A Colossal Jet-Stream of Molten Iron as Hot as the Sun Revealed Revealed by X-Ray Satellite Flowing Under Alaska and Siberia

 

Earth-space

 

 

 

A colossal jet stream, a river of molten iron has been found surging under Alaska and Siberia which is estimated to be about 420 km wide (260 miles) some some 3,000 kilometers (1,864 miles) below the surface and nearly as hot as the surface of the Sun, has tripled in speed in less than two decades, and is now headed towards Europe.


"We know more about the Sun than Earth’s core," says one of the team, Chris Finlay from the Technical University of Denmark. "The discovery of this jet is an exciting step in learning more about our planet’s inner workings." Finlay and his team detected the jet stream while analyzing data from the European Space Agency’s (ESA) trio of satellites, called Swarm.

"The European Space Agency's Swarm satellites are providing our sharpest x-ray image yet of the core," said Phil Livermore, from the University of Leeds. "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." 

Because of the core's remote location under 3,000 kilometers 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. Previous research had found that changes in the magnetic field indicated that iron in the outer core was moving faster in the northern hemisphere, mostly under Alaska and Siberia.

Launched in 2013 to measure fluctuations in Earth's magnetic field, these satellites allowed the researchers to create a kind of x-ray of the planet’s inner structure, revealing vast components that we didn’t even know existed before.

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

Earth's magnetic field is thought to be generated by the activity going on deep inside the planet’s core. The core itself is a solid lump, two-thirds the size of the Moon, and composed mainly of iron. With a temperature of around 5,400 degrees Celsius (9,800 degrees Fahrenheit), it’s almost as hot as the surface of the Sun, which hits an intense 5,505 °C (9,941 °F).

Surrounding the solid inner core is Earth's outer core – a 2,000-km-thick (1,242-mile) layer made primarily of liquid iron and nickel. Differences in temperature, pressure, and composition in this layer create movements and whirlpools in the liquid metal, and together with Earth’s spin, they generate electric currents, which in turn produce magnetic fields.

When the researchers examined satellite data from the outer core area in the northern hemisphere, they found strange 'lobes' of magnetic flux beneath Alaska and Siberia.

But the lobes weren't stuck in those positions – they're moving in the direction of the European continent, and the team says they're being pushed along by a jet stream of molten iron.

"Because their motion could originate only from the physical movement of molten iron, the lobes served as markers, allowing the researchers to track the flow of iron," Andy Coghlan reports for New Scientist.

But new data from the Swarm satellites has revealed these changes are actually caused by a jet stream moving at more than 40 kilometres per year.

This is three times faster than typical outer core speeds and hundreds of thousands of times faster than the speed at which the Earth's tectonic plates move.

Evolution of the magnetic field at the edge of the Earth's core 1999-2016. Credit: Nature Geoscience (2016) and Phil Livermore.

 

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The European Space Agency's Swarm mission features a trio of satellites which simultaneously measure and untangle the different magnetic signals which stem from Earth's core, mantle, crust, oceans, ionosphere and magnetosphere. They have provided the clearest information yet about the magnetic field created in the core.

The study, published today in Nature Geoscience, found the position of the jet stream aligns with a boundary between two different regions in the core. The jet is likely to be caused by liquid in the core moving towards this boundary from both sides, which is squeezed out sideways.

"Of course, you need a force to move the liquid towards the boundary," said co-author Rainer Hollerbach, from the School of Mathematics at Leeds. "This could be provided by buoyancy, or perhaps more likely from changes in the magnetic field within the core."

"Further surprises are likely," said Rune Floberghagen, ESA's Swarm mission manager. "The magnetic field is forever changing, and this could even make the jet stream switch direction.

"This feature is one of the first deep-Earth discoveries made possible by Swarm," said co-author Dr Chris Finlay, from the Technical University of Denmark With the unprecedented resolution now possible, it's a very exciting time – we simply don't know what we'll discover next about our planet. We know more about the Sun than the Earth's core. The discovery of this jet is an exciting step in learning more about our planet's inner workings."

The Daily Galaxy University of Leeds

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