Scientists have now confirmed the Earth does indeed have a solid core, after over 80 years of speculation.
Danish seismologist Inge Lehmann first suggested the Earth had a solid core way back in 1936. However, this has now only just been proven by researchers from the Australia National University (ANU).
While conducting their research, associate professor Hrvoje Tkalčić and PhD scholar Than-Son Phạm examined shear waves – also known as ‘J waves’ – within the inner core of the Earth. J waves are triggered by earthquakes, travelling only through solid objects.
Tkalčić and Pham compared signals received at various locations following major earthquakes, using their findings to create a ‘fingerprint of the Earth’. The team has previously used a similar technique to measure the thickness of ice in Antarctica.
According to this research, which has been published in Science Magazine, the Earth’s core is ‘solid but soft,’ much like how I take my boiled eggs:
Earth’s inner core is thought to be solid, which means it should support shear waves. However, the small size of the inner core makes detecting shear waves very difficult.
Tkalčić and Phạm correlated different types of seismic phases to finally determine the speed of shear waves in Earth’s inner core (see the Perspective by Irving). The detection of the waves closes an 80-year quest to find them and confirms a solid, but soft, inner core.
Until Lehmann’s 1936 hypothesis, scientists believed the centre of the Earth contained a reservoir of liquid rock, enfolded by solid mantle and covered by the Earth’s crust.
These new findings will undoubtedly prove very important for researchers when understanding more about the formation of Earth.
As reported by Phys.org, Tkalčić said:
We found the inner core is indeed solid, but we also found that it’s softer than previously thought,
It turns out – if our results are correct – the inner core shares some similar elastic properties with gold and platinum. The inner core is like a time capsule, if we understand it we’ll understand how the planet was formed, and how it evolves.
The world truly is an eternally surprising place.
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