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A technique used by astronomers that allows them to determine the properties, such as composition, temperature, and motion through space, of celestial objects by analyzing the spectra of celestial objects. For example, because each atomic element absorbs and emits light in a unique set of wavelengths, the astronomer can sift through the spectrum of a star and determine what elements are present in the star’s atmosphere. From the shapes and depths of spectral lines, the astronomer can calculate fundamental qualities of a star, such as how fast the gases churn through the stellar atmosphere or the star’s effective temperature. An astronomer may also be interested in correlations between the abundances of certain elements and the physical behavior of the star, the age of the star, or the abundances of other elements. For instance, compared with the Sun, stars with low amounts of iron are also low in almost every other element with respect to hydrogen. Spectroscopy is performed by astronomers with instruments called spectrographs.

Radio Programs

Moon and Spica Plotting the motions of a bright star June 19, 2021

Metallic Skies Rare metals in distant skies January 21, 2021

51 Pegasi Setting off a Gold Rush December 6, 2019

Capella Measuring a double binary star system October 16, 2019

Moon and Regulus Checking the barcode of a star June 8, 2019

More Capella Seeing a star in a different light November 26, 2017

Moon and Spica Learning about a bright stellar duo June 4, 2017

Featured Images

Backlit Planet September 16, 2016