Peeling the Layers

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Scientists have long thought that the Earth’s structure consisted of four layers: an outermost crust, then a mantle of molten silicate rock, a molten-liquid outer core and finally a metallic inner core.

Turns out, there is a fifth layer, CNN reported.

Decades ago, geoscientists suggested that there might be another hidden layer inside the core. Now, a research team conducted a study using new data sets gathered by analyzing earthquake seismic waves as they traveled through the Earth’s core.

They wrote that deep inside the center of the Earth there is a hidden “innermost inner core.” The newly detected center is around 400 miles wide and is comprised of an iron-nickel alloy – similar to the inner core.

The new layer has a distinct anisotropy, which is a trait of a substance that allows it to take on varied characteristics depending on the angle from which it is approached, the researchers explained.

For example, the team described a piece of wood as an anisotropic object: It’s much easier to hack a piece of firewood apart by hitting it along the direction of its grain than against it.

In the case of the innermost layer of the inner core, the researchers found that it changed the speed of seismic waves in a different way than the layer around it.

Co-author Thanh-Son Pham suggested the finding is important because it provides scientists with a better understanding of the Earth’s magnetic field and its evolution, as well as that of other planets.

“Take Mars as an example,” he said. “We don’t understand yet why (Mars’ magnetic field) ceased to exist in the past.”