What would happen if Earth’s magnetic field “turned off” for one day?

We’re answering a question from one of our subscribers:

What would happen if Earth’s magnetic field turned off for one day?

Earth’s magnetic field deflects the solar wind away from the planet, preventing it from bombarding the atmosphere. It acts on the world similarly to ionizing radiation. If Earth’s magnetic field were to disappear for an extended period, the radiation levels on the planet’s surface would become lethally dangerous to most existing organisms.

It would lead to mass extinctions of many animal and plant species within a relatively short time, but life might adapt to such conditions in the long run.

Additionally, the solar wind would gradually erode the planet’s atmosphere. It has already happened with Mars in the past. Mars once had a fairly dense atmosphere and apparently liquid water oceans on its surface, but after losing its magnetic field, the atmosphere began to escape gradually. However, this process is not fast, and in the case of Earth, it would occur much more slowly than on Mars. It would take millions of years for the effect to become noticeable.

If the magnetic field were to disappear for just one day, we wouldn’t notice much, except that we would see auroras all over the planet, not just at the…