Scientists discover massive solid metal ball inside Earth’s core

And it's 400 miles thick

Previously, there were only four: the crust, mantle, liquid and the solid inner core.

But a pair of seismologists at the Australian National University have found there is a distinct layer within Earth's inner core. And it's a solid, 400-mile-thick, solid, metallic ball.

The study found the ball has a different crystal structure that causes shock waves from earthquakes to reverberate through the layer at different speeds than the surrounding core.

“Clearly, the innermost inner core has something different from the outer layer,” said Thanh-Son Pham, lead author of the study, told the Washington Post.

“We think that the way the atoms are [packed] in these two regions are slightly different.”

The seismologists believe the new core was created following a "significant global event from the past".

Thanh-Son Phạm and Hrvoje Tkalčić discovered the solid metal core by studying specific earthquakes and monitoring "seismic waves reverberating through the entire planet". The researchers analysed data from about 200 magnitude-6 and above earthquakes from the last decade.

This allowed them to spot details that had previously gone unnoticed.

As well as confirming the existence of the solid metal core, also known as an "innermost inner core" or IMIC, they also made another discovery. It was 400-miles in diameter.

Despite still being made of same materials to the molten core, the metal inner core may also have different properties, explained the scientist. “We think that the way the atoms are [packed] in these two regions are slightly different,” Thanh-Son Pham said, adding that this means seismic waves travel through it at a different rate.

The metal core, the scientists believe, could be key to understanding how life evolved on planet earth.

They added that the metal inner core could be a "fossilised record" of a significant tectonic event, with the core solidifying shortly afterwards.

Writing in The Conversation, the researchers said: “Studying Earth’s center is not just a topic of academic curiosity, but something that sheds light on the very evolution of life on our planet’s surface."

Read the report here.

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