University of Alberta study links Earth’s core to millisecond shifts in day length
Researchers Huifeng Zhang and Mathieu Dumberry at the University of Alberta say competing forces between Earth’s core and mantle can explain day-length changes of a few milliseconds over decades. The finding offers a way to study the planet’s deep interior, though it will not affect daily life.
Bottom line — Zhang and Dumberry’s model links decades of rotation changes to a tug-of-war between gravity and forces at the core–mantle boundary.
Go deeper 5
-
Nature reports that the model matches observed day-length changes best when gravitational torque is the dominant force, opposed by electromagnetic and mechanical torques.
-
According to Nature, the inner core rotated slightly faster relative to the rest of Earth until around 2010, then began rotating more slowly.
-
ScienceDaily says the inner core’s uneven shape lets its motion interact gravitationally with unevenly distributed mass in the mantle.
-
ScienceDaily reports that Zhang and Dumberry’s model suggests the inner core deforms viscously on a timescale of about 10 years.
-
Yahoo News, citing Gizmodo, says the researchers compared statistical models with observational records spanning roughly six decades.