A planetary nebula was a type of emission nebula, created by expelled matter of a star reaching the end of its life. M2-9 was such a nebula. The crew of Enterprise NX-01 surveyed a planetary nebula in 2151, at which time they detected a Vulcan survey ship apparently shadowing their activities. This happened three weeks before Enterprise encountered the Suurok-class Ti'Mur. (ENT: "Breaking the Ice") In the writers' second draft script of "Breaking the Ice", this nebula was referred to as simply a nebula whose type was unspecified, though it was also mentioned as being "off the Merrium System."