Heliograph · field notes on a restless star
Seven moments when the Sun flashed brighter than its own surface and the Earth noticed. Scroll down through the record; the star beside it brightens to each event's X-ray class.
Descend1 September 1859
Richard Carrington was sketching a sunspot group when two beads of white light flared inside it, brightened, and faded within five minutes. Richard Hodgson saw the same thing through his own telescope. The magnetic storm arrived the next day: telegraph lines sparked, some operators sent messages on induced current alone, and aurora reached the tropics.
4 August 1972
With Apollo 16 home and Apollo 17 still months away, an active region fired a flare whose cloud crossed to Earth in about fourteen and a half hours, one of the fastest transits on record. Off the coast of Vietnam, magnetically triggered sea mines detonated with no ship in sight.
6 – 13 March 1989
An X15 flare opened a week of eruptions. On 13 March the resulting geomagnetic storm tripped protective relays across the Hydro-Québec grid, which collapsed in about ninety seconds. Around six million people waited roughly nine hours for the lights to return.
14 July 2000
On France's national day an X5.7 flare hurled a storm of energetic protons that speckled spacecraft cameras with false stars and blinded star trackers. It became one of the most studied eruptions of its cycle, a benchmark for every forecast model that followed.
4 November 2003
For two weeks around Halloween the Sun released flare after flare. The last, on 4 November, overwhelmed the X-ray detectors watching it: rated at least X28, with later reconstructions placing it higher still. Airlines rerouted polar flights and several satellites logged faults.
6 September 2017
Close to solar minimum, a modest sunspot group grew quickly and fired an X9.3 flare, the strongest of solar cycle 24. Shortwave radio faded across the sunlit Caribbean just as hurricane-relief operators needed it most.
10 – 14 May 2024
Region 3664 released a run of X-class flares and a train of eruptions that merged on the way out. On 10 May the first G5 storm in more than twenty years lit skies that rarely see aurora. Four days later, turning off the solar limb, the same region fired one last X8.7.
How flares are graded
Flares are ranked by their peak X-ray flux near Earth. Each letter is ten times brighter than the one before, and the number scales within the letter, so an X10 is a hundred times stronger than an M1.