compasses naturally point towards. The difference between these two directions is called magnetic declination.
When you are near the poles, the needle of your compass may become inaccurate or unusable due to disturbances in the magnetic field. It is recommended to use other means of navigation, such as Global Positioning Systems (GPS) or traditional techniques of navigation by stars or the sun.
A GPS receiver can be an excellent alternative near the poles, as it does not rely on magnetic field lines. However, keep in mind that low temperatures and extreme weather disturbances can temporarily affect the functioning of electronic devices. Therefore, it is advisable to have backup instruments and traditional navigation documentation.
The auroras borealis are caused by charged solar particles entering the atmosphere, which interact with the Earth's magnetic field. Although these phenomena generally do not directly disrupt a standard compass, the alterations or magnetic storms associated with the auroras can temporarily induce some disturbances in local magnetic fields, particularly pronounced near the poles.
The needle of a compass is magnetized and naturally reacts to the Earth's magnetic field. It aligns itself along the lines of force of the magnetic field, pointing towards magnetic North rather than geographic North, which is located near the North Pole.
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