Dark nebulae Barnard 92 and Barnard 93 are located on the northern edge of M24, the small Sagittarius star cloud. B93 is at left, and B92, at right. Dark Nebulae are clouds of dust and dark matter in space that are opaque, or nearly so, that obscure the stars behind them. These dark nebulae get their name from pioneer astrophotographer Edwin Emerson Barnard, who cataloged many of them photographically, publishing a list in a paper in 1919 in the Astrophysical Journal, On the Dark Markings of the Sky with a Catalogue of 182 such Objects.