Scientists from the University of Leeds and Technical University of Denmark discovered what appears to be jet stream moving at more than 40 kilometers per year within the Earth's molten core under 3,000 kilometers of rock.

Their findings, published in the journal Nature Geosciences, showed that the speed of the jet stream is causing changes in the Earth's magnetic field. At a speed of over 40 kilometers per year, this jet stream is three times faster than typical outer core speeds and hundreds of thousands times faster at which the Earth's tectonic plates move.

"We've not only seen this jet stream clearly for the first time, but we understand why it's there," said Phil Livermore, a researcher at University of Leeds' School of earth and Environment, in a press release. "We can explain it as an accelerating band of molten iron circling the North Pole, like the jet stream in the atmosphere."

For the study, the researchers used latest data from the European Space Station's (ESA) Swarm mission to create the sharpest x-ray image yet of the Earth's core. The Swarm mission of the ESA involves three satellites simultaneously measuring and untangling different magnetic signals coming from the Earth's core, mantle, crust, oceans, ionosphere and magnetosphere, providing the clearest information yet about the magnetic field created in the core.

The researchers found jet stream aligned with the boundary between two regions of the core. The researchers noted that the liquid in the core moving toward the boundary from both sides, which is squeezed out sideways, is likely the cause of the jet stream.

The liquid in the core is likely to be forced in the boundary by buoyancy or changes in the magnetic field within the core. The researchers noted that the Earth's magnetic field is ever changing and could even change in a way that it will reverse the flow of the jet stream.