Rayleigh scattering is the spectroscopic phenomenon that makes the sky look blue.
Spectroscopic studies were central to the development of quantum mechanics and included:
Max Planck's explanation of blackbody radiation
Albert Einstein's explanation of the photoelectric effect and
Niels Bohr's explanation of atomic structure.
Spectroscopy is used in physical and analytical chemistry because atoms and molecules and combinations of both
all have a unique signature.
