A solar flare is a powerful, localised burst of electromagnetic radiation in the Sun's atmosphere.
Flares occur in active regions and are frequently, but not always, associated with coronal mass ejections, solar particle events, and other solar phenomena.
The frequency of solar flares changes during the course of the 11-year solar cycle.
Solar flares, which appear as brilliant spots on the Sun, can last from a few minutes to several hours.
The photons (or light) emitted by a solar flare are often detectable at nearly all wavelengths.
The primary means for tracking flares are X-rays and optical light.
Flares also accelerate particles such as electrons, protons, and heavier particles.
Solar flares' high-energy electromagnetic radiation is absorbed by the daytime side of the Earth's upper atmosphere, particularly the ionosphere, and does not reach the surface.
Flares can also occur on other stars, which is why the term stellar flare is used.