A jet stream within the Earth's molten iron core has been discovered by scientists using the latest satellite data that helps create an 'x-ray' view of the planet.

Lead researcher Dr Phil Livermore, from the University of Leeds, said: "The European Space Agency's Swarm satellites are providing our sharpest x-ray image yet of the core. We've not only seen this jet stream clearly for the first time, but we understand why it's there."

"We can explain it as an accelerating band of molten iron circling the North Pole, like the jet stream in the atmosphere," said Dr Livermore, from the School of Earth and Environment at Leeds.

Because of the core's remote location under 3,000 kilometres of rock, for many years scientists have studied the Earth's core by measuring the planet's magnetic field -- one of the few options available.