A NASA spacecraft has witnessed hundreds of "superflares" coming from sunlike stars—and the observations suggest that the trigger for such massive outbursts remains a mystery.
On our sun, solar flares aimed at Earth can send huge amounts of energy colliding with our planet. If a flare is strong enough, it can cause a solar storm that might cripple satellites and even knock out the power grid.
Astronomers have also recorded similar but much more powerful flares coming from a variety of stars. These superflares can be millions or even a billion times more powerful than an average sun eruption, packing enough energy to roast nearby planets whole.