Scientists have made a discovery in the mysterious innermost core of the Earth

Earthquakes reveal the secrets

The Chinese researchers from Peking University believe they have found evidence that the rotation of the 1,300-kilometer-wide core appears to have slowed down a bit recently, and that the core may even be about to start spinning in the opposite direction than it has been doing in previous decades.

The researchers came to that conclusion by analyzing the travel time of seismic waves from various earthquakes, which have penetrated the innermost layers and out the other side over the past six decades.

According to the researchers, waves revealed that the Earth’s inner core was rotating slightly faster than the Earth’s mantle and surface until the year 2009. After that, it looks like the core slowed down a bit, keeping up with the rotation of the mantle and the rest of the Earth’s surface, and now think they therefore that it may be heading in the opposite direction.

Researchers: “It’s not the first time”

According to the research group, it is not the first time that the iron man takes a short break.

In the early 1970s, they also observed a strange change in seismic waves, suggesting that the slowdown may be part of a pattern in which the inner core—about every seven decades—begins to twist in the opposite direction.

JOIN THE JOURNEY: Earth’s interior hides a cake of extremes

Many different theories

The rotation in the Earth’s innermost core is, to say the least, a hot scientific topic and it is far from the first time that researchers present new theories about the movement of the red-hot iron mass. In 2004, researchers drew on Columbia University for example, the conclusion that the core rotated faster than the surface of the earth itself. In 2011, scientists then discovered that it twists much slower than we previously thought.

And in 2021, geophysicists considered at University of Southern California that the inner core moved in a six-year cycle in one direction and a six-year cycle in the other direction.

“We know more about the sun”

The new 70-year theory also faces skepticism from several quarters. But it is not so strange, because the theories are many and different. This is explained by Chris Finlay, professor at DTU Space in the department of geomagnetism and geospace.

He has not himself participated in the new study, but researchers in the Earth’s magnetic field and has himself previously used data from satellites to investigate the Earth’s interior.

“The innermost core is the part of the Earth we know the least about – we actually know more about the Sun than we do about what goes on deep inside the Earth. The reason is that there are 5,000 kilometers of rock and liquid metal between us and it, and therefore, it is also extremely difficult to investigate,” he explains.

Like diagnosing without direct samples

The long and impassable distance means that we are dependent on indirect observations – such as seismic waves or changes in the Earth’s magnetic field – a bit like examining a disease inside the body without taking any direct samples of it. Therefore, he does not believe that the new study should be perceived as a final conclusion for what is happening in there.

“This study is part of a process in which we try to learn more about this hidden place on our planet. But there will be much more to this story – it is not the end,” he explains.

The question then becomes why should we be at all interested in what is happening in a red-hot chamber several thousand kilometers below our feet? We should, according to the professor, because it can tell us something about what happens to our natural shield against radiation from space – the Earth’s magnetic field.

“It is the movements of the liquid part of the core, which is up against the inner, solid core, that generates our magnetic field. The liquid part is like a hot sea of ​​metal, where the turbulent movements pull with the inner core. The two parts of the core is a kind of companion and therefore the rotation in the innermost core and when associated with what happens with our magnetic field,” he explains.