Reflection Nebulae

A reflection nebulae is completely different from an emission nebulae. It is a cloud of dust and gas that reflects the light energy from a nearby star or group of stars rather than emitting their own light. It glows as the dust in it reflects the light of these nearby stars. These nebulae are frequently bluish in color because blue light is more efficiently reflected than red light.
When light passes by a particle of dust, the blue color in that light is scattered, while the rest of the colors in the light are allowed to travel undisturbed. This blue light travels around the cloud bouncing off of dust particle after dust particle until it eventually escapes the cloud and reaches our eyes.
A reflection nebula surrounds the Pleiades Cluster. The Trifid Nebula (M20) in Sagittarius is another good example of a reflection nebula.

Pleiades Cluster

The Trifid Nebula (M20)