A study published yesterday, Monday, in the journal “Nature Geoscience” stated that the Earth’s core, which is a flaming ball the size of Pluto, can move freely within a liquid envelope that forms the outer core. It may have stopped rotating, and may have started moving in the opposite direction, in a conclusion that will rise. Controversy among specialists on this issue.
This “planet within Earth” is composed mainly of iron and is located 5,000 kilometers below the Earth’s surface.
The exact process of the core’s rotation is a matter of debate, because the limited information available is based on careful analysis of seismic waves generated by earthquakes as they pass through the center of the planet.
After researchers, Xiao Dong Song and Yi Yang of Peking University, analyzed seismic wave data for the last 60 years, they concluded that the rotation of the nucleus “became almost stopped in 2009, before it resumed moving in the other direction.”
“We believe that the central nucleus rotates in one direction each time relative to the Earth’s surface, similar to the motion of a seesaw,” the two specialists told AFP.
They pointed out that “the full cycle (in both directions) of the central nucleus takes about seventy years.” The last change in rotation before the one that occurred in 2009 dates back to the early seventies of the twentieth century, while the next change will be recorded in the mid-forties of the current century, thus completing the nucleus cycle, according to the two Chinese researchers.
“A very careful study.”
The two scientists point out that this rotation depends in one way or another on changes in the length of the day, which are small differences in the exact time that the Earth needs to rotate on its axis.
To date, there are few indications of the effect of this rotation on what is happening on Earth’s surface. However, the researchers appear convinced of the existence of real physical connections between all the layers that make up the Earth. “We hope that our study will motivate other researchers to design and test models that treat the Earth as an integrated dynamic system,” they say.
The study received the attention of independent experts, who, on the other hand, expressed certain reservations about it.
“It’s a very careful study, done by two excellent scientists based on a large amount of data,” John Vidal, a seismologist at the University of Southern California, told AFP, but considered that “none of the existing models interprets well all the available data.”--
Last year, John Vidal published a study stating that the inner core oscillates rapidly with a change in the direction of its rotation approximately every six years, based on seismic data from two nuclear explosions dating back to the late 1960s and early 1970s.-
This finding constitutes a turning point close to that indicated by the Chinese researchers’ study, which the American seismologist considered to be a “coincidence”.
Russian Matryoshka dolls
Another theory, which Vidal considered to be based on strong data, indicated that the inner core did not move significantly except between 2001 and 2013, before it witnessed stability since then.
The geophysicist at the Australian National University, Hurwit Calchich, pointed out that the rotation of the inner core takes between 20 and 30 years, not 70 years, as mentioned in the study of the two Chinese scientists.
He believed that “all of these computational models are most likely incorrect,” because even if they explain the available data, these data may constitute answers to other models that have not yet been studied.
He points out that the geophysical community has all the reasons “to be divided regarding this discovery, and to remain a matter of controversy.”
Calchich likens seismologists to physicians “who examine a patient’s internal organs with incomplete or limited equipment”. It is similar to trying to understand the workings of the liver through ultrasound alone.
He considers that “our concept of the Earth’s interior will remain mysterious” without a tool similar to the scanner, expecting more surprises in this field, such as the theory that the inner core hides a ball of iron smaller than it, similar to Russian Matryoshka dolls.