The Horsehead Nebula (cataloged as B 33) is a dark nebula situated next to the star Alnitak (ζ Ori) in Orion's Belt. It is made up of interstellar dust that, blocking the light emitted from the hot gas visible in the background, generated the silhouette of a horse.
On the left side of the image, is also visible the Flame Nebula (NGC 2024).
B 33 is about 1500 l.y. away from us.