Open Questions: Earth's Magnetic Field

Geomagnetic flip: Summary of April 2004 article from Physics World. "Earth is a laboratory for a vast array of natural phenomena. One of the most fascinating of these is the way that the planet's magnetic field changes over time. We know that the Earth last reversed its north and south magnetic poles about 778 000 years ago, although analyses of the magnetization of geologic materials suggest that our planet has tried to reverse its polarity several times since then. This might seem like a long time but it is really only moments ago in the three plus billion year history of the Earth's magnetic field."
Mini Earth created in the lab: May 2000 news article from Physics World, about a laboratory dynamo mechanism that produces the Earth's magnetic field.
Earth's poles may switch: January 1999 news article from Physics World, about a prediction that Earth's magnetic poles may flip in the next 1000 years.

North by Northwest
Sid Perkins
Science News, December 22, 2007: The planet's wandering magnetic poles help reveal history of Earth and humans.