Earth’s renegade inner core may have ‘paused’ and reversed, scientists say

Deep earth can slow its rolling.

Earth’s solid iron inner core appears to be spinning at a slower rate than the planet, according to a new study – but no worries, scientists think it’s been changing speed and direction for eons.

The 9,400-degree inner core – discovered in 1936 by studying waves from earthquakes – has a radius of about 746 miles and is about 70% the size of the Moon, according to NASA.

The inner core sits beneath the planet’s inner core of molten iron and nickel – and the churning relationship between the two generates currents that maintain Earth’s magnetic field, scientists say.

The “planet within a planet” has been shown to move at its own pace; speed up, slow down and spin, and a new study suggests the inner core may be operating on a 70-year cycle.

A new study suggests that the Earth’s inner core changes speed and direction over a seven-decade cycle.
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An analysis of seismic waves generated by US nuclear tests in 1969 and 1971 revealed that the inner core rotated more slowly than Earth, according to the scientific journal Nature.

After 1971, the inner core began to accelerate, spinning faster than the planet’s mantle. But around 2009, it had apparently synchronized with the rest of the planet before slowing down and possibly reversing – spinning west instead of east, the direction of the planet’s rotation.

Its recent “pause” and possible “seven-decade oscillation” were discovered by Yi Yang and Xiaodong Song, seismologists at Peking University in Beijing, who reported their findings in Nature Geoscience on Monday.

The east-west rotation cycle is expected to restart around 2040, according to the study.

Song was one of the first scientists to suggest that Earth’s inner core rotates faster than its crust, according to The Washington Post.

“The inner core is Earth’s deepest layer, and its relative rotation is one of the most intriguing and difficult problems in deep Earth science,” Song told the outlet.

The researchers said the core cycle was linked to changes in day length – which mysteriously lengthened by longer and longer microseconds – and the planet’s magnetic field.

A “long history of continuous recording of seismic data is essential for monitoring the motion of the planet’s core,” Yang and Song said.

The study has not been universally publicized in the scientific community.

Lianxing Wen, a seismologist at Stony Brook University, told the outlet he doesn’t believe the core rotates independently and said changes to its surface over time are more likely to produce different seismic data.

“This study misinterprets seismic signals that are caused by episodic changes in the surface of the Earth’s inner core,” Wen reportedly said. He also said the idea that he was slowing down and changing direction “provides an inconsistent explanation for the seismic data even though we assume it to be true.”

University of Southern California seismologist John Vidale would favor a shorter six-year oscillation pattern of the inner core.

“No matter which model you like, some data doesn’t agree,” Vidale told The New York Times, who noted that some scientists believe the inner core is just wobbly.

“Due to its inaccessibility, this abyssal realm may forever escape explanation. It is certainly possible that we will never discover it,” Vidale said, adding that he was optimistic that consensus could be reached.

Further research to unravel the mysteries of the core depends on the waves created by earthquakes and nuclear explosions, making continued research unpredictable.

The inner core is “a planet within a planet, so how it moves is obviously very important,” Song told The Times.

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