Earth's core has stopped spinning and might reverse direction: Study
The Earth's inner core rotation has 'paused,' claims new research. Earthquake data suggests the inner core stopped rotating faster than the rest of the planet in 2009. Now, the direction of the inner core's rotation may be reversing, which could be a part of a 70-year-long cycle that might influence the length of Earth's days and the magnetic field, but that's not certain.
Why does this story matter?
The heart of the Earth or the core is particularly difficult to study. But what we do know is that the core plays a role in processes that make our planet habitable, such as the generation of Earth's protective magnetic field, which blocks out the harmful radiation from reaching the surface. The latest research has raised some questions regarding the future of life on Earth.
The rotation of Earth's core affects the surface environment
The study suggests that Earth's core pauses and reverses direction on a periodic cycle lasting about 60-70 years. These findings could help explain the mysteries of climate and geological phenomena that take place during similar timelines. While the rotation of the core affects Earth's surface environment, scientists think this periodic spin switch is normal and does not pose risks to life.
Earth's inner core is about 75% of the Moon's size
Earth's inner core was first discovered in 1936 after studying how seismic waves from earthquakes traverse through the planet. The core, which is about 7,000 kilometers wide, consists of a solid center made mostly of iron and has an outer shell of liquid iron and other elements. The inner core is about 75% the size of the Moon.
The inner core spins at its own pace
As iron from the outer core crystallizes on the inner core's surface, there is a change in the density of the outer liquid, which ultimately helps maintain Earth's magnetic field. What the liquid outer core does is it disengages the 2,400-kilometer-wide inner core from the rest of the planet, so that the inner core can spin at its own pace.
The study was based on earthquakes between 1996 and 2021
The new study reveals the inner core has stopped its spin, with respect to the mantle. Researchers studied earthquakes mostly between 1995 and 2021 and found that the inner core's rotation stopped around 2009. Several points across the globe were monitored, which led to the confirmation that it was a planet-wide phenomenon and not just a local change on the inner core's surface.
Changes in Earth's core could influence the length of day
The data also suggests that the inner core might even be in the process of reversing the direction of its spin. If that's the case, then there might be changes in the magnetic and gravitational forces governing the inner core's rotation. Such changes in the core could result in an increase or decrease in the length of a day on Earth.
Gravitational coupling between inner core and mantle may be worrying
"The gravitational coupling between the inner core and the mantle may cause deformation at the Earth's surface, which would affect the sea level," said Yi Yang and Xiaodong Song, researchers of the study, to Motherboard. "The changes of the sea level and the Earth's rotation may affect the global atmosphere circulation and temperature. The resonance of different systems may also amplify the mutual interactions."
Scientists expect the core to rotate westward in coming years
According to Yang and Song, the next steps are "to build quantitative models of the physical mechanisms on the multi-decadal oscillation system" and "to monitor how the rotation changes in the future." "We'd expect it to rotate westwards relative to the surface of the Earth in the coming years and decades," noted the two seismologists at Peking University in Beijing.
