A reflection nebula is a cloud of interstellar dust that reflects the light of nearby stars. These nebulae are made up of gas and dust, and appear blue because the dust particles in the nebula scatter the blue light more efficiently than red light.
Reflection nebulae are formed when the light from nearby stars is reflected off the dust particles in the nebula. The dust particles scatter the light, creating a beautiful blue glow that we see as a reflection nebula.