History

Spectroscopy in astronomy

Spectroscopy in astronomy

The spectroscopy It is the study of the interaction that exists between electromagnetic radiation and matter. For its part, astronomical spectroscopy is this same technique applied to astronomy. Where appropriate, the object of study is the spectrum of electromagnetic radiation that emanates from stars and other celestial objects.

Astronomical spectroscopy is used to know many of the properties of the farthest stars and galaxies. For example, its chemical composition and movement, and to find out the Doppler effect is used.

Origin of astronomical spectroscopy

The use of astronomical spectroscopy had its origin in the initial studies that Isaac Newton carried out to decompose the sunlight. He used a prism for it, and got a rainbow of color and probably some absorption lines. These were dark bands that appear in the solar spectrum, and were first described, in 1817, by the German astronomer Joseph von Fraunhofer.

Today it is known that almost all star spectra have these two characteristics present in the solar spectrum; on the one hand, the emission in all wavelengths of the optical spectrum (the continuum); and, on the other, several overlapping absorption lines.

The Italian astronomer Angelo Secchi made a classification of the stars according to their spectral types. For this, it was based on the number and strength of the absorption lines of its spectrum, which determine the chemical composition of a star. Currently, stellar observation by spectroscopy is used to know stellar properties, such as distance, age, luminosity or mass loss rate.

Other uses of astronomical spectroscopy

In addition to the stars, astronomical spectroscopy can also be applied to the observation and study of other celestial bodies, such as nebulae, galaxies, quasars, planets and asteroids or comets. In the case of galaxies, galactic spectroscopy has proved vital to make many fundamental discoveries. Among others, the discovery of the American astronomer Edwin Hubble in the 1920s.

Hubble observed that, apart from the nearest galaxies (known as the Local Group), all galaxies move away from Earth. He found that the farther a galaxy is, the faster it moves away. This discovery was the first foothold of the Big Bang Theory, according to which the Universe was created in a single point.

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