Scientists say they have identified a remarkable new feature in Earth’s molten outer core.
They describe it as a kind of "jet stream" - a fast-flowing river of liquid iron that is surging westwards under Alaska and Siberia.
The moving mass of metal has been inferred from measurements made by Europe’s Swarm satellites.
This trio of spacecraft are currently mapping Earth's magnetic field to try to understand its fundamental workings.
The scientists say the jet is the best explanation for the patches of concentrated field strength that the satellites observe in the northern hemisphere.
"This jet of liquid iron is moving at about fifty kilometres per year," explained Dr Chris Finlay from the National Space Institute at the Technical University of Denmark (DTU Space).
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