Here’s the reason why the Earth’s core is solid despite the high temperature and pressure.

If you were once a geography student, then you pretty well know the layers of the Earth; if not, that’s why we’re here to let you know. The land you stand upon is the crust (both continental and oceanic) that surrounds a mantle, then the cores — a liquid outer core and a solid inner iron core; that’s ridiculously hot nonetheless. You might wonder at such insane temperature and pressure, why in the Earth in the bizarre nature of science is the inner core of the Earth solid for all purpose. Its a mystery that has puzzled scientists for generations. How is that even possible?


Related media: The Mystery Of The Earth’s Core Explained


At The Iron Heart Of The Earth

Yes, at the very center of our planet, is a Pluto-sized orb of solid iron; even though it’s almost the temperature as the surface of the sun, its still a solid iron core. A team of Swedish scientists think they know. But before we get to their nitty-gritty science, let’s take a crash course of atomic structures.

The atomic structure of any solid block of iron are arranged in a crystal structure. Those structures look differently depending on it temperature and pressure. At normal atmospheric temperature and pressure here on Earth, iron takes a form known as a body-centered cubic (BCC) phase — that’s the classic cubic shape with eight corners and a center. But at extreme temperature and pressure, iron morphs into a hexagonal close-packed (HCP) phase instead, which has each point surrounded by 12 other points.

The pressure at the core of the Earth is ridiculously hot, its extremely high as 3.5 million times higher than the pressure you experience up here on the surface. You might expect that at such pressure the iron crystals would morph into a hexagonal formation there; and so did scientists. Spoiler alert: No!


Let’s Get Inside The Core

Image: Shutterstock / iStock / Getty Images Plus

In a 2017 study published in Nature from Kungliga Tekniska Högskolan (KTH) Royal Institute of Technology in Stockholm, Sweden, scientists made a revolutionary discovery about the nature of the Earth’s core. Their find? Surprising! The scientists with the aid of a supercomputer, analyzed a large amount of data collected over a period of three  years prior, at the Livermore Lawrence National Laboratory in California. Surprisingly, they found that the core is in fact in a cubic structure, due to the same extreme temperature and pressure they previously thought was impossible.

At normal temperature and pressure, the cubic structure is unstable, and the atomic formation easily morph into a liquid state. But in the extreme conditions at the core, the atoms more around ever so rapidly that they get ever closer together that makes it impossible to flow. In order words, it like shuffling a deck of cards, each card changes it’s position in the deck, but the deck maintains it original form.


Root Rock Iron Core

“The sliding of these planes is a bit like shuffling a deck of cards,” says co-author Anatoly Belonoshko as he explains. “Even though the cards are put in different positions, the deck is still a deck. Likewise, the BCC iron retains its cubic structure.”

This is why the Earth’s core is “root rock solid.” It also explains why seismic waves (the ones responsible for earthquakes) travel faster between the poles than through the equator. The structure of the atoms adds more texture to the iron. This gives the core a preferred direction; and could help us make predictions about the planet and what might happen on it in the future.


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Written by: Nana Kwadwo, Fri, May 24, 2019.

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