bright nebula

The term bright nebula indicates a cloud (i.e., nebula) that emits or reflects visible light, i.e., an emission nebula (an HII region, planetary nebula, or visible supernova remnant) or a reflection nebula. The converse is termed a dark nebula.

Note there has been some variation in terminology, as to exactly which types of objects would be termed emission nebulae or bright nebulae, e.g., wither planetary nebulae would be included.