The rotation of the Earth’s inner core has slowed down

Deep in the heart of our planet something amazing is happening. Scientists have discovered that the Earth’s inner core, a solid sphere of iron and nickel with a radius of about 1,220 kilometers, is slowing down. That’s according to a new study led by a team from the University of Southern California (USC), which provides evidence that the inner core began to slow down around 2010, moving slower than the Earth’s surface. It’s official. The core rotates slower than the surface of the planet.

Irrefutable evidence

The Earth’s inner core is a region that remains one of the least understood but most intriguing parts of our planet. plays a vital role both in the configuration of the Earth’s magnetic field (our planet’s magnetic field is created, for example, by the movement of an outer core of liquid iron surrounding a solid inner core), and in tectonic activity or the overall dynamics of our planet.

“When I first saw the seismograms hinting at this change, I was puzzled,” explained USC scientist John Vidale. “But when we discovered two dozen more observations pointing to the same pattern, the result was inevitable. The inner core slowed for the first time in decades. “Other scientists have recently advocated similar and different models, but our latest study provides the most compelling solution yet.”

Is it slowing down? What does it mean?

The discovery raises important questions about planetary mechanics and could affect both the stability of Earth’s magnetic field and the length of our days. This change in the Earth’s inner core could lead to longer days. although for mere mortals this will not be something tangible, since the consequences will be in additional fractions of a second (on the order of a thousandth of a second). “It’s very hard to notice that for a millisecond he’s almost lost in the noise of the churning oceans and the atmosphere,” Vidale says.

By examining recent decades of seismic data recorded around the South Sandwich Islands from 121 repeat earthquakes that occurred between 1991 and 2023, as well as data from twin Soviet nuclear tests between 1971 and 1974 and other studies of the inner core. As for repeated earthquakes, they are very interesting because originate from the same location and create identical patterns of seismic waves (seismograms), providing a coherent framework for studying the Earth’s interior.

Scientists discovered that the inner core began to slow down around 2010, and now the following is happening. moves backwards something that subtly influences the Earth’s rotation in space. But the reality is: Compared to the speed of previous decades, the inner core is slowing down; It turns over and moves away relative to the surface of the planet.

And why is it slowing down?

The exact reason for the inner core’s slowdown is still unclear, but researchers They put forward two hypotheses: 1) that the turbulent motion of the outer core of liquid iron, responsible for creating the Earth’s magnetic field, exerts a drag force on the inner core that would slow down its rotation; or 2) that gravitational interactions with denser regions of mantle rocks above the outer core may pull on the inner core, further helping to slow it down.

What will happen now? The team now wants to trace the trajectory of the inner core in more detail to figure out exactly why it is changing and determine whether any of these hypotheses are correct, since the rotation of the inner core is an important factor in the process geodynamo is generated by the Earth’s magnetic field, and any changes could potentially affect the strength and stability of the magnetic field that protects the planet from harmful solar radiation. Let’s remember that a stable magnetic field is necessary to maintain the atmosphere and support life on Earth. At this point, the consequences this modification will have are almost impossible to predict, but this discovery opens a new line of research, offering a deeper understanding of the Earth’s complex inner core.

“The dance of the inner core may be even more animated than we know so far,” Vidale concludes.

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