See a Reversal

Here, the entire animation plays without pausing.

The strength of our world's magnetic field has been diminishing for the past 300 years. If the Glatzmaier-Roberts model accurately simulates the processes that drive the magnetic field, the loss of strength could be an indication that a reversal is under way. This would be no surprise. On average, reversals of the Earth's magnetic field happen every 250,000 years. It's now been about 720,000 years since our last reversal. Judging from history, we know that a reversal is long overdue. But there's no need to throw away your old compasses. A reversal usually takes hundreds or thousands of years to complete.


Back Next



x
NOVA PBS