It is an experimental fact that the strength of a magnetic field is inversely proportional to the temperature of the field generator. Can we conclude from this that the hotter an object is, the weaker is its magnetic field. Conversely, the colder an object is, the stronger is its magnetic field. This could mean that the magnetic field in the interior of planets and stars is very weak. Since the vacuum is very cold, its magnetic field must be very strong. This field is strong enough to drive the motion of cosmic radiation, to which its origin is still not clearly determined.