Explained: Dynamo theory
The Earth’s global magnetic field is generated in its metallic core, located nearly 3,000 kilometers beneath the planet’s surface. The field has existed on Earth for at least 3.5 billion years and offers clues about how other planets, stars and celestial bodies may have formed.As scientists refine their understanding of how this field works in their ongoing probe of planetary history, one idea they use to explain this process is dynamo theory — the idea that a large dynamo, or magnetic field generator, exists within Earth’s outer core, where liquid iron constantly moves as the planet cools. This continuous motion creates electric currents as electrons move through the liquid. Through this process, the energy of the moving fluid is converted into a magnetic field that can be sustained for billions of years. Knowing that planetary bodies like Earth, the Moon, Mars, and even asteroids have, or once had, a magnetic...