Beneath our feet: The last element in the Earth's core has been identified

The International Space Station is seen with the docked space shuttle Endeavour in this photo provided by NASA and taken May 23, 2011. The photo was taken by Expedition 27 crew member Paolo Nespoli from the Soyuz TMA-20 following its undocking and is the first-ever image of a space shuttle docked to the International Space Station.     REUTERS/NASA/Handout (UNITED STATES - Tags: SCI TECH) FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY. IT IS DISTRIBUTED, EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS - RTR2NEY1

Scientists may have discovered the 'missing element' deep inside Earth's core. Image: REUTERS/NASA

Lindsay Dodgson
Reporter, Business Insider
A hand holding a looking glass by a lake
Crowdsource Innovation
Get involved with our crowdsourced digital platform to deliver impact at scale

It's generally well known that the innermost part of Earth is made mostly of iron (about 85%). Nickel accounts for about 10%. That last 5% however, has remained a bit of a mystery.

A Japanese research team has been searching for that missing element for decades, and now believes that the final 5% is most likely made from silicon, reports the BBC. They presented their results at the Fall Meeting of the American Geophysical Union in San Francisco.

The Earth's solid core, which lies about 3,000 km below the surface, is thought to have a radius of about 1,200 km. Since it's so deep, it's impossible to directly test it, and find out precisely what the core is made of. (For comparison, the world's deepest mines only reach a depth of about 4 km.)

The Earth's core is mostly molten iron
Image: Soylent Green

Silicon has been a contender as the missing element in the core for a while. Researchers knew that it had to be a lighter element, and silicon has been suggested many times, because of its properties, such as how well it bonds to metals.

So instead of digging, the team from the University of Tohoku decided to create a miniature Earth — crust, mantle core, and all — in the lab. First, they created alloys of iron and nickel and mixed them with silicon, then subjected them to the huge pressures and temperatures that exist within the core — about 6,000 degrees Celsius.

These conditions matched the seismic data of the Earth's core, which is information from the seismic waves that emanate from near the centre of the Earth. This gave the team sufficient evidence that silicon was probably the missing element.

"These difficult experiments are really exciting because they can provide a window into what Earth's interior was like soon after it first formed, 4.5 billion years ago, when the core first started to separate from the rocky parts of Earth," Professor Simon Redfern, professor of mineral physics at the University of Cambridge told the BBC news: "But other workers have recently suggested that oxygen might also be important in the core."

Knowing what exactly is down there could help scientists determine the conditions that helped form the Earth.

Don't miss any update on this topic

Create a free account and access your personalized content collection with our latest publications and analyses.

Sign up for free

License and Republishing

World Economic Forum articles may be republished in accordance with the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International Public License, and in accordance with our Terms of Use.

The views expressed in this article are those of the author alone and not the World Economic Forum.

World Economic Forum logo
Global Agenda

The Agenda Weekly

A weekly update of the most important issues driving the global agenda

Subscribe today

You can unsubscribe at any time using the link in our emails. For more details, review our privacy policy.

About Us



Partners & Members

  • Sign in
  • Join Us

Language Editions

Privacy Policy & Terms of Service

© 2024 World Economic Forum