On March 28, Earth was hit by an X-class solar flare that was strong enough to ionize part of the planet's atmosphere.

Powerful X-class solar flare slams Earth, triggering radio blackout over the Pacific Ocean

Source: space
Source Link: https://www.space.com/powerful-x-class-solar-flare-slams-earth-triggering-radio-blackout-over-the-pacific-ocean