Earth's Inner Core Spins Faster than Earth Itself

For the past 300 years earth scientists have puzzled over which direction the center of the Earth spins, but a team of researchers from the University of Leeds claim to have solved the riddle.

Philip Livermore, from the School of Earth and Environment at the University of Leeds, and his colleagues contend that the Earth's inner core, which is made up of a Moon-sized orb of solid iron, "superrotates" in an eastward direction at a speed faster than the rest of the planet spins, while the molten iron outer core spins westward at a slower pace, its convection-driven movement generating a geomagnetic field.

This is the first time that researchers have been able to establish a link between the inner core and the behavior of how the outer core spins since 1692 when Edmund Halley presented evidence of westward-drifting motion of the Earth's geomagnetic field.

"The link is simply explained in terms of equal and opposite action," Livermore said. "The magnetic field pushes eastwards on the inner core, causing it to spin faster than Earth, but it also pushes in the opposite direction in the liquid outer core, which creates a westward motion."

To reach their conclusions the study authors used the supercomputer Mona Rosa at the Swiss National Supercomputing Centre in Lugano, Switzerland, to run a model of Earth's core, which enabled them to simulate the planet core with an accuracy about 100 times better.

"Other previous research based on archaeological artifacts and rocks, with ages of hundreds to thousands of years, suggests that the drift direction has not always been westwards: some periods of eastwards motion may have occurred in the last 3,000 years," the researchers wrote in a statement.  "Viewed within the conclusions of the new model, this suggests that the inner core may have undergone a westwards rotation in such periods."

The research, which is published in the journal Proceedings of the National Academy of Sciences, will enable scientists to better interpret the dynamics of the core of Earth, the source of our planet's magnetic field.