Earth’s geomagnetic field wraps the planet in a protective layer of energy, shielding us from solar winds and high-energy particles from space. But it’s also poorly understood, subject to weird reversals, polar wandering, and rapidly changing intensities. Now a chance discovery from an archaeological dig near Jerusalem has given scientists a glimpse of how intense the magnetic field can get—and the news isn’t good for a world that depends on electrical grids and high-tech devices.
In a recent paper for Proceedings of the National Academy of Sciences, an interdisciplinary group of archaeologists and geoscientists reported their discovery. They wanted to analyze how the planet’s geomagnetic field changes during relatively short periods, and they turned to archaeology for a simple reason. Ancient peoples worked a lot with ceramics, which means melting clay to the point where the iron oxide particles in the dirt will float freely, aligning themselves with the Earth’s current magnetic field.