This nebula shaped like a witch head is associated with the bright star Rigel in the constellation Orion. The Witch Head Nebula glows primarily by light reflected from bright star Rigel, located just off the upper right edge of the full image shown in the link below. Fine dust in the nebula reflects the light. The blue color is caused not only by Rigel's blue color but because the dust grains reflect blue light more efficiently than red.

This is a very large nebula. This is only a partial view. It only received 40 minutes total exposure so much more exposure time and a different orientation of the camera would be required to see the entire nebula. To see the whole nebula see:

http://apod.nasa.gov/apod/image/0612/ic2118_dss_big.jpg