> Earth’s inner core’s spin has slowed and “paused.”

> Scientists believe this happens roughly every seven decades as the core will then start spinning a different direction.

> A new study says there’s a direct connection between the inner core’s spin and life on Earth’s surface.

Earth’s inner core stopped spinning. But don’t fret, it appears this happens from time to time, say every seven decades or so.

A new study published in Nature Geoscience by geophysicists Yi Yang and Xiadong Song of Peking University in Beijing explored the nature of movement of Earth’s inner core, largely made up of iron and molten liquids. They found the inner core’s movement recently reduced enough they consider it “paused,” all part of what “seems to be associated with a gradual turning back of the inner core as a part of an approximately seven-decade oscillation.”

The last turning point was in the early 1970s.

Our understanding of Earth’s inner core doesn’t have a strong history. Ancient days, of course, had folks believing in a hollow core. Then came the understanding of iron and a molten mixture making up Earth’s middle, coupled with the theory of spinning happening separate from the rest of Earth. Song confirmed the spinning theory in 1996.


We don’t quite know the speed of spinning, but it appears that may be because the inner core remains in a constant state of flux and switches directions roughly every seven decades thanks to electromagnetic imbalances and gravitational forces.

The new study further tracked seismic waves through the core to see how they played out on the other side of Earth. “This globally consistent pattern suggests that inner-core rotation has recently paused,” the study says.

With the spin changing throughout the decades, the authors believe there’s an interplay between the spinning of the core and Earth’s mantle, and not just a spinning core for spinning’s sake.

“This multidecadal periodicity coincides with changes in several other geophysical observations especially the length of day and magnetic field,” the authors write. “These observations provide evidence for dynamic interactions between the Earth’s layers, from the deepest interior to the surface, potentially due to gravitational coupling, and the exchange of angular momentum from the core and mantle to the surface.”

Source: Popular Mechanics