In 1859, a massive solar flare bombarded Earth with so much energy that telegraph wires burst into flames, and stunning auroras could be seen as far south as Cuba and Hawaii. Such a powerful event would likely be devastating for our modern world, with the potential to knock out satellites, electrical grids, and technology worldwide. But when can we expect the next superflare? Astronomers at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, studied 84 sunlike stars and observed 29 of these supersized solar flares over a 4-year period to find out how often they occur. Good news! A star like our sun will probably experience such an extreme flare only once every 250 to 480 years—astronomers say 350 years is the most likely scenario. The team presented its findings in a poster at the International Astronomical Union General Assembly in Honolulu this month. Just how “super” is a superflare? The eruptions the team studied to make their prediction were 150 times more powerful than an average flare and at least 10 times more powerful than a 1989 flare that knocked out power to the entire province of Quebec, Canada.