The true age of Earth’s core has been discovered – and it’s younger than previously thought

Scientists have recreated the hellish conditions at the heart of our planet in a laboratory – and now believe the solid core of Earth is about a billion years old, much younger than previously thought.

The researchers measured the conductivity of iron – the material that forms the Earth’s core – under core-like conditions, with pressure over a million atmospheres and temperatures as high as the sun’s surface.

They achieved these conditions by pressing laser-heated iron samples between two diamond anvils.

Researchers at the University of Texas at Austin now believe that the planet’s solid inner core formed between a billion and 1.3 billion years ago.

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The discovery could help scientists understand the origin of our planet’s geodynamics – the mechanism that sustains Earth’s magnetic field, keeps compasses pointed north, and helps protect life from harmful cosmic rays.

Professor Jung-Fu Lin said, “People are really curious and excited about the origin of geodynamo, the strength of the magnetic field, because they all contribute to the habitability of a planet.”

The research was published in the journal Physical Review Letters.

The core of our planet is made of iron, with a solid inner core and a liquid outer core. But the researchers struggled to come up with a theory of when the solid core formed, without requiring unrealistic temperatures to maintain Earth’s geodynamics.

The new research resolves this paradox by finding a solution that keeps the core temperature within realistic parameters.

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“We encountered a lot of problems and failed many times, which frustrated us, and we almost gave up,” said article co-author Youjun Zhang, associate professor at Sichuan University in China. . “We finally fixed it after several tries.”

Lin said that with this improved information about conductivity and heat transfer over time, researchers could make a more accurate estimate of the age of the inner core.

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“Once you know how much of this heat flows from the outer core to the lower mantle, you can actually think about when the Earth has cooled enough that the inner core starts to crystallize,” says- he.

This revised age of the inner core could correlate with a peak in the strength of the Earth’s magnetic field as recorded by the arrangement of magnetic materials in the rocks that formed around this time.

Evidence suggests that the formation of the inner core was a critical part of creating today’s robust magnetic fields.