Earth’s inner core formed 1 billion years ago, says new research

Earth’s solid inner core was formed 1 billion to 1.5 billion years ago, “freezing” from the molten iron that currently forms our outer core, suggests new research published in the journal Nature.

Researchers from the University of Liverpool’s School of Environmental Sciences analyzed ancient igneous rocks and found that the Earth’s magnetic field jumped up in strength within that period, a possible an indication of the Earth’s core beginning to solidify.

The inner core is made up of solid iron and is larger than Pluto. According to the study’s lead author Dr. Andy Biggin, the results of their study suggest that the core is cooling down slower than theorized and is growing at an average rate of one millimeter a year.

“The timing of the first appearance of solid iron or ‘nucleation’ of the inner core is highly controversial but is crucial for determining the properties and history of the Earth's interior and has strong implications for how the Earth’s magnetic field—which acts as a shield against harmful radiation from the sun, as well as a useful navigational aid—is generated,” Biggin added.

The liquid iron in the outer core loses heat to the solid mantle layer above it, causing the liquid iron to move. This movement generates the magnetic field that protects Earth from excessive radiation. When the inner core solidified, this boosted the generation of the magnetic field.

“The theoretical model which best fits our data indicates that the core is losing heat more slowly than at any point in the last 4.5 billion years and that this flow of energy should keep the Earth’s magnetic field going for another billion years or more,” said Biggin. — Bea Montenegro/BM, GMA News