In 2024, researchers transformed readings of an epic upheaval of Earth’s magnetic field flipping 41,000 years ago into an eerie, auditory experience.
Now a team containing some of those same scientists has sonified an even earlier flip, from epochs ago.
The resulting cacophony is an unnerving translation of geological data on the Matuyama-Brunhes reversal, a switching of the planet’s magnetic poles that took place roughly 780,000 years ago.
Geophysicists Sanja Panovska and Ahmed Nasser Mahgoub from the Helmholtz Centre for Geosciences (GFZ) created a global model of Earth’s magnetic field during the event, based on ancient magnetic data in sediments from drill cores around the world. This data was then visualized by Maximilian Arthus Schanner and sonified by Klaus Nielsen and Schanner.
Related: Earth’s Magnetic North Pole Is Officially Moving – Scientists Just Updated Its Location
Earth’s magnetic field is generated by the roiling liquid metals deep beneath the crust. Extending tens to hundreds of kilometers into space, the field deflects atmosphere-stripping particles, keeping us all safe below.
The bombardment of solar radiation that leaks through during reversals raises levels of beryllium-10 in Earth’s atmosphere, which in turn can be preserved in ice core samples. Measuring fluctuations in these isotopes then serves as a handy measure of the field’s weakening.
The data shows that when Earth’s magnetic poles get restless, they don’t just cleanly trade places, but stagger about in slow motion, splitting into blobs and drunkenly merging.
The resulting random bubbling of numerous magnetic polarities across the planet is aptly visualized in the animation.
Our early human ancestors, such as Homo erectus, lived through this event, which was thought to last up to 22,000 years (although this estimate is still debated).
It’s likely there were some kinds of consequences to our ancient relatives and other life on Earth at the time, since the magnetosphere protects us from cosmic and solar radiation. Other magnetic field wanderings have been linked to dramatic changes in climate.
But the exact consequences from almost 800,000 years ago remain unclear, as anthropological records around this time are sparse.
Boldly etched into the flow of solidifying lava across Earth, the Matuyama-Brunhes event is used by geologists as a marker of the beginning of the Middle Pleistocene. In sound form, it’s a haunting song that set the stage for the emergence of modern humans.