Describe the difference between a reflection nebula, an emission nebula, and a dark nebula and what spectra would they show, if any.
A reflection nebula is when starlight is scattered in a dusty nebula. It reflects the absorption spectrum of the star. An emission nebula is prouced when a hot star excites the gas to produce an emission spectrum. A dark nebula is a dense cloud of dust and gas that obstructs the view of more distant stars. It produces no spectra