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07-09-2024

Earth’s inner core rotation has begun moving backwards

In these modern times, we often take the stability of our world for granted. However, an academic revelation suggests we are in the midst of a change so drastic that it feels as if the very ground beneath our feet is shifting. Well, at least the ground 3,220 miles beneath our feet, in Earth’s inner core.

Research spearheaded by Dr. John Vidale, Dean’s Professor of Earth Sciences at the University of Southern California’s Dornsife College of Letters, Arts and Sciences, has confirmed a slow deceleration of Earth’s inner core rotation to the point where it is moving backwards. This perplexing shift may have profound implications for our planet.

Earth’s inner core

Our Earth holds a secret deep within. Discovered by Danish seismologist Inge Lehmann in 1936, the earth’s inner core is a solid metal ball, somewhat akin to an inscrutable top whirling independently inside our spinning planet.

Despite its elusive nature, the inner core has drawn the interest of the scientific community for its peculiar characteristics, primarily its rotation speed and direction.

The persistent debates have finally led to the assertion that our inner core’s spin is not constant; instead, it might be slowing down.

Seismic waves

Understanding the rotation of the inner core is a bit like trying to read a book in the dark. The inner core is out of reach for direct observation or sampling.

Scientists have relied on examining the seismic waves from large earthquakes and their interaction with the core to gain insights.

“Differential rotation of the inner core was proposed as a phenomenon in the 1970s and ’80s, but it wasn’t until the ‘90s that seismological evidence was published,” said Dr. Lauren Waszek, a senior lecturer of physical sciences at James Cook University in Australia.

However, interpreting these findings has been contentious due to limitations in observing and collecting accurate data.

Earth’s core spinning slower

One hypothesis, proposed in 2023, suggested that the inner core, which had once spun faster than Earth, was now spinning slower.

At one point, the scientists reported, the core’s rotation matched Earth’s spin, and then it began to decelerate more, moving backward relative to the fluid layers around it.

This proposition has been strengthened by recent research, which not only confirms the core slowdown but also corroborates the idea that this deceleration is part of a decades-long pattern of varying speeds.

Cycle of Earth’s inner core

The new study led by Dr. Vidale, reveals that changes in rotational speed follow a 70-year cycle.

“We’ve been arguing about this for 20 years, and I think this nails it,” Vidale said. “I think we’ve ended the debate on whether the inner core moves, and what’s been its pattern for the last couple of decades.”

Despite such confidence, not everyone is convinced that the matter is settled.

The implications of the internal core slowdown and how it might affect us remain a perplexing puzzle — though some link it to Earth’s magnetic field.

Magnetic phenomenon

The interplay of Earth’s magnetic field, forces of gravity, the flow of the fluid outer core, and mantle produce variations in the core’s rotational speed.

This “push and pull” influence the solidity and positioning of our inner core.

A slower-spinning core, studies suggest, could potentially affect Earth’s magnetic field, a protective shield safeguarding the planet from deadly solar radiation. It could also fractionally shorten the length of a day.

Earth’s magnetic field and its inner core

Picture Earth as a giant magnet, its magnetic field extending from the heart of our world into the vastness of space. This mighty shield is born from a dance deep below our feet, where molten iron and nickel swirl and tumble in Earth’s outer and inner cores.

As they move, they give birth to electric currents, naming life to their very own magnetic fields. When these fields get together, they create a larger, intricate magnetic layer that envelops the Earth, reaching into the cosmos and forming what we call the magnetosphere.

Protection from cosmic rays

The magnetosphere is our world’s silent guardian, standing firm against the solar wind and cosmic radiation. Imagine a stream of charged particles, hurled our way from the Sun.

It sounds scary, right? But fear not. This stream could strip away our atmosphere if not for our shield — the magnetosphere.

Instead of causing destruction, our magnetic field reroutes these particles, eventually causing the beautiful dance of Northern and Southern Lights near the poles. Nature’s own light show!

The protection that the magnetosphere provides is like a safety blanket, keeping Earth as the perfect haven for all life.

Constantly evolving like Earth’s inner core

Earth’s magnetic field isn’t set in stone. It’s alive, experiencing changes and even pole reversals — the magnetic north and south trading places. This hasn’t happened for a few hundred thousand years, but who knows when it might occur again.

Why does this matter? Understanding these shifts and shakes is crucial for our navigation systems, and also gives us exciting clues to the geological history etched into the Earth’s rocks.

Finally, and most importantly, what impact will the changing rotation of Earth’s inner core have on our protective magnetic field?

Delving deeper into core matters

Unraveling the mysteries of the spin of our inner core — though imperceptible to us — holds significant potential.

This research offers an exciting look into how Earth’s deep interior formed and how activity across all the planet’s subsurface layers is interconnected.

For instance, seismic waves produced by earthquakes at different times reveal changes in the core rotation over the years.

Deducing from their calculations, Dr. Vidale and his team predict that the core should start accelerating again in about five to 10 years.

As interesting as that sounds, it still leaves us on the incline of this scientific roller coaster. “We need more data and improved interdisciplinary tools to investigate this further,” Dr. Waszek advises.

Towards an uncharted territory

As we plunge deeper into the enigmas of our Earth’s inner core, we unlock numerous possibilities.

The boundary where the liquid outer core envelops the solid inner core is a region where “liquid and solid meet,” as Dr. Vidale puts it, “filled with potential for activity”.

This interplay between the inner core’s rotation and the movement in the outer core helps power Earth’s magnetic field. Yet, the inner core’s exact role needs further probing.

One thing’s for sure; we stand on the precipice of a new frontier in our understanding of our Earth. As we dig deeper into the mysteries of our planet, we might just unearth a new worldview.

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