Back in 1859, a powerful storm on the Sun launched colossal solar flares towards Earth, and the subsequent electrical surge triggered the shutdown of telegraph systems all over the planet.
According to a new paper in The Astrophysical Journal, there’s a solid chance that another such storm could impact Earth within 100 years – and this time around, the consequences would be far greater. Not only would it annihilate electrical circuits in a world covered in them, but it would also bring about an estimated $10 trillion worth of damage.
Avi Loeb and Manasvi Lingham, two renowned astrophysicists at Harvard University, have been concerned with the prospect of a so-called “superflare” for some time now. Unlike most, they’re far more worried about superflares than asteroid impacts or volcanic supereruptions.
They point out in their new study that, in the worst case scenarios, “the most powerful superflares can serve as plausible drivers of extinction events," and that "the risk posed by superflares has not been sufficiently appreciated.”
Using the geological record, along with data from other Sun-like stars, the pair worked out the frequency of various types of superflare impacting Earth. They found that extreme, atmosphere-eroding, extinction-level superflares occur on the Sun once every 20 million years. Additionally, they found that the chances of one able to cause major ecological and technological damage occurring within the next century is around one-in-1,000. A weaker one that just causes damage to electrical systems is even more likely, perhaps one-in-eight.
Just as a point of comparison, the chance of you witnessing a supervolcanic blast in your lifetime – something covered far more by the media – is around 90,000 times less likely compared to experiencing a type of superflare.
Just recently, these two researchers penned a study detailing how an Earth-sized magnetic shield could be used to defend ourselves from such an event. Although prohibitively expensive, perhaps it’s something that humanity should consider if the chances of a superflare event are so disturbingly high.
So what exactly is a superflare, compared to a regular solar flare? The difference, as you’d image, is in terms of its inherent energy.
Solar flares, accompanied by a flash of visible light, unleash about 100 quintillion joules of energy, along with plenty of electromagnetic radiation. These can occur every few days to a few times each day.
Superflares are far stronger stellar explosions, the type that releases up to 10,000 times more energy than regular flares. Just one involves at least enough energy to satiate the electricity demands of the entire planet for 14,700 years.
In either case, if pointing in the right direction, these flares take a few days to reach Earth, whereupon they impact the planet’s magnetic field and generate some spectacular aurorae.
If these flares are extremely energetic, however, the planet’s magnetic field experiences a huge increase in its electric current. This can trigger a geomagnetic storm, which if powerful enough has the potential to knock out satellites and electrical grids, and even partly strip away the ozone layer.
There was actually a near-miss in 2012. An explosion on the Sun produced not only plenty of flare-based electromagnetic radiation but a coronal mass ejection (CME) – a fountain of highly-magnetized solar plasma particles.
If these smashed into Earth’s magnetic field, they would certainly have generated a geomagnetic storm comparable to the 1859 event. Fortunately, the planet missed this CME by just nine days. If we had caught it, it would have caused widespread technological and economic damage.
Although several movies feature superflares boiling away the planet’s atmosphere, it’s generally thought that our Sun is nowhere near unstable or energetic enough to generate such Earth-destroying beasts.