Researchers have discovered that Earth's "solid" inner core is actually a bit soft. The scientific world believed that Earth's inner core was a solid ball of compressed iron alloy which a liquid outer core covered for more than half a century.

However, according to a recent study published in the journal Physics of the Earth and Planetary Interiors on Sept. 20, the planetary ball's hardness varies from hard to semisoft to liquid metal.

Jessica Irving, a seismologist at the University of Bristol in England, who was not part of the study, told Live Science: "The more that we look at it, the more we realize it's not one boring blob of iron. We're finding a whole new hidden world."

In some respects, the deep core of the Earth is as unknown today as it was when Jules Verne wrote his fantastic "Journey to the Center of the Earth" in 1864.

Earth
Pixabay

Despite the fact that scientists have known since the 1950s that the globe isn't flat like Verne projected, the planet's interior remains undiscovered; the huge heat and pressure are just too high for any human or human-made probe to journey there.

"Unless something awful happens to our planet, we will never have a direct observation of Earth's core," Irving said.

Geophysicists instead rely on shock waves produced by earthquakes. Scientists can recreate an image of the planet's inner workings by monitoring these huge vibrations, which Irving compares to a CT scan of a human.

Straight-line compressional waves and undulating shear waves are the two basic types of these waves. As it passes through the earth, each wave can accelerate, slow down, or bounce off of various media.

The Study

The new research began as a case of mismatched data for Rhett Butler, a geophysicist at the Hawai'i Institute of Geophysics and Planetology.

Butler was looking into how seismic waves which large earthquakes created in five different places journey through Earth's core to the same opposite part of the globe.

But something wasn't quite right: the quakes' shear waves, which should have gone through a solid ball of metal, were deflected in certain places.

The numbers shocked Butler. He knew the seismic wave math was right, which could only imply one thing: the structure was incorrect. As a result, Butler and his co-author had to reconsider their original claim that Earth's inner core was solid all the way through.

They realized that the waves they saw occurred if the core included pockets of liquid and "mushy," semisolid iron at its surface, rather than being a solid ball.

Earth's Magnetic Field

According to Butler, the variety in iron consistencies was particularly noticeable.

He said: "We've seen evidence that not only is it not soft everywhere; it's really hard in some places. It's got hard surfaces right up against melted or mushy iron. So we're seeing a lot of detail within the inner core that we didn't see before."

This study has the potential to transform scientist's understanding scientist of the Earth's magnetic field. According to research published in the journal Science Advances in 2019, our planet's magnetic field is driven by the flowing liquid outer core, while the inner core helps to modulate it.

According to NASA study, some planets, such as Mars, have a liquid core but lack both an inner core and a magnetic field. As a result, Butler and Irving think that a better knowledge of the inner core will aid scientists in better comprehending the link between the inside of a planet and its magnetic activity.

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