Spectroheliograph

The spectroheliograph was invented to photograph the Sun's spectrum in a small band of wavelengths, aiding in detailed study of its outer chemistry. It enabled the examination of specific wavelengths like calcium.
George Ellery Hale United States 1890
Spectroheliograph

The spectroheliograph was invented to photograph the Sun's spectrum in a small band of wavelengths, aiding in detailed study of its outer chemistry. It enabled the examination of specific wavelengths like calcium.