Days on Earth are getting longer.
The days really are getting longer
New research has found that changes to the planet's inner core are having a subtle impact on the length of days.
Studies of earthquake data have revealed that the inner core began to slow in 2010 and is now moving backwards with an effect on Earth's rotation in space.
However, the experts say that the changes might be very difficult to spot.
Professor John Vidale, an Earth scientist at the University of Southern California, said: "When I first saw the seismograms that hinted at this change, I was stumped.
"But when we found two dozen more observations signalling the same pattern, the result was inescapable. The inner core had slowed down for the first time in many decades."
He added: "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."