It may be time to rewrite the textbooks, as scientists have discovered the Earth has a ‘fifth layer’ in the form of an innermost inner core at the center of the planet.

  • Researchers created an algorithm to search through data on the Earth’s core
  • They found evidence of a ‘boundary line’ where iron has a different structure
  • This suggests there is an innermost inner core sitting at the center of the Earth
  • It may have been the result of a major event at some point in the Earth’s history 

While most of us take the ground beneath our feet for granted, written within its complex layers, like pages of a book, is Earth’s history. Our history.

Now researchers have found more evidence for a whole new chapter deep within Earth’s past – Earth’s inner core appears to have another even more inner core within it.

There’s probably a fifth layer. (forplayday/iStock/Getty Images)

“Traditionally we’ve been taught the Earth has four main layers: the crust, the mantle, the outer core and the inner core, but a fifth layer has been suspected for more than a decade but proved near impossible to detect.” explained Australian National University geophysicist Joanne Stephenson. 

Our knowledge of what lies beneath Earth’s crust has been inferred mostly from what volcanoes have divulged and seismic waves have whispered.

From these indirect observations, scientists have calculated that the scorchingly hot inner core, with temperatures surpassing 5,000 degrees Celsius (9,000 Fahrenheit), makes up only one percent of Earth’s total volume.

Now Stephenson and colleagues have found more evidence Earth’s inner core may have two distinct layers.

“It’s very exciting – and might mean we have to re-write the textbooks!” she added.


The findings were published in the Journal of Geophysical Research.  



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