Yesterday, I showed you a great video of NASA scientists explaining how magnetic fields work over beautiful animations making the fields come to life. Today, now that you're all caught up on how the fields work, I'll show you how geophysicist Dan Lathrop is building a fake planet filled with liquid sodium that will, if all goes according to plan, end up with a magnetic field of its own.

The 10-foot-tall, 26-ton steel ball will spin at a high speed of 80MPH at its equator when it's fully operational. The idea is that our planet gets its magnetic field from the core, a quickly spinning ball of liquid metal, probably liquid iron. Because iron only melts at seriously high temperatures — this is the center of the Earth we're talking about, after all — Lathrop is using liquid sodium instead.

Hopefully, when it's heated up and starts spinning, the liquid sodium will slosh around in some sort of "organized turbulence," with an overall pattern emerging in how it sloshes around. This will make it like a tiny working model of the center of the Earth, giving us a much better understanding of what goes on down there and just how it controls the magnetic field that makes all compasses point to the North Pole. [Neatorama via NPR]