Earth’s solid metallic core may no longer spin relative to the vast mass of the surrounding planet thanks to what appears to be a recent slowdown, according to the results of a new study.
Nestled in the heart of our planet is a vast ball of solid metal 2,400 km wide, which is surrounded by an outer core composed of superheated liquid iron and other materials.
This liquid barrier acts to separate the solid inner core from the vast surrounding Earth mass, allowing it to spin independently. Scientists have long believed that the central core spins much faster than our planet’s outer mantle and crust.
Beautiful photos of Earth from space
This phenomenon, known as super-rotation, is believed to be partly responsible for generating Earth’s protective magnetic field, and may even impact ocean temperatures and the length of each day.
However, according to new research published in the journal Nature Geoscience, the speed of the core may have slowed considerably over the past few decades.
In the recent study – reported by Vice – a team of scientists analyzed data from seismic waves created by powerful earthquakes that passed through our planet’s crust and interacted with the inner and outer core. These earthquakes occurred mostly between 1995 and 2021 in locations spread across the globe.
Some geologists believe that the rotation of the central core affects the time it takes for seismic waves to travel through the planet and that by tracking the variations in the speed of the waves that occur in close proximity to each other they are able to measure the speed of rotation. of the earth’s core. Previous studies have used this technique to estimate that the huge ball of metal rotated about a tenth of a degree faster than the surrounding mantle each year.
However, according to the results of the new study, the Earth’s core may now have stopped rotating relative to the rest of the planet. According to seismic data, the shift may have taken place as early as 2009, and the core may now be on the verge of entering a period of “underrotation”, in which it will spin slower than the rest of our world.
“There are two major forces acting on the inner core,” study authors Yi Yang and Xiaodong Song of Peking University told Motherboard. “One is the electromagnetic force. The Earth’s magnetic field is generated by the movement of fluids in the outer core. The magnetic field acting on the metallic inner core should cause the inner core to rotate by electromagnetic coupling.
“The other is the force of gravity. Both the mantle and the inner core are very heterogeneous, so the gravity between their structures tends to pull the inner core towards the position of gravitational equilibrium, called gravitational coupling.
According to the researchers, imbalances between the two forces can cause the nucleus to accelerate or decelerate. To their surprise, the pair also discovered that the core also appeared to have stopped rotating independently of the mantle in the early 1970s, suggesting that its rotation could naturally change in a recurring 70-year cycle.
However, it should be noted that not all scientists agree that the core is spinning faster than the rest of the Earth, and instead suggest that aberrations in the travel time of seismic waves could instead result from changes to the surface of the vast metal core.
Yang and Song are now waiting for more earthquakes to send seismic waves through the core to further test their theory. NASA also plans to launch a mission to explore what could be the exposed metallic core of an ancient, shattered planet, which could shed light on the inner workings of Earth and the other worlds that inhabit our solar system.
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Anthony is a freelance contributor covering science and gaming news for IGN. He has over eight years of experience covering groundbreaking developments in multiple scientific fields and has absolutely no time for your shenanigans. Follow him on Twitter @BeardConGamer
Image credit: Vadim Sadovski