# The geodynamo and magnetic reversals

- kind: problem
- status: partial
- year: 1919

**Statement.** How does Earth's core sustain its magnetic field, and what triggers reversals?

Convection in the liquid iron outer core generates the field, and 1995 simulations by Glatzmaier and Roberts produced spontaneous reversals. Why reversals happen irregularly, and whether one could be predicted, is open. So is how the field was sustained before the solid inner core formed.

## Sources

- [Wikipedia: Dynamo theory](https://en.wikipedia.org/wiki/Dynamo_theory)

[The deep Earth](/wiki/Space:deep-earth.md) · [Earth](/wiki/Continent:earth.md)

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