Chapter 1
?How the dark lines in the solar spectrum are formed
Leon Focault matched the lines produced by a sodium lamp with some of the dark lines in a solar spectrum in 1849. In 1857 Gustav Kirchoff and Robert Bunsen identified sodium in a solar spectrum. They found that a luminous solid or highly compressed hot gas could produce a continuous spectrum whilst a diffuse hot gas produced a spectrum with narrow bright lines on a black background.
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?-What do the dark lines in the solar spectrum represent
sodium and helium
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?Why the spectroscopy is a key tool in astronomy
By obtaining and analyzing the spectrum from a distant object, astronomers can identify what type of object it is and determine a wealth of characteristics for the object. These include its effective temperature, how fast it is rotating and whether it is moving towards or away from us, how large and dense it is and what it is made of. Within the last decade planets beyond our Solar System have been discovered via their effect on the parent star's spectrum.