How long to solar flares last?
C.O & J.O ANSWER: Most flares are quite short really, less than hour. The longest flare that we’ve seen with the Japanese Yohkoh satellite was 12 hours though. Compared to flares on other stars though the Sun is a bit of a wimp – some of those flares are a thousand times more energetic than the Sun and can last up to 10 days!