The Sun's Atmosphere

The material in the Sun farther out from the center than the photosphere makes up the Sun’s atmosphere. The atmosphere extends far beyond the disk we see in the sky. Very diffuse solar gases extend all the way to Earth and beyond.

The solar atmosphere consists of, from the innermost part outward, the photosphere, the chromosphere, the corona, and the expanding outer layers of the corona that astronomers call the solar wind. The photosphere is the visible part of the Sun. We look right through the chromosphere, the corona, and the solar wind, just as we see through Earth’s atmosphere at night.

The chromosphere and corona are visible during total solar eclipses, when the Moon lines up between the Sun and Earth, completely blocking the main disk of the Sun from view. The thin chromosphere becomes visible a few seconds before or after a solar eclipse, creating a narrow pink, rose, or ruby-colored band at the edge of the Sun. For up to eight minutes during an eclipse, the corona is visible to the unaided eye as a faint, shimmering halo of pearl-white light spreading out from the lunar silhouette. Although the light of the chromosphere and corona is not bright enough to be dangerous, and can be viewed safely without filters during the total phase of an eclipse, the partial phases of a solar eclipse are very hazardous to human eyes and can only be viewed indirectly or through special filters. Scientists can study all layers of the Sun’s atmosphere at any time using special instruments.