A nebula is an interstellar cloud of matter, comprised usually (and mostly) of dust, hydrogen gases (or, in rarer cases, other types of gases) and plasma. A nebula is the first stage of star development.
Starfleet starships used nebulae to their strategic advantage in conflicts with hostile starships, since sensors and other critical shipwide systems could be affected by, or perform poorly in, some nebulae.
In 2285, Captain James T. Kirk took a damaged USS Enterprise into the Mutara Nebula to buy more time against Khan Noonien Singh and his crew aboard the hijacked USS Reliant. The Enterprise and Reliant battled in the Battle of the Mutara Nebula, with Khan and the Reliant losing. Khan detonated the Genesis Device, consolidating the Mutara Nebula to create a new system; the Enterprise escaped thanks to Captain Spock's sacrifice. (Star Trek II: The Wrath of Khan)
USS Excelsior Captain Hikaru Sulu masked his ship's approach to Qo'noS by taking it through the Azure Nebula in 2293. in the nebula, they encountered a Klingon bird-of-prey, commanded by Captain Kang. Sulu ordered the volatile sirillium gas be ignited in an attempt to evade the Klingons. It succeeded, but Sulu never entered the event in the ship's log. (VOY: "Flashback")
In 2366, the USS Enterprise-D hid in the Paulson Nebula as a tactic to delay the Borg cube from proceeding to Earth. The Borg responded with magnetometric-guided charges to force the Enterprise out of hiding. (TNG: "Best of Both Worlds")
Also in that same year, the USS Dragon-A investigated a distress signal emanating from the Marauder nebula. Upon closer investigation, they discovered the USS Excelsior stuck in the nebula, and both ships were pulled into a temporal anomaly, sending them back to the 20th century mirror universe Earth. (Star Trek: Dragon: "Dimensional Exploration-Ghost Ship")
- Dark nebula
- Dark matter nebula
- Dichromatic nebula
- Emission nebula
- Inversion nebula
- Planetary nebula
- Protostellar nebula
- Reflection nebula
- Stellar nursery