hidden structure in earths core
Julie Hambleton
Julie Hambleton
January 5, 2024 ·  2 min read

Scientists Detect Signs of a Hidden Structure Inside Earth’s Core

Do you remember learning about the structure of the Earth in grade school? You were likely told that the Earth comprises four main layers: The inner core, outer core, mantle, and crust. Scientists from the Australian National University (ANU) have found evidence that our planet’s inner core might have a hidden structure of two unique layers. (1)

Earth’s Inner Core Might Have A Hidden Structure Inside It

Geophysicist Joanne Stephenson and her colleagues from ANU studied the Earth’s layers when they realized: The Earth’s innermost core might contain a hidden structure. Essentially, instead of being one layer, it may actually be divided into two distinct parts. (1)

“Traditionally, we’ve been taught the Earth has four main layers: the crust, the mantle, the outer core, and the inner core,” she said. “It’s very exciting – and might mean we have to re-write the textbooks!” (2)

How They Discovered This Hidden Structure

Studying the Earth’s structure is not easy. Most of what we know until this point, we have learned from what volcanoes and earthquakes can show us. These, however, are indirect observations. After all, the Earth’s inner core is hot – temperatures above 9,000F hot. Scientists predict that the inner core makes up only about 1% of the Earth’s total volume. (1)

To study the inner core further, Stephenson and her team used a specially-designed search algorithm to find thousands of inner core models. The algorithm then found observational data that spanned several decades about how long it takes seismic waves (the things that cause earthquakes) to travel through Earth. Finally, the algorithm matched all the information together. (2)

What They Found Down There

The research team studied what’s called the Earth’s anisotropy. This is the effect that the differences in the Earth’s make-up have on the properties of seismic waves. What they found is that some of the materials were more likely to affect them than others. (3)

The various models all come to different conclusions about how seismic waves travel through the Earth. The study could not show the depth of the inner core, but it did find some angular changes. (1)

“We found evidence that may indicate a change in the structure of iron, which suggests perhaps two separate cooling events in Earth’s history,” said Stephenson. “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.” (2)

Her team’s findings explain why experimental evidence hasn’t always matched up properly with our current model of the Earth’s layers. (1)

Though there are still gaps in the data, geologists are currently developing a new method to study the Earth’s core that will hopefully provide this information. (2)

Keep Reading: By The End Of The Century, Humanity Might Get A Lot Dumber


  1. Evidence for the Innermost Inner Core: Robust Parameter Search for Radially Varying Anisotropy Using the Neighborhood Algorithm.” AGU Pubs. J. Stephenson, H Tkalčić M. Sambridge. December 7, 2020.
  2. Scientists Detect Signs of a Hidden Structure Inside Earth’s Core.” Science Alert. Tessa Koumoundouros. March 4, 2021.
  3. Anisotropy.” Britannica