Sign up for CNN’s Wonder Theory science newsletter. Explore the universe with news of amazing discoveries, scientific developments and more.
Pitch rotation New research suggests the inner core may have stopped and could be reversing.
The Earth is made up of the crust, mantle, and inner and outer cores. Solid The inner core lies about 3,200 miles below Earth’s crust and is separated from the semi-solid mantle by a liquid outer core, which allows the inner core to spin at a different speed than the Earth itself.
With a radius of about 2,200 miles, Earth’s core is about the size of Mars. It is composed primarily of iron and nickel and contains about a third of Earth’s mass.
In a paper published in the journal Natural Earth Sciences on Monday, Yi Yang, a research assistant at Peking University, and Xiaodong Song, an associate professor at Peking University, have studied seismic waves from earthquakes that have traveled through the Earth’s inner core in similar ways ever since. 60s to infer how fast the inner core is spinning. .
They said what they found was unexpected. Since 2009, seismic surveys have been conducted previously changed over time, Show a slight difference. They said that this indicates that the rotation of the inner core has stopped.
“We show startling observations that the inner core has almost stopped spinning over the past decade and may be reversing,” they wrote in the study.
“When you look at the decade between 1980 and 1990, you see a clear change, but when you look at the period from 2010 to 2020, you don’t see much change,” Song added.
The rotation of the inner core is driven by the magnetic field generated in the outer core and balanced by the gravitational effects of the mantle. Knowing how the inner core rotates could shed light on how these layers and other processes interact deep within the Earth.
However, the speed of this rotation, and whether it is variable, is up for debate, said Hrvoje Tkalczyk, a geophysicist at the Australian National University who was not involved in the study.
“The inner core never closes completely,” he said. He said the study’s results “mean that the inner core is now more in sync with the rest of the planet than it was ten years ago, when it was spinning a little faster.”
“Nothing catastrophic,” he added.
Song and Yang argue that, based on their calculations, a slight imbalance in the electromagnetic and gravitational forces could slow and even reverse the rotation of the inner core. They believe this is part of a seven-decade cycle and that the turning point prior to the one they detected in their 2009/10 data occurred in the early 1970s.
“The data analysis in the study is powerful,” said Tkalcik, author of Earth’s Interior: Revealed by Observed Seismology. However, the study’s findings “must be taken with caution” because “more data and innovative methods are needed to shed light on this intriguing problem.”
Song and Yang agreed that more research was needed.
Tkalcic, who devotes an entire chapter of his book to the inner circulation of the heart, suggested that the inner core cycle be every 20 to 30 years, instead of the seventy suggested by the last study. He explained why such differences occur and why it is difficult to understand what is happening in the interior of the planet.
“The bodies from our studies are buried thousands of miles under our feet,” he said.
“We use geophysical inference methods to infer internal features of the Earth, and care must be taken so that interdisciplinary results confirm our assumptions and conceptual frameworks,” he explained.
“You can think of seismologists as doctors who study the internal organs of patients’ bodies with imperfect or limited equipment. Therefore, despite progress, our picture of the Earth’s interior is still hazy, and we are still in the discovery phase.”