What Exactly is Happening at the Earth’s Core?

What Exactly is Happening at the Earth’s Core?

There was a bit of a buzz on social media recently that the Earth’s inner core was reversing direction.

The rotation of Earth’s inner core may have paused and it could even go into reverse, new research suggests.

The Earth is formed of the crust, the mantle and the inner and outer cores. The solid inner core is situated about 3,200 miles below the Earth’s crust and is separated from the semi-solid mantle by the liquid outer core, which allows the inner core to rotate at a different speed from the rotation of the Earth itself.

With a radius of almost 2,200 miles, Earth’s core is about the size of Mars. It consists mostly of iron and nickel, and contains about about one-third of Earth’s mass.

In research published in the journal Nature Geoscience on Monday, Yi Yang, associate research scientist at Peking University, and Xiaodong Song, Peking University chair professor, studied seismic waves from earthquakes that have passed through the Earth’s inner core along similar paths since the 1960s to infer how fast the inner core is spinning.

However, the inner core isn’t reversing direction. It’s simply reverting back to a slower spin speed, which research suggests is part of a 70-year oscillation cycle. The core’s behavior can impact the Earth’s magnetosphere and length of day.

The behavior of the core may be linked to minute changes in the length of a day, though the precise details are a matter of debate. The length of a day has been growing by milliseconds over centuries because of other forces, including the moon’s pull on Earth. But ultraprecise atomic clocks have measured mysterious fluctuations.

These variations may line up with changes in the core’s rotation, Song and colleagues argue. The new paper finds that, when they remove predictable fluctuations in the length of a day due to the moon’s tidal forces, there are changes that appear to track with the 70-year oscillations in the inner core’s rotation.

Paul Richards, a seismologist at the Lamont-Doherty Earth Observatory at Columbia University, worked with Song to put forward the initial evidence that the core was spinning faster than the rest of the planet.

“Most of us assumed that the inner core rotated at a steady rate that was slightly different from the Earth,” Richards said. “The evidence accumulates, and this paper shows that the evidence for [faster] rotation is strong before about 2009, and basically dies off in subsequent years.”

The Earth’s magnetosphere protects the planet from solar radiation and is a significant reason why life can thrive on Earth. The spin of the inner core is important to the generation of the global magnetic field.

The inner core is about 70% of the moon’s radius and is believed to be primarily made of iron. It is believed to be solid.

The outer core is liquid. It is made of iron and nickel and is very hot. The temperature of the core is believed to be 9,800 degrees Fahrenheit.

We know a little more about the Earth’s mantle. It makes up 84% of the Earth’s volume. It is primarily solid but acts sort of like caramel, according to NASA.

The paper states that as the outer core cools, it fuses with the inner core. During this transition, heat is released, generating the Earth’s magnetic field. This, plus the gravity exhibited by the mantle, causes the inner core to spin.

More on this research can be found here for those of you who are interested.

Interestingly, in 2019, I reported that the Earth’s magnetic field was moving erratically and the location of the magnetic North Pole. Another Nature Geoscience study on the core’s behavior may explain this shift.

It is this exact position that is affected by the movements of the planet’s core. And, as this position changes, so too does the North Pole’s location. Scientists say that the current direction of the pole’s movement is caused by a “blip in the pattern” of the flow inside of the Earth’s interior. This blip, they believe, occurred somewhere between 1970 and 1999.

Because the blip happened, the Canadian field of the North Pole itself has become elongated, losing its influence over the Earth’s magnetosphere. This has caused the North Pole’s location to move quickly towards a magnetic field located under Siberia. The researchers say that our northern magnetic pole is controlled by these two patches, or blobs.

And it’s these blobs that have kept the North Pole’s location in a constant state of tug of war. But, because the Canadian portion of this field has elongated and become weaker, the pole’s location has quickly found itself drawn to the field in Siberia.

The study on the pole shift can be found here.

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