Currently, Earth's geographic poles and magnetic poles are roughly in the same region; when the arrows in our compasses point north, they point in the general direction of the North Pole. But this hasn't always been the case. Scientists now know that our planet's magnetic poles have flipped on several occasions. There were times in the distant past when our compasses would have pointed south instead of north.
In fact, there has been some speculation among scientists that we might be on the verge of another one of these shifts. Over at least the last 200 years, Earth's magnetic field has been weakening, magnetic north has been wandering, and an identified weak area in the Earth's magnetic field (called the South Atlantic Anomaly) has been growing.
Furthermore, when we look back through history, there's evidence that pole reversals happen about once every 450,000 years. The last one? 780,000 years ago. So, we might be due for one, and that's not likely to be a good thing.
Scientists disagree about what such a shift could mean for us, but possible outcomes range from technological annoyances (our navigational equipment would go haywire, for instance) to mass extinction. That's not exactly a spectrum we want to have to gamble with.
How likely is this to happen?
A new study published in the Proceedings of the National Academy of Sciences offers some relief from these fears, however. New models based on data collected on previous pole reversals and pole excursions (times when the poles almost reversed, but didn't) seems to suggest that the magnetic changes currently happening are mild by comparison, reports Phys.org.
"There has been speculation that we are about to experience a magnetic polar reversal or excursion," explained researcher Richard Holme from the University of Liverpool. "However, by studying the two most recent excursion events, we show that neither bear resemblance to current changes in the geomagnetic field and therefore it is probably unlikely that such an event is about to happen."
Holme continued: "Our research suggests instead that the current weakened field will recover without such an extreme event, and therefore is unlikely to reverse."
So that's good news, but we aren't totally out of the woods. Because the magnetic field shields the Earth from solar winds and harmful cosmic radiation, a weakening magnetic field could still have some unfavorable consequences for us, even if a complete flip is unlikely. It's a reminder of just how fragile our little blue dot is in the cacophony of the cosmos all around us. Our protective shell is a thin one indeed.