Inner core’s rotation may have paused, reversed over 70 years.
The inner core of the Earth is a sphere of mostly pure, solid iron that is located 746 miles below the surface of the planet. It is surrounded by the liquid outer core which is composed of iron and nickel and creates the Earth’s magnetic field. Seismic waves caused by earthquakes and Cold War-era nuclear weapon tests have been used to study the inner core’s movement. A new study by seismologists Yi Yang and Xiaodong Song suggests that the inner core’s rotation has “paused” between 2009 and 2020 and could have even reversed. This could be part of a 70 year oscillation. Other theories suggest the inner core reverses its rotation more frequently and that it stopped rotating in the early 2000s. A separate study showed the inner core changed its spin between 1969 and 1974 and that it seems to oscillate a couple of kilometers every six years. Further research is needed to determine the exact behavior of the inner core.