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At some point in Earth's 4.5-billion-year history, its entirely liquid iron core cooled enough to form a solid ball in the centre. Today, our planet's core consists of a solid iron inner core surrounded by a molten iron outer core, but pinning down exactly when this change occurred has proven quite difficult.
Estimates range from 4.5 billion years ago - the age of Earth itself - to 565 million years ago; now, a new study has finally narrowed it down. According to data obtained in laboratory experiments that create conditions approaching those in the planetary core, the age of the inner core should be somewhere between 1 billion and 1.3 billion years.
In turn, this helps us to narrow down the age of the geodynamo, which powers the magnetic field around Earth. This magnetic field contributes to conditions hospitable to life as we know it by protecting the planet's atmosphere from being blown away by the solar wind.
Therefore, it will come as no surprise that scientists are deeply interested in how it came to exist, and how it is maintained.
"People are really curious and excited about knowing about the origin of the geodynamo, the strength of the magnetic field, because they all contribute to a planet's habitability," said geoscientist Jung-Fu Lin of The University of Texas at Austin.
The geodynamo is created by the circulation of conducting iron in the outer core, driven by convection that's powered by two mechanisms.
Scientists Just Narrowed Down The Age of Earth's Inner Core
At some point in Earth's 4.5-billion-year history, its entirely liquid iron core cooled enough to form a solid ball in the centre.
www.sciencealert.com