The geodynamo for non-geophysicists

The geodynamo usually appears as a somewhat intimidating subject. Its understanding seems to require knowledge of the intricate theory of magnetohydrodynamics. The solution of the corresponding equations can only be achieved numerically. It seems to be a subject for the specialist. We show that one can understand the basics of the functioning of the geodynamo solely by using the well-known laws of electrodynamics. The topic is not only important for geophysicists. The same physics is the cause for the magnetic fields of Sun-like stars, of the very strong fields of neutron stars, and also of the cosmic magnetic fields. (paper)