New Fact: Earth’s Magnetic Field Is 3.7 Billion Years Old, Same as the Origin of Life

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SPACE — New discoveries show that the Earth’s magnetic field was as strong 3.7 billion years ago as it is today. This means that our planet’s protective bubble formed and developed before our planet’s core solidified.

This timing places the formation of the magnetic field at the same time that life first appeared on Earth. The oldest fossils on the planet, namely layers of bacteria called stromatolites, are 3.5 billion years old. In fact, some researchers claim to have discovered 3.7 billion year old stromatolites.

New research shows that at that time, our planet already had a protective magnetic bubble around itself that deflected cosmic radiation and destroyed the sun’s charged particles. “However, the solar flow of charged particles was much stronger at that time,” said Earth scientist at the University of Oxford and lead author of the study, Claire Nichols.

According to him, the strong solar wind then removed the magnetosphere that protects the Earth, leaving our planet less protected than it is today. Findings published in Journal of Geophysical Research on April 24, 2024 it could have implications for the search for alien life.

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“When we look for life on other planets, the presence of magnetic fields is not the key. Because actually, with a much smaller magnetosphere, it seems like life could still develop,” Nichols told Live Science.

In fact, not all planets have magnetospheres, and researchers don’t know for sure what drives Earth to have such a protective system. Currently, the magnetic field is driven by the stirring of the liquid part of Earth’s core and the transfer of heat from the solid inner core to the convective outer core, as the core cools.

However, researchers estimate that the core had not yet solidified around a billion years ago. Nichols and his team traveled far to search for signs of ancient magnetic fields, 150 kilometers inland from Nuuk, Greenland, a place on the edge of the ice sheet that is only accessible by helicopter.

Rocks from the region, called the Isua Supracrustal Belt, are among the oldest surviving sections of Earth’s crust on the planet. These rocks contain iron-rich formations that store information about the direction and strength of the magnetic field when the rock was formed.

Researchers can also see folds in the rocks caused by geological upheavals. This helps them see whether the direction of the magnetic field matches the orientation of the rock. If the orientation does not match, it means the magnetic field existed before the geological event.

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Using this method, the researchers found that 3.7 billion years ago, the magnetic field had a strength of at least 15 microteslas. That’s half the average strength of today’s magnetic fields. But that’s a lower estimate, Nichols said, so it’s possible that the strength of the field was as strong then as it is now.

“Whatever is driving the magnetic field in the core, it is just as strong as it was before the core solidified,” Nichols said.

Researchers are now interested in digging deeper into the relationship between ancient magnetic fields and the Earth’s atmosphere. About 2.5 billion years ago, the atmosphere suddenly experienced a flood of oxygenation. “That’s partly due to the development of photosynthesis,” Nichols said. But, the strength of the magnetic field can influence which gases can remain in the atmosphere and which escape into space.