Spectroscopic Astronomy

Abstract

THE science of celestial chemistry and physics was brought into existence in 1859, when Kirchhoff's famous experiment on the reversal of spectral lines furnished the key to the interpretation of the dark lines of the solar spectrum, and thence to the determination of the composition of the sun and stars. The new science developed with extraordinary rapidity, and within ten years the spectra of all the different classes of celestial bodies had been carefully observed. The gaseous nature of some of the nebulae had been discovered by Huggins, and a spectroscopic classification of stars had been made on such sure foundations by Secchi that it still survives as one of the most convenient modes of describing the main features of stellar spectra. The memorable discovery by Lockyer and Janssen of the method of observing solar prominences withouF waiting for an eclipse of the sun was also made during this fruitful period, and the possible determination of the radial motions of stars by displacements of the spectral lines had been put to a practical test by Huggins. The demonstration that the immensel distant celestial bodies were composed, in part at least, of the same kinds of matter as the earth may well take rank among the greatest triumphs of science.