MEXICO: A Mercury-like body smashed into a young Earth and gave our planet’s core the radioactive elements necessary to generate a magnetic field, two Oxford geochemists say.
Without that magnetic field, there would be no shield to protect us from the onslaught of radiation constantly bombarding Earth from space, making the existence of life as we know it impossible, scientists say.
The study, published in the journal Nature, offers insight into how Earth’s magnetic field, and perhaps its moon, came to be.
Our planet is thought to have formed from small rocky bodies like the ones in the asteroid belt today, study co-author Bernard Wood, a geochemist at the University of Oxford, said in an interview. It’s a theory that fits quite well with what’s been studied on Earth, though it’s not a perfect fit, he said.
“That sort of roughly works, but there are all kinds of little questions that don’t quite work,” Wood said, “and one of them is, what is the energy source that drives the Earth’s magnetic field?”
Here’s the problem. To drive Earth’s magnetic field, you need radioactive elements like potassium, thorium or uranium – elements that give off heat as they decay – in the planet’s churning iron core. Those elements are attracted to oxygen and combine with it to make oxides, but oxides are really light and would float toward the planet’s surface; they wouldn’t be heavy enough to stay in the core. These elements also avoid contact with iron.
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