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: NGC 7380 in Cepheus is an impressive large emission nebula which also happens to host a stellar nursery. Just north of the central portion of the nebula in the image below is home to a young open cluster which helps illuminate the surrounding hydrogen gas along with other neighbouring stars in this rich part of the sky. The open cluster measures 12 arc-minutes in diameter is loosely populated with approximately 50 to 100 member stars. This impressive emission nebula is quite large and slightly elongated and approaches the size of the full moon in apparent diameter. It lies at a distance of 7,200 to 11,500 light-years away (depending on the source) and spans 23-24 light-years across. First discovered by William Herschel's sister (Caroline) in 1787, this celestial gem is well-placed during fall and winter when it is reaches its greatest altitude above the north celestial pole around midnight.