Sun Compass
Magnetic compasses have limited use in Antarctica and the Arctic for several reasons. First, there is not one but three poles: the geographic, the geomagnetic and the magnetic.
A Sun compass that was made and used on the British Terra Nova Antarctic Expedition of 1910-13 (x)
The geographic pole is what we all know as the North or South pole. So now the magnetic and geomagnetic poles are not in the same place as the geographic pole - in fact they are both kilometres away from each other and the distance is increasing every year. Now the compass is attracted to the magnetic pole, and if you are too close to the geographic and magnetic poles, there will be a large deviation between the two points, which will irritate the compass so much that it will go in the wrong direction. When you are directly over a magnetic pole, the needle of the compass no longer rotates to point at the pole, but tries to point straight up or down because the magnetic field at that point is vertical. If the compass does not have an appropriate counterweight, the compass needle can break on the housing. Therefore, it is difficult to use a magnetic compass in these places, so a solar compass was used in these places.
This one above is made of wood and has a handwritten paper disc glued to the top. The disc is divided into two 12-hour sets (a.m. and p.m.) and also has red compass markings around the outside. In the centre of the circle is a hole into which a needle was originally inserted to cast a shadow on the compass face, similar to the gnomon of a sundial. This can be used to tell the time if the meridian is known, or the meridian if the time is known. It can be set using a watch chronometer and held in the hand during the march. But if you think that this type of compass was invented in the 19th century during the great Arctic and Antarctic expeditions, you are actually wrong because this type of navigation aid was already known to the Vikings.
