From more than 3 billion years ago, the Earth has a very strong magnetic field

Previous studies have suggested that, in the early stages of development, the Earth is highly affected by the solar wind because its magnetic field is still weak. The atmosphere is blown away and the planet is immersed in a deadly radiation environment. But Roschester University geophysicists have recently published in Nature that the Earth's magnetic field from 3.2 billion years ago is nearly as strong today.

"Earth's early magnetic field intensity is very similar to the intensity of today," said John Tarduno, a professor at the University of Rochester physics. "The amazing thing is that this large magnetic field implies that the Earth has an iron-thick nucleus of 3.2 billion years ago. The theoretical models of Earth formation are almost don't show that. "

Earth is a giant magnet?

Tarduno's group separated granite from feldspar and quartz particles exposed to 3.2 billion years old in South Africa. But this mineral particle has been recorded in its structure characteristic of the ancient Earth magnetic field when they began to crystallize from molten lava. Tarduno used CO ₂ lasers to heat the crystal particles in an unprecedented way and used a super sensitive device (SQUID - Superconducting Quantum Interference Device) to measure the magnetic field of them. Measured values ​​range from 40 - 60 microtesla. "This means that the Earth's magnetic field actually existed from 3.2 billion years ago . " Tarduno said.

Confirmation results on earth magnetic fields measured on feldspar minerals ( Tarduno et al. Nature 446 (2007) 657 ).

To further confirm the result, Tarduno also examined the magnetic alignment in the particles, which reflected the distribution of ancient Earth's magnetic poles. By comparing with the directional distribution with other samples of the same age and the same location, Tarduno made sure that it was the trace created by the Earth magnetic field 3.2 billion years ago.

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