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Scientists studying Earth’s core have come up with a shocking estimate

Published Aug 26th, 2020 12:16AM EDT
earth core
Image: Reid Wiseman/NASA

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  • Scientists studying the age of Earth’s core have found that it’s likely much younger than some estimates suggested.
  • Experimenting with iron under extreme conditions allowed scientists to better grasp the forces that shaped the inner and outer core. 
  • Based on the data, the team believes the core to be as young as 1 billion years.

We don’t see it as we go about our day-to-day lives, but Earth’s core is always at work to keep us alive and comfortable on our home planet. The core is responsible for our planet’s magnetic field which protects us from some of the dangers of space, redirecting charged particles from the Sun and protecting our atmosphere. It’s an incredibly important feature of our planet, so it makes sense that researchers would like to know how old it is.

In a new paper published in the American Physical Society’s Physical Review Letters, researchers explain that, after experimenting with recreating the conditions of the core for years, they believe Earth’s core is quite a bit younger than previously thought. They now say that the core is likely somewhere between 1 billion and 1.3 billion years old.

Earth’s core is made mostly of iron. That iron is under intense pressure deep within the Earth, and the core is split into two regions: the inner core and outer core. It’s the outer core, which is fluid, that scientists believe is responsible for much of our planet’s geomagnetism.

So, what do scientists do when they need to test iron under extreme pressure? They heat it up to extreme temperatures using a laser and then slam it between two diamond anvils. It sounds like a lot of fun, but it took years before the experiments returned enough data to make an educated guess about our planet’s guts.

“We encountered many problems and failed several times, which made us frustrated, and we almost gave up,” Youjun Zhang, co-author of the study, said in a statement. “With the constructive comments and encouragement by professor Jung-Fu Lin, we finally worked it out after several test runs.”

What the team eventually found was that the conductivity of the material was significantly less than previous estimates. This suggests that the “geodynamo” — the flow of the outer core — is made possible by a combination of thermal convection and compositional convection. This is important because it gives the researchers data on how long it may have taken the inner core to solidify.

Based on all the data they have at this point, the researchers are placing their estimate on the extreme lower end of the spectrum (1 billion to 1.3 billion years), whereas past estimates have suggested the core may be as old as over 4 billion years. Understanding the forces that formed our planet and are allowing us to maintain an existence here are obviously very important and could help us to better grasp how life could be possible on other worlds.

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