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Explore the significance of Fraunhofer's mapping of dark spectral lines, their identification with alphabetic labels, and the absorption patterns in the Sun's spectrum, including sodium D lines and their relevance to street lamps. Discover the pioneering work of Fraunhofer in astrophysics seen through commemorative stamps.
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Atoms in the cooler gas mantle around the Sun absorb the background hotter radiation we see at specific wavelengths
Fraunhofer’s original drawn lines overlayed on the visible spectrum - NB with red to the left (modern convention is blue to the left)
G F E D C B A 500 600 700 nm 400 Fraunhofer mapped out the puzzling dark lines in the solar spectrum labelling them A B C D… from the red end
3P3/2 Sodium D Lines 3P1/2 589.0 nm 589.6 nm 2S1/2 0.597 nm
Fraunhofer Absorption Lines in the Sun’s Spectrum Na D lines Orange street lamps contain sodium
3P3/2 Sodium D Lines 3P1/2 589.0 nm 589.6 nm 2S1/2 0.597 nm
G F E D C B 500 600 700 nm 400
Noting that the solar spectrum was crossed by "innumerable" dark lines, Fraunhofer mapped their relative positions with precision. He developed an alphabetic system for labeling selected reference lines, assigning A to a line near the red end of the spectrum, D to the pair of dark lines associated with the bright orange streak he had observed in flame spectra, H to a line near the end of the visible violet, and I to a line in the ultraviolet. Fraunhofer's lines puzzled practitioners and theorists alike for over four decades after the publication of his spectral maps.
Noting that the solar spectrum was crossed by "innumerable" dark lines, Fraunhofer mapped their relative positions with precision. He developed an alphabetic system for labeling selected reference lines, assigning A to a line near the red end of the spectrum, D to the pair of dark lines associated with the bright orange streak he had observed in flame spectra, H to a line near the end of the visible violet, and I to a line in the ultraviolet. Fraunhofer's lines puzzled practitioners and theorists alike for over four decades after the publication of his spectral maps.
Fraunhofer Absorption Lines in the Sun’s Spectrum Na D lines Orange street lamps contain sodium Harry Kroto 2004
