What is a compass?

What is a compass?

A compass is an instrument that, thanks to its immersed needle that rotates on an axis and points to the north magnetic pole, makes it possible to determine the directions of earth's surface.
Photo of Compass next to a drawing of an electrical circuit.

According to historians, the compass was invented in China during the 9th century. Initially, it consisted of an immersed needle that floated inside a container of water. Over time, the size of the artifact was reduced in order to move it more conveniently. Thus arose the axis on which the needle rotates and a wind rose was added to calculate the directions.

The compasses remained almost unchanged over time. Today, satellite navigation systems (such as GPS) have virtually replaced compasses by offering greater accuracy and more detailed data (the coordinates). In any case, compasses are still used for possible failures and/or imperfections of more complex systems and in places where there is no electrical power or the possibility to change batteries.

It is important to bear in mind that the north magnetic pole to which the compass needle points is different from the geographic north and varies according to the region of the planet. At the poles, both north and south, compasses are useless, as the lines of force of the Earth's magnetic field converge there.

The concept of a compass can also be used metaphorically to refer to any person or object that is useful or helpful to someone.