Seismic data shows that the core is spinning the other way. Should we worry?

A recent study reports that the Earth’s inner core has stopped spinning in the same direction as the planet and may have even started spinning in the opposite direction. This study fuels the debate among scientists on how exactly the Earth’s inner core spins.

The Earth is divided into four layers: the inner core, the outer core, the mantle, and the crust. The innermost layer, the inner core, is a hot iron ball the size of Pluto. This inner core is found around 5,000 kilometers (3,100 miles) below the surface of the Earth. The outer core is 2,260 kilometers (1,400 miles)-a thick, hot, liquid layer mostly made of nickel and iron. According to scientists, this inner core can spin on its own because it floats in the liquid metal outer core. Thus, the direction in which the inner core spins remains a topic of debate.

The recent study was published in the Nature Geoscience journal. In the study, scientists Xiaodong Song and Yi Yang observed records of the seismic waves from earthquakes over the last six decades. Seismic waves are vibrations made by earthquakes within the Earth or at the Earth’s surface. Through their observations, they found that the Earth’s inner core stopped spinning in the same direction as Earth in 2009. Then, the Earth’s inner core began to spin in the opposite direction.

Song and Yang believe that the Earth’s inner core rotates back and forth like a swing compared to the Earth’s surface. They also reported that the Earth’s inner core changes the direction in which it spins approximately every 35 years. According to Song and Yang, the Earth’s inner core changed its direction in the early 1970s, then again recently in 2009, and will change its direction again in the mid-2040s.

As of now, there is no information on whether the direction of the spin of the Earth’s inner core has any effect on the Earth’s surface. However, scientists have noted that this rotation of the Earth’s inner core matches the Earth’s length of day. Song and Yang believe that all of the four layers of Earth are somehow linked. Through their study, they wish to inspire other scientists to consider Earth as a united, dynamic system.