20:19 11 January 2017
Japanese scientists, who have been researching for the “missing element” within the Earth’s core, believe that the most likely candidate is silicon.
Lead researcher Eiji Ohtani from Tohoku University said: "We believe that silicon is a major element - about 5% [of the Earth's inner core] by weight could be silicon dissolved into the iron-nickel alloys."
The innermost part of Earth is composed of 85per cent iron and 10per cent nickel. As it is too deep to investigate directly, researchers who are trying to identify the missing element study how seismic waves pass through this region to tell them something of its make up.
Commenting on the research, Prof Simon Redfern from the University of Cambridge, UK, said: "These difficult experiments are really exciting because they can provide a window into what Earth's interior was like soon after it first formed, 4.5 billion years ago, when the core first started to separate from the rocky parts of Earth.
"But other workers have recently suggested that oxygen might also be important in the core."
He added: "In a way, these two options are real alternatives that depend a lot on the conditions prevailing when Earth's core first began to form.
"The most recent results add to our understanding, but I suspect that they are by no means the last word on the story."