IC 2118, The Witch Head Nebula

IC 2118 is a sprawling reflection nebula, famously known as the Witch Head Nebula. Its eerie, profile-like appearance is illuminated not by stars within the cloud itself, but by the intense radiation of the supergiant star Rigel, which sits just outside the frame in neighboring Orion. The nebula is composed of incredibly fine interstellar dust grains that are particularly effective at scattering shorter wavelengths of light; this "Rayleigh scattering"—the same physical process that makes the Earth's sky appear blue—gives the Witch Head its distinctive and ghostly azure hue. While primarily a reflection of Rigel’s brilliance, internal radio observations have revealed dense molecular clouds and signs of ongoing star formation, proving that this celestial "specter" is also a productive stellar nursery.