Flipping Magnetic Fields
North and south. We take these directions for granted. Pull out a compass and the needle will swing to the north in response to the magnetism in the Earth's crust. The magnetic poles roughly coincide with the axis of the Earth's rotation. But some scientists believe that the Earth's magnetic field has reversed itself several times within geological history, with the North and South pole swapping polarity.
The Earth's magnetic field is continuously created through the effect of the Earth's rotation on the semi-liquid iron core. It is an ongoing process where a general equilibrium is achieved between the Earth's center core and outer core. Just what causes the polarity to flip, if indeed it really does at all, is thought to relate to the interactions between the center and outer core with minor fluctuations causing a cascading effect resulting in a flipping of the polarity. This flipping may occur over a very short period of time, or over several hundred years. Imagine what confusion would occur if the poles were to flip today. Our entire directional orientation is based on the current polarity. Not only that, but the Earth's magnetic field shields us from cosmic radiation. If a reversal does occur, we might have more to worry about than readjusting our compasses.
