Beginning in 1862, Huggins used a spectroscope to probe the chemical nature of stars and nebulae. Since then, spectrometry has been the tool for the observational investigation of almost every important astrophysical question, through direct or indirect measurement of temperature, chemical abundance, gas pressure, wavelength shift, and magnetic field strength. The book by Hearnshaw (1986), from which the above quotes were taken, provides a history of astronomical spectroscopy prior to 1965. Since 1965, the importance of spectroscopy has only increased. This chapter introduces some basic ideas about spectrometer design and use. Kitchin (1995, 2009) and Schroeder (1987) give a more complete and advanced treatment, and Hearnshaw (2009) provides a history of the actual instruments.

Literally, a spectroscope is an instrument to look through visually, a spectrometer measures a spectrum in some fashion, and a spectrograph records the spectrum. Astronomers are sometimes particular about such distinctions, but very often use the terms interchangeably.