A solar flare is a sudden, intense release of energy in the sun’s outer atmosphere. The magnetic energy of a solar flare is released in the form of radiation at speeds of one million miles per hour (1.6 kilometers per hour). The amount of energy released is equivalent to millions of 100-megaton hydrogen bombs exploding at the same time. The frequency of solar flares is coordinated with the sun’s 11-year cycle. The number of solar flares is greatest at the peak of the solar cycle. Solar flares may be visible from Earth. The first solar flare observed and recorded was in 1859 by Richard C. Carrington (1826–1875) who saw a sudden white light while observing sunspots.