Earth’s hot interior is composed of a solid inner core of iron and nickel that is surrounding by a fluid outer core. In 1996, scientists first speculated that the Earth’s inner core was rotating faster than the rest of the planet, but the idea was controversial. The rotation of the inner core is believed to be driven by circulating liquid caused by heat-induced convection currents in the outer core.
For the past decade, scientists have been further investigating the rotation of the Earth’s inner core by analyzing seismic waves that pass through the interior of the Earth. Earthquakes produce seismic waves.
Research published in Science in 2005 and more recently in the February 2011 issue of Nature Geoscience confirms that Earth’s inner core does indeed rotate faster than the rest of the planet. The 2011 estimates suggest that the extra spin may be on the order of 0.1 to 1 degree every million years, a much slower estimate than the values proposed in 1996 and 2005.
The hallmark of good science is that the results are repeatable. Now three scientific studies have confirmed the hypothesis that the Earth’s inner core rotates faster than the rest of the planet. Accurate geophysical information on the structure and movement of the Earth’s interior may help science to develop a more robust understanding of how the Earth generates a magnetic field that is essential to life on the planet.
Deanna Conners is an Environmental Scientist who holds a Ph.D. in Toxicology and an M.S. in Environmental Studies. Her interest in toxicology stems from having grown up near the Love Canal Superfund Site in New York. Her current work is to provide high-quality scientific information to the public and decision-makers and to help build cross-disciplinary partnerships that help solve environmental problems. She writes about Earth science and nature conservation for EarthSky.