Study indicating that the Earth’s core has slowed down


The latest is that it appears to have slowed down and may even rotate in the opposite direction from the surface.

This isn’t a harbinger of the apocalypse, but it could affect Earth’s rotational speed, slight changes in the length of its days and its magnetic behavior, although more studies are needed to confirm this.

“We see compelling evidence that the Earth’s core rotated faster than the surface, but around 2009 it stopped spinning,” says geophysicist Song Xiaodong of Peking University in China, one of the authors of the new study published today in the journal Nature. Geosciences.

The core of the Earth is a sphere of iron and nickel with a radius of 1,221 kilometers. It’s very hot; its 5,400 °C is equivalent to the temperature of the Sun (5,700 °C).

And it’s surrounded by a thick layer of liquid metals known as the outer core.

Understanding exactly how it rotates has been a matter of debate among scientists for decades.

What does the new study say?

The core of the Earth has been described as a kind of “planet within a planet”. Because it floats in a thick layer of liquid, it can rotate independently.

It is difficult to study the nucleus precisely. It is more than 5,000 kilometers under our feet. What little we know comes from measuring small differences in the seismic waves generated by earthquakes and nuclear explosions.

You cannot directly analyze what is happening in the core of the Earth.

The authors of the new study, Song Xiaodong and Yang Yi, build these vibrations from the analysis of several earthquakes over the past six decades.

Their theory not only holds that “the inner core rotates from side to side like a seesaw,” but that it does so in cycles of seven decades, with rotational direction changing every 35 years, they explained to the Agency. AFP extension.

According to their findings, the last time it changed direction was in the early 1970s, and the next change occurred in the mid-1940s.

In other words, it would not be a new phenomenon.

The researchers said this rotation roughly coincides with changes in day length, which are small variations in the exact time it takes for the Earth to rotate on its axis.

Different opinions

So far there is not much evidence on the influence of the behavior of the core on the surface, although the researchers believe that there are physical connections between all layers of the Earth.

Yang and Song hope their findings “will motivate researchers to build experimental models that treat the Earth as a dynamically integrated system,” they say.

Other experts, however, are wary of the new study, citing other theories and warning of the many ongoing mysteries of the Earth’s core.

Scientists rely on the vibrations of earthquakes to study the Earth’s core.

One of the big questions that remains is how to reconcile the slowdown described by Yang and Song with the more rapid changes reported in other studies.

John Vidale, a seismologist at the University of Southern California, published research last year indicating that the Earth’s core is swinging much faster, changing direction about every six years.

In his case, it was based on seismic waves caused by two nuclear explosions in the 1970s.

Hrvoje Tkalcic, a geophysicist at the Australian National University, has published other research suggesting that the rotation cycles of the Earth’s core last between 20 or 30 years instead of 70.

Given the discrepancy in the models, Vidale predicts “more surprises” at our planet’s mysterious heart.

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