Magnetism, Electricity and This Planet

Our planet's magnetic field has existed for billions of years, yet Earth isn't a permanent magnet: the field would disappear in just 100,000 years, if it weren't being regenerated from the core.  This generator is the geodynamo.

Earth's core of liquid iron circulates in a spiral flow, powered by thermal convection and twisted by the Coriolis forces of its rotation.  Huge electric currents arise from this rotation, and these produce the field.

The field lines are neat at the Earth's surface, forming the poles we're familiar with.  In the liquid core, turbulence pulls the field into a wild knot of spaghetti.

Predicting the Big Flip

In 1995 Gary Glatzmaier (University of California Santa Cruz) and Paul Roberts (UC Los Angeles) created the first self-consistent time-dependent simulation of this process in 3D.  Their model works: by using massive computing power in a purely numerical model, it predicts Earth's poles along with its dynamic internal structure. (It also predicts flips in the magnetic field: as in life, every few hundred thousand years, the North pole becomes South.  Movies are here.)

This crystal is a 3 1/8" cube etched with a snapshot of the Glatzmaier-Roberts Geodynamo.  And there's a translucent sphere at the planetary surface, just so you'll know where you stand.

Deep Structure