Credits: NASA / STScI Digitized Sky Survey / Noel Carboni

As the name implies, this reflection nebula associated with the star Rigel looks suspiciously like a fairytale crone.
Formally known as IC 2118 in the constellation Orion, the Witch Head Nebula glows primarily by light reflected from the star.
The color of this very blue nebula is caused not only by blue color of its star, but also because the dust grains reflect blue light more efficiently than red.
A similar physical process causes Earth's daytime sky to appear blue.

Facts about IC2118 by Keith Turnecliff

The Witch Head Nebula (IC 2118) is an extremely faint reflection nebula located in the Eridanus (The River) Constellation.
Astronomers are still learning about this molecular cloud, but research indicates that the wind-swept appearance may have formed from stellar wind of nearby, highly luminous stars.