A duo of Chinese scientists shocked with research that showed that around 2009, the rotation of the Earth’s inner core, relative to the surface, stopped and now passively rides with the rotation of the entire planet before starting to rotate in a different rhythm (again, relative to the surface). Before you start jumping out of windows, this is supposed to happen all the time throughout history, roughly every 70 years. So it’s nothing. Despite the fact that other experts consider the Chinese research very controversial.
The inner core, i.e. the center of our planet and its surroundings, is still a rather mysterious place. It is probably a mass of superionic iron alloy, i.e. a more or less solid material, the temperature of which apparently reaches approximately 5,430 °C. The radius of the inner core should be about 1,220 kilometers, which corresponds to about 20 percent of the radius of the Earth or about 70 percent of the radius of the Moon. According to the new study, the inner core should have stopped (relative to the Earth’s surface) and its rotation is switching to a different rhythm.
Xiaodong Song. Kredit: Peking University.
If someone had crazy scenes from the movie 2012, which rode on an embarrassing wave of fabrications about the Mayan calendar, flashed through their minds, then of course it’s nothing like that. If the pair of Chinese geologists are right, which many other experts doubt, then they calculate that such changes in the rotation of the inner core occur in a cycle of about 70 years. As older readers will recall, no planetary apocalypses have occurred in millions of years.
In their controversial study, Yi Yang and Xiaodong Song concluded that the inner core of the Earth stopped rotating, relative to the surface of the planet, around 2009. It sounds strange, but if our ideas about the interior of the planet are correct, the inner core is a sphere of solid of material that floats in the liquid outer core. In such a system, the rotation of the inner core need not be tightly coupled to the rest of the planet.
Logos. Credit: Peking University.
Chinese researchers have analyzed seismic waves from various earthquakes that have passed through the Earth’s inner core since the 1960s. Their analyzes show that something significant changed around 2009. According to them, the inner core of the Earth took a break in its own rotation, and now passively “rides” with the rotation of the entire planet. At the same time, they believe that when the inner core starts rotating again, it will be in a different rhythm than before. Again, this is an apparent rotation relative to the surface of the planet.
According to scientists, such a change last occurred in the early seventies. They believe they have found evidence for this. According to them, the change in the rotation of the inner core should be related to other changes, for example the planetary magnetic field or the length of the day on Earth. As for the mechanisms that could drive this cycle, there are said to be several fundamental forces that compete with each other. The magnetic field generated by the Earth’s outer core could speed up the rotation of the inner core, while the massive gravity of the Earth’s mantle could slow it down.
The research was published by the journal Nature Geoscience with a very decent impact factor. Nevertheless, other experts in the world look rather skeptical or even dismissive. As geophysicist Hrvoje Tkalcic from the Australian National University told AFP, these are controversial mathematical models that are probably wrong. The geophysical community seems to be divided on this issue and it will be a controversial issue for the foreseeable future.
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Nature Geoscience online 23. 1. 2023.
