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.