Also found in: Dictionary, Thesaurus, Wikipedia.
Related to Diffuse Nebulas: Dark nebula, emission nebula, planetary nebula, Reflection nebula, Orion Nebula, Supernova remnants
nebulous objects, belonging to the class of galactic nebulas. They are distinguished as follows: bright emission diffuse nebulas (their spectrum basically consists of emission lines); bright reflection diffuse nebulas; and dark nebulas, visible as dark patches against the bright background of the Milky Way. Diffuse nebulas are also observed in other galaxies.