Book 21, Question 52
How Does Swirling Liquid Metal Deep Inside Earth Make a Magnet?
Deep under your feet, a layer of melted metal swirls around and around. That swirling is what makes Earth's magnetic field. The outer core is about 1,400 miles thick.
More fun facts
- Earthquake waves show that Earth has a dense liquid core about half the radius of the planet, with a solid inner core inside it.
- The liquid core is thought to be molten iron, perhaps mixed with nickel and sulfur.
- Earth's outer core is in turbulent convection, driven by radioactive heating and chemical changes.
- As the electrically conducting iron moves through Earth's magnetic field, it creates electric currents.
- Those currents make their own magnetic field, so the process keeps itself going as long as the core keeps churning.
- Scientists call this self-sustaining process a dynamo.
Sources: NASA, U.S. Geological Survey
Questions kids ask
What keeps Earth's magnetic field going?
Churning liquid iron in the outer core makes electric currents, and those currents keep making the magnetic field.