Why is the ninth month called September?
spectroscopy spec·tros·co·py (spěk-trŏs'kə-pē)
The study of spectra, especially experimental observation of optical spectra.
The analysis of spectra, especially light or mass spectra, to determine properties of their source. ◇ In light or optical spectroscopy, the spectrum of a light source is analyzed through a spectroscope to determine atomic composition of a substance. In astronomy, phenomena such as red shift can also be analyzed. ◇ In mass spectroscopy, a spectroscope is used to determine the composition of ions or charged molecules in a sample. Spectroscopy is also called spectrography. See also atomic spectrum, spectroscope.
The branch of science devoted to discovering the chemical composition of materials by looking at the light (and other kinds of electromagnetic radiation) they emit. Scientists use spectroscopy to determine the nature of distant stars and galaxies as well as to identify and monitor the production of products in factories.