Giant Magnetic Waves Have Been Discovered Oscillating Around Earth's Core

The interior of the Earth is far from serene. The globe rumbles under our surface activities, from plate tectonics to convection currents that move through the heated magmatic fluids deep beneath the crust.

Scientists monitoring Earth's satellite data have discovered something new inside the planet: a new form of magnetic wave that sweeps over the surface of our planet's core every seven years.

This finding might reveal how Earth's magnetic field is created, as well as information about our planet's thermal history and development, or the steady cooling of the planetary interior.

"Geophysicists have long theorized over the existence of such waves, but they were thought to take place over much longer time scales than our research has shown," says Nicolas Gillet of the Université Grenoble Alpes in France."

"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."

"We combined satellite measurements from Swarm, and also from the earlier German Champ mission and Danish Ørsted mission, with a computer model of the geodynamo to explain what the ground-based data had thrown up – and this led to our discovery."

For scientists, the Earth's magnetic field is a source of great intrigue. According to current research, the unseen structure creates a protective 'bubble' surrounding our planet, keeping dangerous radiation out and allowing life to flourish.

However, the magnetic field is not constant. It varies in strength, size, and shape, has characteristics we don't comprehend, and weakens with time.

The magnetic field originates inside our globe, which is why activity inside our planet is significant. A dynamo — a revolving, convecting, and electrically conducting fluid that transforms kinetic energy into magnetic energy, spinning a magnetic field out into space around the globe – produces it.

Inside Earth's outer core, that fluid is primarily molten iron.

The Swarm satellites are a trio of identical probes launched by the European Space Agency in 2013 and orbiting Earth to research the activity inside Earth, with a focus on the magnetic and dynamic activity originating from the core. Gillet and his colleagues uncovered the exciting new waves in this data.

They discovered a trend in data from different ground- and space-based observatories gathered between 1999 and 2021.

Huge magnetic columns aligned along Earth's rotating axis, greatest near the equator, make up magneto-Coriolis waves.

They migrate westward at a velocity of up to 1,500 kilometers (932 miles) each year, sweeping over the core-mantle barrier with an amplitude of roughly 3 kilometers (1.86 miles) per year.

Their presence implies that there may be more magneto-Coriolis waves with other oscillation periods that we have yet to find owing to a lack of data.

"Magnetic waves are likely to be triggered by disturbances deep within the Earth's fluid core, possibly related to buoyancy plumes," Gillet adds.

"Our research suggests that other such waves are likely to exist, probably with longer periods – but their discovery relies on more research."

For the time being, new discoveries might be utilized to investigate the interior of our planet in novel ways, including the core, which is difficult to study, and the core-mantle boundary, since waves transmit information about the medium through which they travel.