Nebulae (the plural of Nebula) are among the most beautiful targets for the astrophotographer. In the largest telescopes, nebulae reveal little of their color and structure to the human eye, but to the camera - Ooh, la la! Nebulae come in two primary categories. The first is "Emission", which contain gas that glows of it's own accord because of nearby stellar radiation. "Reflection" nebula are mostly inert gas, and reflect light, usually from a nearby bright star.