Summary
If we observe the Earth's magnetic field, everything happens as if there were a gigantic magnetic bar at the heart of our planet running approximately along its axis of rotation, with at its ends the south pole and the magnetic north pole. But one has to look below the surface, as shown by Jean-Pierre Valet, a paleomagnetician at the Institut de Physique du Globe de Paris (Paris geophysical institute - IPGP), who tells us what is really going on under our feet.
