Scientists understand that Earth's magnetic field has flipped its polarity many times over the millennia. In other words, if you were alive about 800,000 years ago, and facing what we call north with a magnetic compass in your hand, the needle would point to 'south.'

A new study in the journal Geophysical Research Letters has confirmed previous theoretical predictions that the churning cauldron of molten metals that make up Earth's liquid outer core is slowly being stirred by a very complex but predictable series of periodic oscillations.

Every so often, Earth's magnetic field flips on its head, turning the magnetic North Pole into the South Pole and vice versa. It last happened 780,000 years ago, and is predicted to occur again in about 1,500 years ... maybe.

By Brownlee, Christen MICROBIOLOGY Some aquatic bacteria that orient themselves using Earth's magnetic field swim in the opposite direction from what researchers typically expect, calling into question a longstanding theory of what this navigational behavior accomplishes.

Earth's north magnetic pole is drifting away from North America and toward Siberia at such a clip that Alaska might lose its spectacular Northern Lights in the next 50 years, scientists said Thursday.