A small one actually occurred in AD 775.
Earth is often struck by solar flares — eruptions of particles, including electrons, protons, and heavy nuclei, that are ejected away from the sun into space when magnetic energy built up in the solar atmosphere is suddenly released. Those directed towards Earth encounter the magnetic field surrounding our planet, and this interaction results in beautiful auroras.
These solar flares are nothing compared to the eruptions seen on other stars, called “superflares.” Superflares have remained a mystery since they were first discovered in 2012. What perplexes astronomers the most is whether superflares are formed by the same mechanism as solar flares. And if that is found to be true, does that mean the sun is also capable of producing a devastating superflare?
Now, an international research team, led by Christoffer Karoff from Denmark’s Aarhus University,, has provided an answer to these questions, and they are a little alarming.
The results, published in the journal Nature Communications, show that the sun is capable of producing gigantic flares capable of breaking down radio communication and power supplies on Earth. In fact, the largest observed eruption took place on September 1, 1859, and on the morning of September 2, the particles reached Earth.
This event is known as the “Carrington Event.” Auroras could be seen as far south as Hawaii, telegraph systems around the world went haywire, and according to Greenland ice cores, Earth’s protective ozone layer was damaged by the particles.
However, there are stars capable of producing flares 10,000 times larger than the Carrington event.
Karoff and his team used observations of magnetic fields on the surface of almost 100,000 stars using the new Guo Shou Jing telescope in China to show that these superflares are likely formed via the same mechanism as solar flares.
“The magnetic fields on the surface of stars with superflares are generally stronger than the magnetic fields on the surface of the sun. This is exactly what we would expect, if superflares are formed in the same way as solar flares” explained Christoffer Karoff in a press release.
Considering the magnetic field of the sun is fairly weak compared to these other stars, it wouldn’t be capable to produce superflares, right? Wrong!
Out of all the stars with superflares that Karoff analyzed, around ten percent had a magnetic field with a similar strength to or weaker than the sun’s magnetic field.
“We certainly did not expect to find superflare stars with magnetic fields as weak as the magnetic fields on the sun. This opens the possibility that the sun could generate a superflare — a very frightening thought,” explained Karoff in the release.
Even though it is not very likely, it is possible that the sun could produce a superflare.
Evidence from geological archives has shown that the sun might have produced a small superflare in AD 775, and studies from the Guo Shou Jing telescope support the idea that a solar flare 10 to 100 times bigger than the largest solar eruption observed during the space age occurred.
Observations from the telescope can be used to evaluate how often a star with a magnetic field similar to the sun would experience a superflare. It turns out that, statistically, the sun should experience a small superflare every millennium.
If a large superflare hit Earth today, it would have devastating consequences not just for all our electronic equipment, but also for our atmosphere and the planet’s ability to support life.