Scientists say they’ve found a “whole new hidden world” at the Earth’s core.
The centre of the Earth has long been believed to be a solid ball of iron, surrounded by a super-hot molten outer core.
But new research from US and Japanese based seismologists reveals that the story is much more complex, with multiple layers of hard metal, liquid metal and a certain amount of material that’s halfway between the two.
No humans, or even machines, could venture to such depths. But Rhett Butler, from the University of Hawaii and his colleague Seiji Tsuboib who works at Japan’s Centre for Earth Information Science and Technology, studied how shear waves created by earthquakes move through the globe.
"Illuminated by earthquakes in the crust and upper mantle,” Butler said, “and observed by seismic observatories at Earth's surface, seismology offers the only direct way to investigate the inner core and its processes.
The distribution of the waves operated as a kind of “sonar” exposing the inner structure of the planet in detail.
Butler said that there were successive layers of “of hard, soft, and liquid or mushy iron alloys in the top 150 miles of the inner core”.
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He told Science Daily that the research shed new light on the “composition, thermal history, and evolution of Earth”.
He said that the research was of more than just academic interest.
The Earth’s core is the engine of the magnetic field that prevents our planet becoming an irradiated desert like Mars.
"Knowledge of this boundary condition from seismology may enable better, predictive models of the geomagnetic field which shields and protects life on our planet," Butler said.
Seismologist Jessica Irving from the University of Bristol told Live Science that "We're finding a whole new hidden world" at the Earth’s core.
It may not be the dinosaur-filled hidden world described by Jules Verne in 1871, but the very real “hidden world” beneath our feet will provide scientists with fascinating material for years to come.
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