What is a solar flare?

A solar flare is a powerful eruption of electromagnetic radiation from the Sun surface, triggered when twisted magnetic fields, usually around sunspots, suddenly snap and reconnect, releasing enormous stored energy. Flares emit radiation across the spectrum, from radio waves to X-rays and gamma rays, and can release the energy equivalent of millions of hydrogen bombs in minutes. They often accompany coronal mass ejections, huge clouds of charged particles hurled into space. When this radiation and these particles reach Earth, they can disrupt radio communications, GPS, and power grids, and they intensify the auroras. Flares are classified by strength using letters, with X-class being the most powerful. Solar activity, including flares, rises and falls over an approximately 11-year cycle.