The Veil Nebula, also known as the Cygnus Loop or the Witch's Broom Nebula, is a large, relatively faint supernova remnant in the constellation Cygnus. When finely resolved, some parts of the image appear to be rope like filaments. The standard explanation is that the shock waves are so thin, less than one part in 50,000 of the radius, that the shell is only visible when viewed exactly edge-on, giving the shell the appearance of a filament. Undulations in the surface of the shell lead to multiple filamentary images, which appear to be intertwined. [Wikipedia]