Scientists: The length of days on Earth increases due to the inner core

-
USC scientists have proven that Earth's inner core is slowing down relative to the planet's surface, according to new research published in the journal Nature.

The motion of the inner core has been debated by the scientific community for two decades, with some research suggesting that the inner core is rotating faster than the surface of the planet.

The new University of Southern California study provides unequivocal evidence that the inner core has begun to slow down since 2010, moving more slowly than the Earth's surface, which slightly affects the Earth's rotation in space.

However, don't expect to enjoy more hours in the day just yet, as scientists say the change may be very difficult to notice.

“When I first saw the seismograms that hinted at this change, I was puzzled,” said John Vidal, dean of earth sciences at the USC Dornsife College of Letters, Arts and Sciences. “But when we found twenty other observations pointing to the same pattern, the conclusion was inevitable.” "The inner core has slowed down for the first time in several decades. Other scientists have recently argued for similar and different models, but our latest study provides the best and most convincing analysis."

For many years, many scientists believed that the inner core rotated faster than the Earth's surface. However, the core has now slowed down and begun to move backwards.

The inner core is a solid ball of iron and nickel surrounded by an outer core of liquid iron and nickel. It is approximately the size of the moon, and the inner core is located at a depth of more than 3,000 miles (4,800 kilometers) under our feet, and therefore represents a challenge for scientists and researchers, as it cannot be visited or viewed. Scientists must use seismic waves from earthquakes to create visualizations of the movement of the inner core.

Unlike other research, Vidal and Wei Wang of the Chinese Academy of Sciences used repeated waveforms and earthquakes. Repeated earthquakes are seismic events that occur at the same location to produce identical seismograms.

In this study, scientists compiled and analyzed seismic data recorded around the South Sandwich Islands from 121 recurring earthquakes that occurred between 1991 and 2023.

They also used data from Soviet nuclear tests between 1971 and 1974, as well as repeated French and American nuclear tests from other studies of the inner core.

Vidal said that the slowdown in the speed of the inner core was caused by the swaying of the outer core of liquid iron surrounding it, which generates the Earth's magnetic field, in addition to gravitational forces from dense areas of the covering rocky mantle.

The effects of this change in the movement of the inner core of the Earth's surface can only be speculated on. Vidal explains that the retreat of the inner core may change the length of the day by fractions of a second.

Future research by USC scientists hopes to chart the path of the inner core in more detail to reveal exactly why it is shifting.