Auguste Comte(1798-1857)Also founder of Sociology

One of the most influential philosophers of the first half of the nineteenth century. A prominent figure in Positivism which has as a central tenet that scientists should not waste their time or energy in attempts to answer unanswerable questions. He believed that stellar astronomy, as opposed to planetary astronomy was a useless exercise because we could never investigate the chemical composition of the stars.
In his Cours de philosophie positive (1830-42) he wrote

" ... to attain a true idea of the nature and composition of this science,
( astronomy) it is indispensable to set aside the vague definitions of it that are still being given, and to mark the boundaries of the positive knowledge that we are able to gain of the stars.
Of the three senses that reveal the existence of distant bodies ,  that of sight is clearly the only one applicable to the celestial bodies.  Any research that is irreducible to actual visual observation is necessarily excluded in regards to the stars,... we can never by any means investigate their chemical composition... the positive knowledge we can have of the stars is limited  solely to their geometrical and mechanical properties.

"It is therefore necessary that we separate more completely than is commonly done the solar from the universal point of view, the idea of the world from that of the universe: the first is the highest we can actually attain , and it is also the only one that truly interests us."
 

In his book Traite philosophique d'astronomie populaire ( 1844) he wrote

" in the eyes of those for whom science consists of real laws and not of incoherent facts, the second( stellar astronomy) exists only in name, and the first( solar astronomy) alone constitutes the true astronomy; and I am not afraid to assert that it will always be so.
 

Brief Chronology of Spectroscopy  (reference text)
 

• 1666    Isaac Newton  discovers the optical spectrum
• 1800   William Herschel discovers that energy exist in the spectrum beyond the visible in the infra red region
• 1801  J. W. Ritter discovers ultra violet rays and shows they produce chemical effects
• 1802  W. H. Wollaston discovers 7 dark lines in the solar spectrum
• 1827  John Herschel color effects in spectra of flames impregnated with various metallic salts
• 1828   Josef Fraunhofer had already published papers describing over 500 dark lines in the solar spectrum, showed that the lights from the planets and moon exhibited the same pattern of lines, found the spectra of some stars differed from the sun, discussed bright line spectra in relation to dark line spectra, developed the diffraction grating.
• 1832   David Brewster discovers that a a dark line spectrum is produced when a continuous spectrum passes through a gas
• 1847   John Draper discovers that an ignited body yields a continuous spectrum and an ignited gas yields a broken spectrum. Also finds that as the temperature of a body increases it gives off light of higher frequency.
• 1859   Wilhelm Bunsen and Gustav Kirchhoff establish spectrum analysis as a reliable tool for investigating chemical composition
• 1859   Gustav Kirchoff publishes a study of the chemical composition of the sun based on spectrum analysis.
• 1861   Kirchoff and Bunsen discover two new chemical elements, cesium and rubidium by spectroscopic techniques. Later many more new elements were discovered using this technique.
• 1864   William Huggins  using a spectroscope attached to a telescope establishes the gaseous nature of nebulae.
• 1864  G. B. Donati discovers bright spectral lines in comets
• 1868 Huggins discovers the shift in frequency predicted by  Doppler
• which enables astronomers to measure velocities of objects along the line of sight.
• 1868  Angelo Secchi produced a stellar spectral classification with four categories.
• 1868  Jules Janssen and J. Norman Lockyer discover helium first in the sun's spectrum
• 1872 Henry Draper makes the first photograph of a stellar spectrum.
• 1890 Publication of the first Henry Draper Catalogue of spectra of 10,000 stars divided into seven categories.
• 1895 Henry Rowland, using a diffraction grating records a solar spectrum of 20,000 lines.

Spectroscopic Techniques

Modern studies of the universe have a wide range of techniques available which extend well beyond the limits of optical spectroscopy. In fact, these techniques extend beyond the electromagnetic spectrum.

• optical astronomy
• microwave astronomy
• radio astronomy
• infra red astronomy
• ultra violet astronomy
• x-ray astronomy
• gamma ray astronomy
• neutrino astronomy
• cosmic ray studies
• Gravitational waves detection