At the center of the Earth is a metal ball whose rotation is independent of the rotation of the planet, like a circle rotating within a larger circle.
This mysterious movement at the Earth’s core has intrigued the scientific community since it was discovered by Danish seismologist Inge Lehmann in 1936.
Motion and its properties, such as its speed and direction, have been the focus of scientific debate for decades.
Several recent findings suggest that the core’s spin has undergone dramatic changes in recent years, although scientists have yet to reach a consensus on the causes or effects of these changes.
Part of the problem with analyzing the nucleus is that it is impossible to directly observe or sample.
Seismologists have been able to obtain information about the movement at the Earth’s center by examining the waves generated by large earthquakes that originate in that region.
Differences in the behavior of waves of similar intensity that passed through the core at different times allowed scientists to measure changes in the position of the metal center and calculate its rotation.
Latest results on the nucleus
Changes in the core’s rotation have been analyzed since the 1970s and 1980s, but seismic evidence wasn’t published until 1990, Dr. Lauren Wasik, a professor of physical sciences at James Cook University, told CNN Australia.
Due to the difficulties of accurately determining observations around the core, subsequent results have failed to reach a consensus on the rotation rate or direction.
But the model proposed in 2023 describes a core that once rotated faster than Earth itself, but now moves more slowly.
The report is published in the scientific journal Natural Earth Sciences In January 2023, it states that the core has slowed down even more and has begun to move in the opposite direction to the fluid moving in its envelope.
At the time, some experts argued that more data was needed to support these conclusions, and now a team of scientists has released results that support the 2023 hypothesis.
In an article published in the scientific journal nature, Not only did scientists confirm that the core was slowing down, they confirmed that the slowdown was part of a pattern of changes that occurs every 70 years.
The new findings confirm this hypothesis, said Dr. John Vidal, co-author of the latest study and dean of earth sciences at USC Dornsife College of Letters, Arts and Sciences.
Vidal added that the conclusion that the core changes its rotation every 70 years was made possible by analyzing specific points where seismic activity was recorded between 1991 and 2023 from South Georgia and the South Sandwich Islands, in the Atlantic Ocean, to the southernmost region of South America.
Effects on the Earth’s magnetic field
Although some experts still insist that more evidence is needed to clearly determine the dynamics of the core’s motion, other scientists say that the Earth’s magnetic field could be linked to this rotation.
Earth’s solid metal core is buried about 3,220 miles inside the planet. Surrounding the core is an outer layer of liquid metal.
The planet’s core is composed primarily of iron and nickel, and its temperature is estimated to be about the same as the surface of the Sun, about 9,800 degrees Fahrenheit.
The Earth’s magnetic field pulls on this hot metal ball, causing it to spin. At the same time, gravity and the flow of fluid in the outer layers also affect the core.
Over the decades, these magnetic dynamics have caused variations in the core’s rotation speed, Vidal added.
The effects of the metallic fluids on the outer layer of the core generate electric currents that activate the Earth’s magnetic field, which protects the planet from deadly solar radiation.
Although the direct effects of the core on the magnetic field are still unknown, scientists reported in 2023 that the slower rotation of the core could affect the field and shorten the length of the day.
However, Vidal said, changes in the core’s rotation are almost imperceptible to people on Earth’s surface.
When the core moves faster, the mantle also speeds up. That makes the Earth spin faster and the days get shorter. But Vidal said these rotational changes only last for fractions of a second a day.
Scientists study the Earth’s core to understand how the planet’s interior formed and how its activity relates to subsequent layers.
“New and emerging methodologies will be essential to answering current questions about the Earth’s core, including its rotation,” added Vashek, the Australian academic.
Experts say the Earth’s core has stopped and the planet’s rotation may have changed direction.
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