Last summer, weather agencies all over the globe issued alerts as solar weather in the form of charged particles and coronal mass ejections headed toward Earth. There was the possibility of strong solar — or geomagnetic — storms, but what exactly would that mean for us? What is a solar storm, and what is space weather generally? Could these forces pose a threat to human life?

Many think of space as cold and unchanging, but space weather is actually quite dynamic, and charged particles and radiation (mostly from the sun) do travel through space and affect Earth. Read on to learn more about solar storms, the sun's solar cycles, and what effect they can have on Earth.

What Is a Solar Storm?

The sun is an incredibly volatile and often violent place, and it produces quite a bit of activity on a regular basis. According to NASA, solar activity can come in many forms, including solar flares, solar wind (or charged particles), and coronal mass ejections (CMEs). The specific solar weather event that triggered alerts from August 17—19, 2022 was a mix of CMEs and solar wind coronal mass ejections (CWMEs). A CWME is a release of gas and magnetic fields from the sun's atmosphere, the corona, while solar flares are a burst of radiation from the sun's surface due to sunspots.

It's important to note that not all solar storms affect Earth. They have to be directed at the planet to affect conditions here. Generally speaking, CMEs, solar flares, and energetic particles continue traveling in the direction they took at the point of eruption. If Earth is in that path, our planet will be affected.

Why Does the Sun Produce Solar Storms?

The sun goes through regular cycles. Over the course of 11 years, the sun's activity builds to a maximum. When it peaks, the magnetic field of the sun actually reverses — the north pole becomes the south pole, and the south pole becomes the north pole. Once that occurs, the sun starts cycling back to minimum activity.

Scientists think the sun reached its most recent period of minimum activity in 2019, which means in 2020, we entered Solar Cycle 25. We're now in a period of increasing solar activity that will peak in July 2025.

All of this is approximate, of course. To measure solar storms and the sun's cycle, scientists use sunspots, which are dark, cooler areas on our star's surface that occur when parts of the sun's strong interior magnetic field rise to the surface. They also produce solar flares and CMEs. You can see what sunspots are currently on the sun at any given time using NASA's Solar and Heliospheric Observatory camera.

Effects of Solar Weather on Earth

Now that we've established what solar storms are, let's look at the impact of August's geomagnetic event on Earth. On August 17, a coronal mass ejection sent charged particles from the sun toward the planet. The NOAA's space weather division classified it as a G2 storm, which is "Minor to Strong."

According to the NOAA, the storm started out as minor due to solar wind that traversed through a coronal hole, a gap that allows charged particles of solar wind to escape the sun more freely. These particles impacted Earth on August 17, causing a minor solar storm. However, emanations from multiple CMEs were also on their way to Earth and reached the planet on August 18, making the solar storm stronger.

A particularly strong solar storm could have serious effects, such as knocking out power or disrupting cell phone service, satellites, or GPS. The effects of the recent storm, though, were relatively minor, and as with any geomagnetic storm, people were treated to stunning aurora in the night sky.

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