New evidence suggests that the Earth’s inner core oscillates over a six-year cycle

Study could explain why the Earth’s length of day oscillates over the same period.

A diagram of the Earth's layers and how they rotate, including the inner core which oscillated back and forth.
USC researchers identified a six-year cycle of super- and sub-rotation in the Earth's inner core, contradicting previously accepted models that suggested it consistently rotates at a faster rate than the planet’s surface. Credit: Edward Sotelo/USC