New Discoveries Solve a 300-Year-Old Problem—The Dynamics of the Earth's Core

Scientists at the University of Leeds have solved the 300-year-old riddle of which direction the Earth's core rotates.

While Earth's inner core, made of solid iron, is spinning eastward at a very high speed—meaning it's spinning faster than the rest of the planet—the outer core, made of molten iron, is spinning westward at a slower speed.

At the same time, Edmund Halley—the famous comet discoverer—observed a westward shift in the Earth's geomagnetic field in 1962. This was the first time scientists suspected that the Earth's inner core might be moving in response to the outer core. The planet behaved this way because it responded to the geomagnetic field.

The discoveries, published today in the Proceedings of the National Academies of Science, could help scientists understand the dynamics of the Earth's core and the source of our planet's magnetic field.

Measurements of earthquakes from the core made by seismometers over recent centuries have shown that the inner core must be rotating eastward with respect to the surface at supervelocity.

"The magnetic field forces the inner core to rotate eastwards, causing it to spin faster than Earth, while at the same time the liquid outer core spins in the opposite direction, giving the impression that the whole core is spinning westwards," said Dr Philip Livermore, from the School of Earth and Environment at the University of Leeds.

The solid inner core is about the size of the moon. It is surrounded by a liquid iron alloy, and the convection thrust of this outer core creates the geomagnetic field.

Source:

• Eurekalert-New insights solve 300-year-old problem: The dynamics of the Earth's core
  
• University of Leeds-New insights solve 300-year-old problem: the dynamics of the Earth's core
• Science News Line-New Insights Solve 300-year-old Problem: The Dynamics of the Earth's Core