Light from distant objects can tell us much about the object we are seeing. For example, the emission line spectrum of the Orion Nebula in a portion of the ultraviolet range $350$ to $400$ nm reveals four atoms whose lines are all quantum jumps from higher levels to the level $2$ quantum level. In other cases, we get a complicated spectrum such as the one we receive from the sun. This spectrum holds a number of clues about the sun. If we observe the intensity of the spectrum of light from the sun, we would see which correspond to emission lines, $$ which correspond to absorption lines, and

$$ which corresponds to complex bands from various states of matter. The complex spectrum can reveal aspects such as rotational and vibrational motions of molecules, as well as