SPACE — Scientists in China recently made a discovery at the heart of our planet, namely that every 8.5 years, the Earth’s core vibrates on its rotation axis. The shift is likely due to a small misalignment between the Earth’s inner core and mantle, the layer beneath the Earth’s crust.
The research was published in the journal Nature Communications on December 8, 2023. According to them, starting about 2,896 km below the surface, the Earth’s core is divided into a swirling liquid outer boundary and a mostly solid inner layer. This region is partly responsible for a number of our planet’s geophysical dynamics, from the length of the day to the Earth’s magnetic field.
This helps protect humanity from the harmful rays emitted by the sun. The newly discovered tilt of the inner core ultimately causes changes in the shape and movement of the liquid core, leading to a potential shift in the Earth’s magnetic field.
To better understand how the Earth’s core works, in 2019 geophysics researchers led by Hao Ding from Wuhan University, analyzed the relative movement of the Earth’s rotational axis relative to its crust, known as polar rotation. They detected slight deviations in the pole’s motion that occur every 8.5 years, indicating the potential for a wobble of the inner core, similar to the wobble of a spinning top.
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In their latest research, Ding and his coauthors further confirmed the cycle. They measured small shifts in day length across the globe, controlled by periodic movements of the Earth’s rotational axis, and compared them with previously identified data on variations in polar motion.
Their data shows that the wobble of the Earth’s core is most likely caused by a 0.17 degree tilt between the inner core and the mantle, which contradicts previous theories of the Earth’s rotation. “It assumes that the rotation axes of the Earth’s core and mantle coincide,” Ding told Live Science via email.
The tilt is thought to indicate the northwestern hemisphere of the inner core is slightly denser than the other layers. Then, there is a difference in density between the inner and outer core of the earth.
University of California earth sciences professor John Vidale said the new research from China helped distinguish the composition between the metals in the solid inner core and the liquid outer core. Then estimate the direction and speed of the inner core wobble. “There’s nothing here that will save humanity this week, but it adds to the basic foundation of understanding our planet,” he said.
The research team ruled out atmospheric, oceanic and hydrological influences causing deviations in polar motion other than inner core wobbles. However, Vidale said, it is difficult to ensure that these sources did not play a role because many experts were needed to compile the analysis in the study.
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In the future, their findings could help other researchers understand the dynamics of the Earth’s core and the processes that can impact human life. Starting from earthquakes to changes in magnetic fields. Source: Live Science
2023-12-30 11:58:00
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