Our sun is not a peaceful place. It rotates by convection; The magnetic field closes, finds contact, closes again. It causes emissions of energy in the form of powerful flares and plasma in the form of coronal mass ejections. Most of this activity is not strong enough to harm us… but every once in a while the Sun shines with an explosion powerful enough to cause serious damage. And we don’t know how often such events occur. Previous estimates ranged from once a century to once a thousand years.

Okay guys, we have a problem. Because a new analysis of the explosion rate of 56,400 Sun-like stars has found that the Sun’s superflare rate is at the lower end of that scale, at about once every 100 years. If that’s the case, we might be in trouble, because even the famous Carrington event of September 1859 was only 1 percent stronger than a superflare.

“We were very surprised that Sun-like stars are prone to such frequent superflares,” says astronomer Valery Vasiliev of the Max Planck Institute for Solar System Research in Germany.

It is not easy to determine how often the Sun emits a huge amount of radiation. We cannot press the rewind button for replays. There are records of solar activity in tree rings that give us an idea (the largest storms caused by the Sun cause an increase in carbon-14 and nitrogen in polar ice), but they may not give us the full picture.

By looking for stars like our Sun (yellow G dwarfs) and hoping to catch some of them in the process of shining, researchers can estimate the frequency of large-scale events. There’s just one problem: We can’t always easily measure the rotation rate of these stars, and since rotation can be related to flare activity, the information we get from them is incomplete.

Vasiliev and his colleagues began their star search with two observations in mind. Sun-like stars with measurable rotation are generally more active than the Sun. And the stars most similar to the Sun have rotation periods that are difficult to measure.

They decided to use these two facts to access a large sample of Sun-like stars, including stars with unknown rotation rates but other properties (luminosity and temperature) most similar to the Sun.

They also excluded sun-like stars with orbital periods of less than 20 days (the Sun’s orbital period is 25 days). This is because the rotation of stars gradually slows down as the Sun ages; Therefore, young stars have higher rotation rates. Moreover, young stars are more active than older stars of the same type. They managed to obtain a sample of 56,450 sun-like stars and observed 2,889 superflares in 2,527 of them. This equates to a superflare frequency of approximately one every 100 years.

So what’s the problem with the Sun? We don’t know yet. We know it can cause epic tantrums. The Carrington event involved both a solar explosion and a coronal mass ejection that produced a powerful storm in the Earth’s magnetic field; It was the coronal mass ejection that did the most damage.

This is because coronal mass ejections can produce currents that then travel through the ground, disrupting and overloading infrastructure. The Carrington incident destroyed telegraph systems worldwide, and some overloaded networks caused fires. There was also a major geomagnetic storm in 1989 that affected many power grids and caused power outages.

Over the past 15,000 years, scientists have detected nine geomagnetic storms stronger than the Carrington tree ring event, known as Miyake events. The newest we find is 774 AD. Miyake events are estimated to occur approximately every 1000 years. However, not every explosion emitted by the Sun is accompanied by a coronal mass ejection.

“It is not clear whether giant explosions are always accompanied by coronal mass ejections and what the relationship is between superflares and extreme solar particle events,” explains astrophysicist Ilya Usoskin from the University of Oulu in Finland. “This needs to be investigated further.”

Solar flares have their own consequences; They can temporarily disrupt high-frequency radio communications by changing the density of the ionosphere where radio waves are refracted. However, given that the largest geomagnetic storms in history involve both solar flares and coronal mass ejections, it makes sense to be wary of possible superflare activity from the Sun.

Research shows we need to better understand how our Sun works, as the most effective defense against a massive geomagnetic storm is accurate prediction.

“The new data are a stark reminder that even the most extreme solar events are part of the Sun’s natural repertoire,” says astrophysicist Natalie Krivova from the Max Planck Institute for Solar System Research. The findings were published at: Science.