EARTH MAGNET. “The Earth generates its own magnetic field (the geomagnetic field), which is mostly caused by electric currents in the liquid outer core of the Earth (the “dynamo effect”). The magnetic field measured at the Earth’s surface is similar to the magnetic field one would expect to see if a large dipole magnet was placed in the center of the Earth.”
https://scholar.google.es/scholar?hl=en&as_sdt=0,5&as_ylo=2015&q=magnetoreception