The Earth behaves like a gigantic magnet. For the reason it is possible to find one’s direction with the aid of a compass. Since the early modern era, scientists carry out experiments to understand the secret of magnetism and its role as a characteristic of our planet. Models based on technical experience and laboratory experiments lead to ever new insights. Today, one assumes that the Earth operates like a sort of dynamo. The largest part of the Earth’s magnetic field is generated by the outer liquid core, which is composed mainly of iron. The Earth’s magnetic field protects humankind from dangerous radiation from space.

René Descartes, Prinicipia philosophiae