This chink in the planet's armor of geomagnetic energy is located above the southern Atlantic Ocean, so scientists have appropriately dubbed it the South Atlantic Anomaly.

"The new, eastern minimum of the South Atlantic Anomaly has appeared over the last decade and in recent years is developing vigorously," Jürgen Matzka, from the German Research Center for Geosciences, said in a press release last week.

Earth's magnetic field exists thanks to swirling liquid iron in the planet's outer core, some 1,800 miles beneath the surface.

Anchored by the north and south magnetic poles (which tend to shift around and even reverse every million years or so), the field waxes and wanes in strength, undulating based on what's going on in the core.

If you imagine the magnetic field as a series of rubber bands that thread through the magnetic poles and the Earth's core, then changes in the core essentially tug on different rubber bands in various places.