  A thermodynamic model for the generation of magnetic fields in the planets is
proposed, considering crossed effects between gravitational and electric
forces. The magnetic field of the Earth is estimated and found to be in
agreement with the actual field. The ratio between the field of several planets
and that of the Earth is calculated in the model and compared with the same
ratio for the measured fields. These comparisons are found to be qualitatively
consistent. Once the value of the magnetic field is calculated, the model is
used to obtain the tilt of the magnetic dipole with respect to the rotation
axis. This model can explain why Uranus and Neptune magnetic fields have higher
quadrupole moment than the other magnetic fields of the Solar System and why
Saturn, that has a highly axysymmetric field, has lower quadrupolar component.
The model also explains the double peak of the magnetic field observed by
Voyager 2 while recording the field of Neptune. The Earth paleomagnetic data
are analysed and found to be consistent with the model, that predicts higher
quadrupole components for the more tilted dipoles. A field is predicted for all
the planets and satellites of the Solar System with enough mass. Objections are
made to the theories that predict that this effect could not generate a field
agreeing with the measured one.
