Nebulae represent clouds of gas and dust which appear as hazy or fuzzy objects when viewed through a telescope and are characterized as one of four types (emission, planetary, reflection or dark). Emission nebulae, such as the Lagoon nebula (M8), simply glow, for example, with a stunning shade of red. Planetary nebulae appear as small greenish disks through a telescope, thus emulating the planets Uranus and Neptune, as a result of gas masses being thrown off by dying stars (ex. M27, Dumbbell nebula) or represent supernova remnants (ex. M1, Crab nebula). In contrast, reflection nebulae are characterized with gas surrounding young stars which reflect the stellar light (ex. M45, Pleiades) and, thus, yield beautiful images of nebulosity. Finally, dark nebulae are detectable and studied only using parts other than the visible spectrum and are believed to be associated with the formation of stars (ex. M16 in Serpens).

Note: The Elephant Trunk Nebula (IC 1396A) in Cepheus is part of the larger IC 1396 complex which spans a large area of the sky measuring 170 by 140 arc-minutes and is one of the brightest emission nebulae with a magnitude of 3.5. The western portion of IC 1396 contains the Elephant Trunk Nebula (IC 1396A) which is characterized with H-II emissions, dark lanes and globules as well as a small reflection nebula (see small blue patch near the right end of the trunk). The IC 1396 complex is technically a star cluster (aka Cr 439, Trumpler 37) owing to the presence of a developing open but loose cluster at the heart of this rich nebulosity and which is evident in the image below. This open star cluster is comprised of 50-100 member stars which vary in brightness spanning an area of approximately 50' in diameter and which are not very well detached from the background sky. This stellar nursery lies at a distance of 2,720 light-years away and is located a few degrees north of the midpoint between Alderamin (α-Cep, mag 2.43) and ζ-Cep (mag 3.34) and includes the well-known and bright carbon star μ-Cep (Herschel's Garnet Star, B-V=+2.317).