1. Synonyms for Ambiguities include ambiguousnesses, enigmata, vaguenesses, abstrusenesses, inscrutability, inscrutableness, murkinesses, mysteriousnesses, nebulosities

2. Its main ring contains knots of nebulosity, which have now been detected in many nearby planetaries.

3. In the late 1970s the use of modern detectors (such as CCD) allowed observers to probe with better accuracy the nature of the nebulosity.

4. As it is both bright and moving through a region of nebulosity, Rigel lights up several dust clouds in its vicinity, most notably the 5°–long IC 2118 (the Witch Head Nebula), located at an angular separation of 2.5° from the star.