Just what sustains Earth's magnetic field anyway?

Earth's magnetic field shields us from deadly cosmic radiation, and without it, life as we know it could not exist here. The motion of liquid iron in the planet's outer core, a phenomenon called a "geodynamo," generates the field. But how it was first created and then sustained throughout Earth's history has remained a mystery to scientists. New work published in Nature from a team led by Carnegie's Alexander Goncharov sheds light on the history of this incredibly important geologic occurrence.