"Fraunhofer discovered that the apparent continuity of a rainbow is an illusion. There are tiny gaps, dim or black arcs of missing colors, too narrow for us to see in the glare of natural rainbows. To say it another way, there are specific colors (specific wavelengths of light) in which sunlight is deficient. Fraunhofer eventually catalogued 576 of these gaps, or "absorption lines": 576 specific wavelengths missing from sunlight. Fraunhofer's career of discovery was cut short by consumption."