This nebula was given the name "Witch Head Nebula" by American astronomer Frank E. Ross. The nebula was discovered by German astronomer Max Wolf. This is a reflection nebula that is illuminated by the star Rigel in Orion. Rigel is 2.6 degrees to the east of the nebula and outside the field of view shown in this image. Fine dust particles in the nebula scatter light from the star and reflect sufficient light so that we can see the cloud of interstellar dust. Rigel is a blue supergiant star, and is able to illuminate the nebula from a distance of 40 light-years away. If Rigel had not been close enough to illuminate the dust grains in this cloud, it would have been a dark nebula instead. Reflection nebulae typically appear blue, because dust grains reflect blue light more efficiently than red light. In contrast, an emission nebula appears red, because the nebula glows as a result of hydrogen gas that has been excited by ultraviolet radiation. The Witch Head Nebula is located about 1000 light-years from Earth.
This is an RGB color composite CCD image taken with a Takahashi Epsilon 180ED telescope using an SBIG STL-11000M CCD. The image was taken at the University of Arizona Mount Lemmon SkyCenter.
IC 2118
Constellation: Eridanus
RA: 05h 04m 09s Dec: -07d 15' 00" (J2000)
November 22, 2009
Image by Sid Leach
Mount Lemmon, Arizona
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