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Earth’s core may have hardened just in time to save its magnetic field

This shift both prevented the protective magnetic field from collapsing and recharged it

Earth's magnetic field

SOLAR SHIELD  Earth’s magnetic field (illustrated) is powered by circulation of iron-rich fluid in the core. New research suggests Earth’s solid inner core formed after 565 million years ago, saving a weakening magnetic field from collapse.

Marc Ward/Shutterstock

By Carolyn Gramling

- More than 2 years ago

Earth’s inner core solidified sometime after 565 million years ago — just in time to not only save the planet’s protective magnetic field from imminent collapse, but also to kick-start it into its current, powerful phase, a new study suggests.