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Fraunhofer lines
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solar spectrum A horizontal diagram of the visible solar spectrum displays colors from violet to red, labeled with wavelength values in nanometers and prominent Fraunhofer lines marking where elements like hydrogen, magnesium, and sodium absorb light. A horizontal gradient bar displays the visible light spectrum from violet to red, labeled with corresponding frequency in terahertz, wavelength in nanometers, and photon energy in electron volts.
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Nicolaus Copernicus. Nicolas Copernicus (1473-1543) Polish astronomer. In 1543 he published, forward proof of a Heliocentric (sun centered) universe. Coloured stipple engraving published London 1802. De revolutionibus orbium coelestium libri vi.
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Joseph von Fraunhofer
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Fraunhofer lines

physics
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History

Fraunhofer lines, in astronomical spectroscopy, any of the dark (absorption) lines in the spectrum of the Sun or other star, caused by selective absorption of the Sun’s or star’s radiation at specific wavelengths by the various elements existing as gases in its atmosphere. The lines were first observed in 1802 by the English physicist William Hyde Wollaston but are named for the German physicist Joseph von Fraunhofer, who from about 1814 plotted more than 500 of them and designated the brightest by the letters A through G, a system of identification still in use. About 25,000 Fraunhofer lines are now known to exist in the solar spectrum, between the wavelengths of 2,950 and 10,000 angstroms. (One angstrom equals 10-8 cm.)