Scientists have now theorised that the inner core of the Earth is oscillating and it influences the length of the day. The new theory contradicts a previously accepted theory.
Earlier, it was believed that the inner core of the planet rotates at a speed faster than the surface. Now, researchers at the University of Southern California (USC) think the inner core is not only oscillating but also has changed direction in the past decades.
In all of Earth's layers, the inner core is found at the centre. It is followed by the outer core, lower mantle, upper mantle crust, and then atmosphere.
This is the first time seismic observation has led to a theory about six-year oscillation. Experts now think the inner core of the Earth is not fixed. It is moving under our feet and is going back and forth a couple of kilometres every six years.
Co-author of the study John E. Vidale cited two of the team's findings that indicate the oscillating nature of the inner core. They found the Earth's surface shifts compared to its inner core, as people have asserted for 20 years. He added that the inner core spun slower between 1969 and 1971. Experts also determined that the length of a day grew and shrank as would be predicted.
Scientists also observed that the inner core of the planet rotated slower than previously thought. A study in 1996 estimated the speed to be 1 degree per year. The latest research found it to be 0.1 degrees per year. Vidale and Wei Wang used seismic data from the Large Aperture Array (LASA) for the research.
The new findings are published in the journal Science Advances.