Earth's magnetic field is weakening at 10 times the rate experts thought it was—and that could mean a reversal of the magnetic north and south poles could be coming sooner than expected. But don't panic just yet: Scientists are talking in terms of some 2,000 years, Scientific American reports. The magnetic field has been weakening at a rate of about 5% every decade, as opposed to 5% every century, as had been believed. The field, LiveScience notes, protects us from solar radiation.
Such polar flips remain somewhat mysterious, but they're linked to the movement of iron at the planet's center. That movement is occasionally disrupted for reasons that aren't clear; this leads to weakening of the magnetic field, and, in some cases, a reversal of the poles. That process takes an average of 5,000 years, Scientific American reports, and it last happened 780,000 years ago. It's probably nothing to worry about, the publication notes: There's no sign of a crisis in the fossil record during previous reversals. As for the solar protection, scientists haven't seen evidence that the field has ever totally disappeared, NASA reports. (Read more Earth stories.)