Inner core of Earth stops spinning, may reverse direction.
Earth’s inner core is a hot iron ball the size of Pluto located approximately 3,100 miles below the Earth’s surface. It is able to spin independently due to its floating in the liquid metal outer core. Research published in the journal Nature Geoscience analyzed seismic waves from repeating earthquakes over the last six decades and found that the inner core’s rotation “came to near halt around 2009 and then turned in an opposite direction.” This rotation roughly lines up with changes in the “length of day” – small variations in the exact time it takes Earth to rotate on its axis.
The study’s authors, Xiaodong Song and Yi Yang of Peking University, believe that the inner core rotates back and forth like a swing, with one cycle taking about seven decades. This means it changes direction roughly every 35 years, and is predicted to do so again in the mid-2040s. What effect this has on surface dwellers is unclear, but the researchers believe there are physical links between all Earth’s layers.
Other theories have been proposed, with some suggesting the inner core oscillates far more quickly, changing direction every six years or so. Others believe the inner core only moved between 2001 to 2013 and has stayed put since, while another theory suggests its cycle is every 20 to 30 years.
Seismologists are like doctors studying the internal organs of patients’ bodies using imperfect or limited equipment, so our understanding of the inner Earth is still blurry. This could include more about a theory that the inner core might have yet another iron ball inside it – like a Russian doll. More research is expected to prove controversial, but it may take a decade to uncover more about the inner core’s movements.
News Source