When Will the Next Solar Superflare Hit Earth?

Every now and then, the sun shoots high-energy protons into space, creating solar flares and wreaking havoc on Earth. But though the most dangerous solar flares could still be in the future, it could take them a while to materialize.

As Ilima Lewis reports for Science, a team at the Harvard–Smithsonian Center for Astrophysics recently observed 84 stars across the universe that bear similarity to the sun, analyzing their behavior during 29 massive solar flare events. By their calculations, extreme solar flares, or superflares, only happen every 250 to 480 years — a cycle that's likely 350 years long for this solar system.

Radiation from solar flares can harm astronauts living aboard the International Space Station, and in 1859, a powerful flare sent a solar storm on a collision course for Earth. The geomagnetic storm set telegraph wires aflame and lit up the sky with unusual worldwide aurorae.

So what would happen if a massive superflare caused a solar storm on Earth today? As Ask Smithsonian explained back in January, such storms bring lots of scary possibilities, especially for a world so dependent on electricity. Fortunately, it looks like Earth still has plenty of time to prepare — that is, if you consider 194 years plenty of time.

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Helen Thompson writes about science and culture for Smithsonian. She's previously written for NPR, National Geographic News, Nature and others.