Solar flares, massive energetic explosions that rise up from the Sun, can damage man-made satellites and pose a radiation hazard to astronauts. Despite decades of study, many aspects of this phenomenon are little understood.
Scientists do not know how big solar flares can get because we have only been tracking them since the beginning of the Space Age. A typical solar flare releases the energy equivalent to a billion hydrogen bombs and spew into space a hundred billion tons or so of deadly high-energy particles. Our magnetosphere and atmosphere block them like a giant sunscreen or divert them safely toward the poles where they produce our auroras.