Scientists discover 'hidden structure' in Earth's core which could 'rewrite the textbooks'

It’s not hard to see why there are so many conspiracy theories about what lies beneath our feet.

The surface of the Earth – the crust – on which we live makes up a mere one per cent of the planet’s volume, and it’s impossible to dig down deep enough to know for sure what lies within its underbelly.

However, for years, scientists have had at least a broad idea of the main layers that make up the world: the crust; the mantle; the outer core and the inner core.

And yet, recent research suggests we may have to update this long-established structure.

A study , led by Australian National University geophysicist Joanne Stephenson, posits that the Earth’s inner core may, in fact, have two distinct layers.

"It's very exciting – and might mean we have to rewrite the textbooks!" Stephenson said at the time of the paper’s publication back in 2020.

She and her team used seismic data and a search algorithm to draw their conclusion. They analysed different models of the inner core’s anisotropy – how differences in its makeup affect seismic waves – and made some pretty groundbreaking observations.

"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 explained.

"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 Earth's inner core."

It’s not the first time scientists have suspected the existence of an innermost layer, with previous research suggesting that the iron crystals comprising the inner core have different structural alignments, as Science Alert notes.

Nevertheless, "we are limited by the distribution of global earthquakes and receivers, especially at polar antipodes," Stephenson and her colleagues wrote in their paper, acknowledging that the missing data undermines the certainty of their conclusions.

Still, their findings align with other studies on the composition of the innermost inner core.

The hope is now that future research will fill in some of these data gaps and allow scientists to determine, once and for all, whether or not those textbooks really do need a rewrite.

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