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The magnetic mystery at the center of the Earth

New research tackles the paradox surrounding the planet’s core

11:00am, September 4, 2015
computer simulation of Earth's magnetic field

FLIP FLOP  In a computer simulation, magnetic field lines (top row) twist and curl around the Earth’s liquid outer core. This magnetism results from swirling, or convecting, liquid iron (bottom row). The simulation mimics the process of a polarity reversal in which Earth’s north and south magnetic poles swap. Such reversals, a sign of a strong magnetic field generator, are seen going back hundreds of millions of years in planetary history.

Earth’s depths are a hellish place. More than 5,000 kilometers belowground, the iron-rich core scorches at temperatures comparable to the sun’s surface and crushes at pressures akin to the weight of 20 blue whales balanced on a postage stamp.

This extreme environment helps generate Earth’s magnetic field, the planetwide force that makes life on the surface possible. When the sun occasionally belches a blast of electrically charged particles at Earth, the magnetic field redirects the incoming bombardment. Without this magnetic defense, solar storms would fry any unsuspecting life-forms on the surface and gradually strip away Earth’s atmosphere.

For decades, scientists debated and fine-tuned their understanding of Earth’s magnetism. Heat flowing through the liquid outer core helps slosh the molten iron, generating a magnetic field, the general consensus holds. In the last few years, however, new investigations of Earth’s magnetic

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