After a 20-Year Search, Scientists Have Finally Found Earth's True Innermost Core
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Loading... - Melissa Grenier
- 22 Feb 2023
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Our home planet is seeming more like a jawbreaker the more we learn about its interior.
A new analysis of Earth's innards suggests the presence of an inner core within the inner core – a dense ball of iron at the very center of our planet.
This could reveal some previously unknown details about the history of Earth's formation and evolution, suggesting a significant global event early in our planet's history.
Earth's interior structure consists of a series of concentric layers, from the crust to the core. At the very center, with a radius of about 1,227 kilometers (762 miles) is the inner core – the densest part of our planet, a solid ball mostly composed of iron and nickel, comprising less than 1 percent of Earth's volume.
This inner core is like a time capsule of Earth's history.
As the inner core grows, the solidification process releases heat and light that drives convection in the outer liquid core – the engine that powers the dynamo that converts kinetic energy into magnetic energy and maintains Earth's global magnetic field. That magnetic field is thought to keep harmful radiation out, and the atmosphere in, allowing life to thrive.
Changes in the inner core could thus trigger changes in the dynamo, which in turn could have implications for Earth's habitability over time.
But studying the inner core isn't easy. We can't just pop down there and drill into it; instead, we have to rely on seismic waves that bounce around inside the planet, changing as they encounter volumes of varying density.
Over 20 years ago, scientists identified the presence of another, even innerer core inside the inner core. They called it the innermost inner core, and other studies have supported its existence; but finding out more about it has remained difficult, partly because it's obscured by so many other layers, and partly because placing seismic stations in the right spots can be hard to do.
However, the number of global seismic monitoring stations around the globe is continuing to grow, constantly recording the imperceptible shuddering of the planet beneath our feet. And now seismologists Thanh-Son Phạm and Hrvoje Tkalčić from the Australian National University (ANU) in Australia have figured out a way to squeeze data on the innermost inner core out of those recordings. Read More…
