Life boomed on Earth half a billion years ago. You can thank magnets.

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Today, Earth's magnetic field acts as a safety blanket, shielding the planet from dangerous solar wind. Without the protection of our magnetosphere, you, me and almost every other living thing on Earth would not fare very well being pummeled by streams of harmful particles from the sun.

But there was a time — half a billion years ago, give or take — when Earth's magnetic field became much weaker. And that magnetic collapse might have actually helped spark an explosion of life on Earth.