Why does Earth have a magnetic field at all?

Earth’s magnetic field is produced deep inside the planet by the geodynamo process. The outer core is a layer of liquid iron and nickel about 2,200 km thick, and its motion, combined with Earth’s rotation, generates electric currents. Those currents create the global magnetic field that protects the planet from much of the solar wind. The field is not fixed forever; it changes over time and has even reversed many times in geological history. Scientists study magnetic minerals in rocks to reconstruct these ancient reversals and the history of Earth’s core.