Earth’s inner core may have ‘paused’ its rotation and reversed, new study suggests
Deep in the center of the Earth is the inner core, which spans roughly 746 miles and is composed primarily of pure, solid iron, NASA explains. While we’ve long believed—and research has shown—that the inner core rotates, a new study suggests that it may have “paused” its rotation and may even have reversed.
The liquid outer core that surrounds the inner core causes Earth’s magnetic field. According to NASA, as the molten iron and nickel in the outer core move, they create electrical currents that result in a magnetic field. The outer core also allows the inner core to spin itself, Nature explains.
While scientists can’t observe the core directly, they can analyze seismic waves from earthquakes — and Cold War-era nuclear weapons tests — as they reach the core. That’s what study co-authors Yi Yang and Xiaodong Song, seismologists at Peking University in Beijing, did for their new research, published Monday in the journal Nature Geoscience.
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Based on their analysis of seismic waves caused by similar earthquakes from the 1960s, Yang and Song said they found that the rotation of the inner core appears to have “stopped” between 2009 and 2020 and may even reverse “by a small amount.”
Sounds alarming, doesn’t it? Don’t panic – this probably isn’t the first time our inner core has stalled. Instead, they believe the change is “associated with the gradual return of the inner core as part of an oscillation of around seven decades”.
According to Yang and Song, the results of their study also suggest “another upheaval or deceleration of rotation around the early 1970s.”
The seismologists said their findings — changes in how fast seismic waves traveled through the inner core — are consistent with “changes in several other geophysical observations, notably the length of the day and the magnetic field,” both areas that are affected by the movement of the inner core. , the research showed.
Even if the changes are “valid,” what Yang and Song found may not be exactly what is happening deep within our planet. John Vidale, a professor of earth sciences at the University of Southern California who was not involved in the study, noted to The Wall Street Journal “several competing ideas” about the Earth’s core.
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This includes theories that the inner core reverses its spin more often than the 70 years that Yang and Song determined, and that it stopped spinning in the early 21st century.
“No matter which model you like, there are some data that doesn’t agree with it,” Vidale told The New York Times.
Vidale recently co-authored a study that showed that the inner core changed its rotation between 1969 and 1974 and that it appears to oscillate “a few kilometers every six years.
