Spectroscopy in a new light

Scientific spectroscopy really began in Uppsala, Sweden, where Anders Angstrom in 1853 showed that some of the lines in the spectrum of an electric spark come from the metal electrodes and others from the gas between them. Even earlier, Joseph Fraunhofer had charted the dark lines in the spectrum of the sun, and had measured their wavelengths. But it was Angstrom who first identified some of these lines as corresponding to bright lines emitted by particular substances in the spark. Most importantly, he showed the red line of hydrogen, now known as H. In subsequent years, Angstrom found several more visible lines from hydrogen, and measured their wavelengths accurately. When W. Huggins and H. W. Vogel succeeded in photographing the spectra of stars in 1880, they found that these visible lines were part of a longer series extending into the ultraviolet. J. J. Balmer 5 in 1885 was able to reproduce the wavelengths of these lines by a formula, which we might write as