The implications of this change in the inner core’s movement for Earth’s surface can only be speculated. Vidale said the backtracking of the inner core may alter the length of a day by fractions of a second: “It’s very hard to notice, on the order of a thousandth of a second, almost lost in the noise of the churning oceans and atmosphere.”

The USC scientists’ future research aspires to chart the trajectory of the inner core in even greater detail to reveal exactly why it is shifting.

“The dance of the inner core might be even more lively than we know so far,” Vidale said.