This morning I was asked to settle an argument about the Magnetic North Pole being a magnetic south pole. That discussion started me wondering about the dynamo theory, widely accepted now, that the Earth's swirling, agitating liquid outer core, interacting through convection with Earth's inmost magnetism, is what regenerates our planet's geomagnetic field.

Earth's inner core of solid iron, at approximately 4000°C is too hot to sustain magnetism through eons of geologic time, by itself.

Recently I was surprised to read that, since 1989, The Magnetic North Pole's migration towards Russia has sped up, from about nine to almost 40 miles per year.  A deep magnetic plume may be stirring up a region of rapid magnetic change on the surface, which may be pulling the pole away from Canada, according to geophysicist Arnaud Chulliat of the Institut de Physique du Globe de Paris in France.

After Earth's poles and magnetic field were squared away, this morning's conversation drifted to the magnetic fields of other planets.

But what about Earth's churning geodynamo?

We cannot journey 4000 miles down into the center of the Earth to collect data. But Gary A Glatzmaier, Professor of Earth and Planetary Sciences at the University of California, Santa Cruz, and his colleague Paul Roberts, Professor of Mathematics at UCLA, innovated a 3-D supercomputer simulation and observed results that confirm much of the dynamo theory.

A supercomputer model of flow patterns in Earth's liquid core, by Dr. Gary A. Glatzmaier - Los Alamos National Laboratory - U.S. Department of Energy, via Wikimedia Commons

After setting the simulation's parameters to correlate with dynamo theory scenarios and letting it run for almost a year, which represented over 36,000 years of ordinary time, the Glatzmaier-Roberts computer model generated a magnetic field reversal.  This image shows a supercomputer model of flow patterns in Earth's liquid core before magnetic pole reversal.

Geomagnetic reverals have been confirmed by geological records to happen on Earth at varying, infrequent intervals. The supercomputer simulation matched other measured features of Earth's magnetic field, as well.

What I read today that was new to me, is that Earth's inner and outer cores have opposite polarities. This balance prevents geomagnetic reversals from happening more often and it also means that, on some level, everyone arguing about north and south over breakfast this morning was right.