The solar corona is the outermost layer of the Sun's atmosphere, extending millions of miles into outer space. It is composed of superheated plasma and is visible during a total solar eclipse as a faint halo of light surrounding the dark silhouette of the moon. The corona is significantly hotter than the Sun's surface, with temperatures reaching millions of degrees Kelvin, and is the source of the solar wind that bathes the entire solar system in a stream of charged particles. Scientists study the solar corona to better understand its dynamic behavior, including solar flares, coronal mass ejections, and other phenomena that can impact space weather and Earth's magnetic field.