The Pipe Dark Nebula . ... Credit Copyright: Jerry Lodriguss Explanation: The dark nebula predominant at the lower left of the above photograph is known as the Pipe Nebula . The dark clouds, suggestively shaped like smoke rising from a pipe, are caused by absorption of background starlight by dust. ... Many types of nebula are highlighted here: the red are emission nebula, the blue are reflection nebula, and the dark are absorption nebula. ... NASA Web Site Statements, Warnings, and Disclaimers . ...