The sun may appear constant but, like most things in the universe, it’s constantly in flux—cycling between an active state, called a solar maximum, and a more restful one, called a solar minimum.

It alternates regularly between these about every 11 years.

During solar maxima, sunspots increase but so do solar flares, making these times of increased irradiance.

Higher-than-normal electromagnetic radiation causes geomagnetic storms on Earth that impact GPS systems, satellites, and power grids.

Charged particles emitted can be hazardous to astronauts and spacecraft electronics.

More X-rays and extreme UV radiate toward Earth, but most are absorbed by the outer atmosphere, called the thermosphere.

The increased energy causes the thermosphere to expand, interfering with the orbit of satellites.

Conversely, during solar minima, solar flares and charged particle emissions are rare.

This is generally good news, since it means fewer geomagnetic storms and lower solar radiation risk.

However, there’s less solar energy to form ozone in the middle atmosphere, which allows more sunburn-producing UVB to reach Earth’s surface.

And reduced solar wind means that more cosmic rays can reach Earth.

Both solar states pose unique challenges. But for the most part, our atmosphere reacts to the increasing or decreasing energy and continues to protect us.