Magnetic South Pole

Geographic North Pole

Magnetic North Pole

Rotation axis of the Earth

Geographic South Pole

Compass

This magnetic field plays an important role for life on our planet: it creates around our Earth a hollow space (the magnetosphere) that protects us against a part of the solar radiations (corpuscular radiations). (picture 2 & 3) This hollow space is however not hermetic. Some particles can enter the atmosphere at the North and the South Pole. (picture 4)

These particles, mainly electrons are the base of the southern and the northern light. The Earth’s magnetic field finds its origin in the center of the Earth (picture 5), where fast moving magma, full of iron and nickel changes the Earth into an enormous magnet. (picture 6)

At the surface, the magnetic field changes from place to place. This variation causes the movement of the needle in the compass whenever we move ourselves. It also is the reason why certain animals, like pigeons, can position themselves. The magnetic field varies in time as well. These variations are due to internal changes within the Earth, but also to electric storms in the high atmosphere. These changes in the ionized part of the atmosphere (the ionosphere) occur daily and happen more or less regularly. The variations associated with fluctuations in the core of the Earth, responsible for the relocation of the magnetic pole over the North Pole, are centuries old. Old magnetic fields can be found via traces in certain rocks or archeological objects, which form a sort of memory for time and place of their birth.

The magnetic field can vary quickly when the magnetosphere is disturbed by the changes in the solar activity (magnetic storms). These disturbances of our protecting hollow space are irregular and unpredictable. They can be the cause of power supply interruptions in large electricity distributors, of corrosion in pipelines or the breakdown of telecom satellites.