Superflare
Since superflares can occur on stars apparently equivalent in every way to the Sun, it is natural to ask if they can occur on the Sun itself. An estimate based on the original Kepler photometric studies suggested a frequency on solar-type stars (early G-type and rotation period more than 10 days) of once every 800 years for an energy of 10 erg and every 5000 years at 10 erg. One-minute sampling provided statistics for less energetic flares and gave a frequency of one flare of energy 10 erg every 5–600 years for a star rotating as slowly as the Sun; this would be rated as X100 on the solar flare scale. This is based on a straightforward comparison of the number of stars studied with the number of flares observed. An extrapolation of the empirical statistics for solar flares to an energy of 10 erg suggests a frequency of one in 10,000 years.
Solar cycle 24
Then, on September 22, an X1.4-class solar flare erupted out of sunspot 1302. A R3-level radio blackout was registered. The blast produced a significant CME, but was not Earth directed. Two days later, an X1.9-class flare followed in the next 31 hours by a spectacular string of 14 M-class flares, being the biggest two M7 flares, were mostly unleashed out of the same sunspot. The first two explosions, X1.9 and M7.1, propelled a pair of closely spaced CMEs. A G4 (severe) geomagnetic storm was reported on September 26.