The Sun is a huge ball of boiling gas (plasma) with loop-like structures on the solar surface which are associated with the magnetic field of the Sun. When one of these loops becomes unstable, it breaks off from the surface of the Sun and creates a solar flare. The biggest flares can be hundreds of times the size of the Earth. Five categories — A, B, C, M and X — are used to rank solar flashes associated with solar flares based on their intensity. A-class flashes are the weakest, while X-class flashes are the most energetic. Solar flares are seen by the photons (or light) released across the spectrum. X-rays are the primary wavelength monitored in the classification of solar flares. Flares also contribute to the acceleration of protons and other charged particles that may accompany a significant event.
For more information on the effects of M and X class flares, see the Radio Blackouts Scale.