January 17, 2012: The Witch Head Nebula
The Witch Head Nebula is a reflection nebula (meaning it reflects light from a star close to it). It is linked to Rigel located in the constellation Orion. Rigel provides the light primarily reflected by this nebula. The blue color is partly caused by Rigel's color but also the blue color is due to the fact that the particles of dust reflect blue light more efficiently than red light. For the same reason, Earth's sky appears blue. The Witch Head nebula is roughly 1000 light-years away.