Nebula Nova Cygni Turns On . ... In 1992, a white dwarf star toward the constellation of Cygnus blew off its outer layers in a classical nova explosion: an event called Nova Cygni 1992 . Light flooded the local interstellar neighborhood , illuminated this existing gas cloud, excited the existing hydrogen , and hence caused the red emission. ... Eventually, light from the nova shell will fade, and this nebula will again become invisible! ... NASA Web Site Statements, Warnings, and Disclaimers . ...