Solar flares are classified using the X-ray brightness (see an explanation here), and "X class" flares are the strongest. The sunspot and magnetic active region complex that produced many M-class and X-class flares last month is back, and the EVE "flare-ometer" is hitting the red zone again.
EVE measures irradiance in the extreme ultraviolet (EUV), which are wavelengths slightly less energetic than X-rays. EUV variations in flux have a direct impact on the Earth's atmosphere and ionosphere, so EVE's measurements are essential for space weather forecasts.
EVE has a special flare observation mode that is triggered autonomously onboard SDO. EVE had 7 flare campaigns triggered in April, 8 in May, and so far there have been 8 in June. When combined with HMI and AIA, SDO is able to capture the magnetic structure and dynamics of space weather processes.
