Recently at the Fall Meeting of the American Geophysical Union in San Francisco, the team from Tohoku University presented their result of research. They ‘ve been searching for the missing element of Earth’s inner core for decades. As it is well known, the biggest part of inner core takes the iron, approximately 85 percent. Around 10 percent takes a nickel. The rest of 5 percent were a mystery, until now.

An artist’s impression of the iron jet stream within the liquid outer core as detected by the three swarm satellites, ESA

Missing Element Of Earth’s Inner Core

The Earth’s solid inner core has a radius of 1,500 miles. The first time it is discovered by Danish seismologist Inge Lehmann in 1936. She is, based on observation, concluded that Earth has a solid inner core distinct from its liquid outer core. The outer core ( known as a liquid core too ) is a fluid layer about 1,400 miles thick. It is composed mostly of iron and nickel. Somewhere after 3,200 miles beneath the Earth’s surface, the outer core enter to the solid core, which radius is 745 miles. Those two cores have dynamic interactions which give our planet magnetic field. As the temperature of the inner core is 5,400 °C, it is clear why it was difficult for researchers to figure out all the elements.

The internal structure of Earth

As it’s impossible to directly study the solid core due to its depth, Japanese scientists create mini Earth core in the laboratory. They mixed familiar ingredients of inner core – iron and nickel – then added silicon. After mixing, they put it under the pressure and temperature, to imitate conditions from the solid core. The comparations of real seismic data to the results of experiment completely matched. Although the idea that the silicon is a missing element is not new, the result of the experiment now it confirmed.

Silicon in its pure elemental form – now it’s confirmed it makes 5% of inner core

Lead team member professor of petrology and geophysics Eiji Ohtani told that the presence of silicon doesn’t expel the presence of some other elements. With him agreed on Professor Simon Redfern, from the University of Cambridge who told the BBC News: “These difficult experiments are really exciting because they can provide a window into what Earth’s interior was like soon after it first formed. The most recent results add to our understanding, but I suspect that they are by no means the last word on the story.”