Geomagnetism

Geomagnetism refers to the Earth’s magnetic field, which extends from the Earth’s interior to where it meets the solar wind. Roughly speaking, it is the field of a gigantic bar magnet currently tilted about 10 degrees off the Earth’s rotational axis. Unlike a bar magnet, however, the Earth’s magnetic field changes over time, because it is generated by a geodynamo. Relatedly, geomagnetic reversals are shifts in Earth’s magnetic field in which the positions of the magnetic north and south are switched. In modern times, a reversal has usually occurred every 50,000 to 800,000 years, with an average of 200,000 years. A plethora of scientific evidence supports the existence of geomagnetic reversals.