Earth’s inner core has stopped spinning faster than the planet’s surface and might now be rotating slower than it, finds a new study published in the journal Nature Geoscience. The study has been published by authors, Xiaodong Song and Yi Yang of China’s Peking University.
- The slowdown could change how rapidly the entire planet spins, as well as influence how the core evolves with time.
About Earth’s inner core
- The structure of the earth is divided into four major components: the crust, the mantle, the outer core, and the inner core. Each layer has a unique chemical composition, physical state, and can impact life on Earth’s surface. Movement in the mantle caused by variations in heat from the core, cause the plates to shift, which can cause earthquakes and volcanic eruptions.
- The solid inner core is situated about 3,200 miles below the Earth’s crust and is separated from the semi-solid mantle by the liquid outer core, which allows the inner core to rotate at a different speed from the rotation of the Earth itself.
- With a radius of almost 2,200 miles, Earth’s core is about the size of Mars. It consists mostly of iron and nickel, and contains about about one-third of Earth’s mass.
- The spin 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 interact and other processes deep in the Earth.
Key findings of study
- The study analysed seismic waves from repeating earthquakes over the last six decades. The researchers believe the inner core rotates, relative to the Earth’s surface, back and forth, like a swing.
- They studied seismic waves from earthquakes that have passed through the Earth’s inner core along similar paths since the 1960s to infer how fast the inner core is spinning.
- What they found was unexpected, they said. The inner core started rotating slightly faster than the rest of the planet in the early 1970s. But it had been slowing down before coming in sync with Earth’s rotation around 2009.
- Observations indicate that the inner core has nearly ceased its rotation in the recent decade and may be experiencing a turning-back.
- Song and Yang argue that, based on their calculations, a small imbalance in the electromagnetic and gravitational forces could slow and even reverse the inner core’s rotation.
Opposite views
- Some other scientists, not associated with study, argue that there is still much debate about the nature of the Earth’s core, because gathering information on it is extremely difficult.
- They say, till now no evidence are found suggesting that the change in the course or direction will affect the lives on the mother planet, Earth.
