Generic term for non-glowing nebula. These are concentrations of dust only visible if they block out the light of stars that lie behind them. Many dark nebula have already been claimed by hider and cloudharvesting civilizations.
Great Rift, Great River - Text by M. Alan Kazlev Series of dark, obscuring dust clouds in the Milky Way Galaxy. As seen from the Inner Sphere, These clouds stretch from the constellation Sagittarius to the constellation Cygnus.