Earth’s magnetic field is thought to be generated by the iron in the planet’s core. As it moves around, it produces electric currents that extend far into space. The magnetic field acts as a barrier, protecting Earth from the solar wind. This is a stream of charged particles from the Sun that could strip away the ozone layer if it were to impact the atmosphere.
When the magnetic field reverses—or attempts to—it gets weaker, leading to more radiation from the Sun getting through. Previously, scientists have linked extinction events to magnetic field reversals.