The solar flare last November was more than twice as big as the previous recorded explosion - and so violent that satellite detectors were unable to record its true scale because they were blinded by its radiation.
Their calculations showed the flare's X-ray radiation striking the atmosphere was equivalent to that of 5,000 suns, although they said none of it reached the earth's surface.
The flare was not on a direct course and harmful radiation was absorbed by the magnetosphere, a protective layer around the earth.
The flare came during a spell of extraordinary solar activity, when the sun produced a series of vast explosions.
An accompanying aurora was seen over the skies of southern England. At the time one scientist described the power of the flare as being greater than "every nuclear warhead being detonated at once".
It makes you wonder, if one of these flares was to hit a passing comet what would happen? :)