Solar flares are large (10-100 time the size of Earth) magnetic explosions on the Sun’s surface. They are categorized by their size. C-class is 10 times as powerful as B-class, M-class is 10x the size of C-class and X-class is 10 times the size of M-class. Flares are measured by the amount of x-rays arriving at the GOES satellite. With the solar flare browser, you can see the current x-ray count, and you can look at the profile of previous flares.
End Flare Flux Threshold:
Start To Peak Growth:
Hint: look at the decay rate, the lower it is, the more likely it is that the flare produced a CME – which is what will bring aurora to Earth when it arrives.