Scientists Discover New Layer in Earth’s Core

Sophie Hirsh - Author

Apr. 15 2021, Published 12:32 p.m. ET

Innermost Inner Core
Source: Getty Images

Throw away everything you learned in science class about the Earth’s layers. OK, not everything, but get ready to take in some pretty big info. Researchers have just discovered a new layer of the Earth, which they are calling the “innermost inner core.”

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This is a huge discovery — and the study, out of Australian National University (ANU) and published in the Journal of Geophysical Research: Solid Earth, is the first to provide proof of this hidden fifth layer. How will this discovery affect scientific research, school science classes, and more? Keep reading for everything you need to know.

earth innermost inner core layer
Source: Getty Images
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How many layers does the Earth have? Scientists just discovered a new one.

"Traditionally we've been taught the Earth has four main layers: the crust, the mantle, the outer core, and the inner core," lead author and ANU geophysicist Joanne Stephenson said in a statement on ANU's website. But now, there’s a new layer that’s deeper than the inner core: the innermost inner core.

"We found evidence that may indicate a change in the structure of iron, which suggests perhaps two separate cooling events in Earth's history," Stephenson said. "The details of this big event are still a bit of a mystery, but we've added another piece of the puzzle when it comes to our knowledge of the Earths' inner core."

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Despite the four-layer model that has been followed by scientists and taught in science classes, many scientists have wondered if the inner core was actually composed of two separate layers, according to Discover Magazine. "The idea of another distinct layer was proposed a couple of decades ago, but the data has been very unclear,” Stephenson added. 

Here’s how scientists discovered the Earth’s innermost inner layer.

"We got around this by using a very clever search algorithm to trawl through thousands of the models of the inner core,” Stephenson said. As explained by ScienceAlert, the search algorithm helped the team match thousands of models of the Earth’s inner core with copious data about how long it takes seismic waves to travel through Earth. 

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After examining models of the inner core's anisotropy ("having properties that differ that depend on the direction of measurement"), the study observed “a change at about 650 kilometers in the inner core — adding another piece to the puzzle,” Stephenson told Salon

“Importantly, what makes this study unique, is the vigorous treatment of uncertainty and the methods we used — we wanted to make sure what we saw in the inner was definitely a change and not just noise in the data,” she added.

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Will schools now teach students about the innermost inner layer of the Earth?

"[The findings are] very exciting — and might mean we have to rewrite the textbooks!" Stephenson said in statement.

That said, more research needs to be done before science teachers change their curriculums, according to Discover Magazine. Stephenson believes that further research into the innermost inner core will help us learn more about more about evolution and the history of our planet. Even though scientists can’t exactly travel to the innermost inner core of the Earth, hopefully we’ll soon see more research on the new layer.

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