The Earth’s continuously changing magnetic field surrounds the planet like an invisible force field – deflecting highly charged solar particles. Reversals are the rule, not the exception. Earth has settled in the last 20 million years into a pattern of a pole reversal about every 200,000 to 300,000 years, although it has been more than twice that long since the last reversal, the Brunhes-Matuyama, that occurred around 780,000 years ago. A temporary reversal, the Laschamp event, occurred around 41,000 years ago, and lasted less than 1,000 years with the actual change of polarity lasting around 250 years. Our planet’s history...