A behemoth may have started to move against us from far below our feet.
A hot iron ball the size of Pluto that makes up Earth’s inner core has ceased rotating in the same direction as the rest of the globe and may even be doing so in the opposite direction, according to research published on Monday.
This “planet within the globe” lies around 5,000 km (3,100 miles) below the surface of the planet we live on and can spin freely because it floats in the liquid metal outer core.
The precise mechanism by which the inner core spins has been a subject of controversy among scientists, and the most recent research is anticipated to be contentious.
The minor changes in seismic waves that are produced by earthquakes or occasionally nuclear explosions as they pass through the center of the Earth are what allow us to learn what little there is about the inner core.
In a recent study, published in the journal Nature Geoscience, seismic waves from recurrent earthquakes over the previous 60 years were analyzed in an effort to follow the inner core’s motions.
The inner core’s rotation “came to nearly a standstill in 2009 and then turned in the other direction,” according to research authors Xiaodong Song and Yi Yang of China’s Peking University.
According to them, the inner core swings back and forth in relation to the Earth’s surface like a pendulum.
“One cycle of the swing is nearly seven decades”, indicating it switches direction roughly every 35 years, they noted.
They claimed that it had previously reversed course in the early 1970s and anticipated the next turn would occur in the middle of the 2040s.
The researchers stated this rotation closely lines up with fluctuations in what is termed the “length of day” — minor differences in the exact time it takes Earth to circle on its axis.
Meet me halfway
There isn’t much evidence to suggest that what happens inside the inner core affects us surface dwellers very much right now.
But the scientists asserted that they thought all of Earth’s layers, from its inner core to its surface, had physical connections.
We hope that our work may inspire some scientists to develop and test models that see the entire Earth as an interconnected dynamic system, the authors said.
Experts who were not involved in the study voiced skepticism about its conclusions, citing a number of other ideas and cautioning that there are still many unanswered questions regarding the Earth’s center.
Seismologist John Vidale of the University of Southern California commented, “This is a really meticulous research by outstanding scientists putting in a lot of data.”
But, he continued, “(none) of the models, in my judgment, explain all the data particularly well.
According to studies released by Vidale last year, the inner core oscillates far more fast, changing its orientation roughly every six years. Seismic waves from two nuclear explosions in the late 1960s and early 1970s served as the basis for his research.
According to Monday’s findings, the inner core last shifted direction around that time, which Vidale described as “kind of a coincidence.”
Another idea, which, according to Vidale, has some solid evidence, holds that the inner core only considerably migrated between 2001 and 2013 and then remained in place after that.
In contrast to the 70 years that the most recent study suggested, geophysicist Hrvoje Tkalcic of the Australian National University has released research that suggests the inner core cycle occurs every 20 to 30 years.
Because they explain the observed data but are not necessary for understanding the data, Tkalcic said that all of these mathematical models are most likely erroneous.
The geophysical community will be split by this discovery, and the subject will continue to be debatable.
Seismologists, in his words, “examine the inside organs of patients’ bodies with subpar or restricted technology,” just like doctors do.
He noted that since we don’t have a CT scan, “our vision of the inside Earth is still fuzzy,” and that there would be more surprises in store.
That could cover more information on the hypothesis that the inner core may have yet another iron ball inside of it, similar to a Russian doll.
Vidale declared, “Something’s occurring, and I think we’re going to figure it out.”
But it may take ten years.