Witch Head Nebula : IC-2118

The star Rigel is close to the Witch Head Nebula, and is one source of the glowing blue. The nebula pretty much reflects light from Rigel. Also known as IC-2118 in the Orion constellation, it mostly glows blue, because dust particles reflect blue light better than red. A similar process that makes the Earth's sky look blue gives the Witch Head Nebula its color.

Photo : NASA STScI Noel Carboni