... Although glowing like an emission nebula, the origin of the bubble, known as Barnard's Loop , is currently unknown. Progenitor hypotheses include the wind s from bright Orion stars and the supernovas of stars long gone. ... Just to the right of the lowest star in Orion's belt is a slight indentation in an emission nebula that, when seen at higher magnification , resolves into the Horsehead Nebula . To the right of the belt stars is the bright, famous, and photogenic Orion Nebula . ...