The Earth’s core is one of the most mysterious components of our planet and surprising investigations often appear.
The last one is that it seems to have slowed down and could even be rotating in the opposite direction to the surface.
This not a harbinger of the apocalypsebut it could influence the speed at which the Earth rotates, the slight changes in the length of its days and its magnetic behavior, although more studies are required to confirm this.
“We see compelling evidence that the Earth’s core has been rotating faster than the surface, but around 2009 it stopped,” says geophysicist Song Xiaodong of Peking University in China, one of the authors of the new study published on September 23. January in the magazine Nature Geoscience.
The Earth’s core is a sphere of iron and nickel with a radius of 1,221 kilometers. It is very hot; its 5,400 °C equates it to the temperature of the Sun (5,700 °C).
And it is surrounded by a thick layer of liquid metals known as the outer core.
Understanding exactly how it rotates has been the subject of debate among scientists for decades.
What does the new study say?
The Earth’s core 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. is located at more than 5,000 kilometers under our feet. What little we do know comes from measuring small differences in seismic waves generated by earthquakes and nuclear explosions.
The authors of the new study, Song Xiaodong and Yang Yi, based on these vibrations from the analysis of different earthquakes in the last six decades.
Their theory not only argues that “the inner core rotates from one side to the other like a swing”, but that this happens in cycles of seven decades, with changes in the direction of rotation every 35 years, according to what they explained to the AFP agency.
According to their findings, the last time it changed direction was in the early 1970s, and the next change would occur in the mid-2040s.
That is It would not be a new phenomenon.
The researchers said this rotation roughly coincides with changes in day lengths, which are small variations in the exact time it takes Earth to spin on its axis.
Different opinions
Until now there is not much evidence on the influence of the behavior of the nucleus on the surfacealthough researchers believe that there are physical links between all the Earth’s layers.
Yang and Song hope that their findings “will motivate researchers to build experimental models that treat the Earth as an integrated dynamic 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 center.
One of the big questions that remains is how to reconcile the slowdown described by Yang and Song with the faster 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 oscillates much faster, changing direction every six years or so.
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 models, Vidale predicts “more surprises” about the mysterious heart of our planet.
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