What is a Reflection Nebula?

These nebulae give reflected light from nearby broadband emitters light stars as the light is reflected off interstellar dust particles. They are usually blue for the same reason our sky is blue; scattering of broadband light is more efficient at blue wavelengths.

Examples of reflection nebula include the Iris nebula (NGC 7023), the Pleiades (M45) and the Witch Head nebula (IC2118).