Astronomers and astrophysicists regularly make use of the theoretical tools of special relativity to interpret and analyze light. For instance, astronomers rely on Doppler shift measurements to calculate the motions of stars and galaxies. Special Relativity is the concept tool of the calculation, relating a wavelength shift to the velocity of the source. Usually, a CCD camera records the spectrum , transmits the image to a computer that writes the data to a hard drive or tape. The astronomer is free to look at the spectrum on the computer monitor, then analyze the image.
Astronomers seek the recipe of stars, galaxies, and other celestial objects through spectroscopy.
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. The spectrum is evidence of whatever is glowing, or radiating light. With spectroscopy astronomers relate the appearance of the spectrum to the physical processes inside the star. From the shapes and depths of spectral lines, the astronomer can calculate fundamental qualities of a star, like how fast the gases churn through the stellar atmosphere, or the star's effective temperature . For instance, compared with the Sun, stars with low amounts of iron are also low in almost every other element with respect to hydrogen.