We owe a lot to that big ball of gas in the sky that we call the sun. It provides life-sustaining light and heat energy to our modestly sized planet. Without the sun, we, and all the other millions of species that inhabit Earth, wouldn't be here. However, when you're dealing with a giant ball of electrically charged hot gas roughly 109 times the diameter of Earth, there's a lot of potential for chaos. Solar flares are one such chaotic event that has the potential to disrupt life as we know it.

Solar flares and coronal mass ejections (CMEs) are eruptions created on the sun's surface when the sun's magnetic fields become contorted by the sun's interior region.

Solar Flares and Coronal Mass Ejections in a Nutshell

Solar flares and coronal mass ejections (CMEs) are eruptions created on the sun's surface when the sun's magnetic fields become contorted by the sun's interior region. Both phenomena are giant explosions of energy, but they are different things. A Solar flare is essentially a brilliant and sudden flash of light. Solar flares can last anywhere from several minutes to several hours and contain enormous amounts of energy. By contrast, a CME is a colossal cloud of magnetised particles launched into space in a specific direction (sometimes Earth!). CMEs accompany the most powerful solar flares though not all solar flares.

Solar flares typically occur in "active" regions of the sun's surface. We can determine whether a region is active by looking for sunspots (areas of the sun that appear darker than the surrounding areas). But what causes sunspots? The exact science behind sunspot creation isn't known, but scientists know that it has something to do with interactions with the sun's magnetic field. The sun's magnetic field goes through cycles that we call solar cycles.

A solar cycle lasts approximately 11 years before the next cycle begins. Every 11 years, the sun's magnetic field flips (the north and south poles switch places). The solar cycle has an impact on solar activity on the sun's surface. The sun's surface becomes the most active (has the most sunspots) during the middle of the solar cycle. We call this period the solar maximum.

I was wondering what stage in the solar cycle we're experiencing right now? We've just entered solar cycle 25, and the sun's activity is expected to hit the solar maximum in July 2025 with an estimated 115 sunspots. This number is actually on the lower side of what we've seen in the past, with the average number of sunspots per cycle being 179.

How Big are Solar Flares?

In powerful coronal mass ejections, solar material can travel at over 1000 miles per second. The size of a typical solar flare is thought to be an enormous ten times the Earth’s diameter. 

The Classification of Solar Flares

Scientists classify solar flares by their strength. The four major categories are B, C, M, and X, with B being the smallest and X being the largest. It's a logarithmic scale, meaning an X1 is 10 times more powerful than an M1 flare, and an M1 is 10 times more powerful than a C1 flare. 

How Dangerous are Solar Flares?

Potentially very dangerous, but it all depends on the strength of the flare. C and B class flares are typically too weak to have any noticeable effect on Earth. However, as you move up the rankings, this starts to change. Some M class flares can cause brief radio blackouts around Earth's poles. This happens because the X-rays and UV radiation emitted by solar flares disrupt Earth's ionosphere (the shell of electrically charged particles surrounding Earth). The ionosphere is significant because it reflects radio waves we use for navigation and communication.  Or in other words, it helps us send messages around the globe.

Perhaps the most famous disruption caused by solar flares was the Carrington Event of 1859. This event happened during the Sun's 10th solar cycle and caused telegraph systems all over Europe and North America to fail. In some places, the telegraph operators even experienced electric shocks. If this event happened today, the impact on global communication would be staggering.