Something strange and unexplained is happening far beneath our feet.
According to a recent study by European astronomers, for 20 years satellites have been picking up “interannual geomagnetic field changes” emanating from the Earth’s core, without explanation. Now, researchers have used data from a trio of Swarm satellites from the European Space Agency to identify a new and “mysterious” type of magnetic wave that sweeps across the surface of Earth’s core—where the core meets the mantle—every seven years. According to the study, these waves account for a “significant part” of the unexplained signal.
“Geophysicists have long theorised over the existence of such waves, but they were thought to take place over much longer time scales than our research has shown,” said study lead author Nicolas Gillet, from the University Université Grenoble Alpes, in an ESA press release.
“Measurements of the magnetic field from instruments based on the surface of Earth suggested that there was some kind of wave action, but we needed the global coverage offered by measurements from space to reveal what is actually going on,” he said.
Earth’s magnetic field sustains life on our planet by protecting us from cosmic radiation and other threats. It emanates from liquid iron in the core, and it’s still rather mysterious, with constant fluctuations and a current phase of weakening that scientists are seeking to explain. Because of the important role that Earth’s magnetic field plays in the survival of all planetside life, understanding it is of chief importance. The only practical way to globally analyse activity in the core is with readings from space, which is where the ESA’s Swarm mission comes in.
“Magnetic waves are likely to be triggered by disturbances deep within the Earth’s fluid core, possibly related to buoyancy plumes,” Gillet explained in the release. “Each wave is specified by its period and typical length-scale, and the period depends on characteristics of the forces at play. For [the type of newly-identified wave], the period is indicative of the intensity of the magnetic field within the core.”
The identification of the new wave that sweeps our planet’s core is a fascinating finding, but it doesn’t totally explain those “interannual” magnetic field changes that have puzzled scientists for decades. Still, the observations and theoretical advancements made as part of the study will help to make further discoveries.
“Our research suggests that other such waves are likely to exist, probably with longer periods—but their discovery relies on more research,” Gillet said.
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