Earth's Solid Inner Core was Created 1 to 1.5 Billion Years Ago

Scientists have learned a bit more about Earth's inner core. They've used new data to find out that Earth's inner core was formed about 1 to 1.5 billion years ago as it "froze" from the surrounding molten iron outer core.

Researchers have long wondered when exactly the Earth's inner core was actually created. While there have been many estimates, though, researchers have been unable to pinpoint an exact date-until now.

The Earth's inner core is actually Earth's deepest layer. Today, it's a ball of iron just larger than Pluto, which is surrounded by a liquid outer core. This inner core is actually a relatively recent addition to our planet.

In order to find out exactly when it formed, the researchers in this latest study analyzed magnetic records from ancient igneous rocks. This revealed that there was a sharp increase in the strength of Earth's magnetic field between 1 and 1.5 billion years ago.

So what did this tell researchers about the inner core? The increased magnetic field is a likely indication of the first occurrence of solid iron at the Earth's center. In fact, it's likely that this magnetic field was created when the solid inner core first started to "freeze" out from the cooling molten outer core.

"This finding could change our understanding of the Earth's interior and its history," said Andy Biggin, the new study's lead author, in a news release. "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."

The findings are published in the journal Nature.

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