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 expansive emission nebula NGC 7000, more commonly referred to as the North America nebula owing to its characteristic shape, is a large area of nebulosity lying to the immediate southeast of Deneb (α-Cyg) and is equivalent to about twelve full moons in apparent area. NGC 7000 is active in star formation and includes three clusters, namely NGC 6989 to the northwest, NGC 6996 to the north and NGC 6997 to the west. NGC 7000 lies at a distance of 2,200 light-years away and is estimated to span 100 light-years across. To its right and separated by a dark absorption cloud is the also expansive Pelican emission nebula (IC 5067 and IC 5070). Similarly, to its bottom right is the smaller emission nebula IC 5068. The North America nebula is best observed using low magnifications (50-100x) during mid-summer preferably under dark skies as it approaches zenith around midnight and using either a UHC or O-III filter. NGC 7000 was discovered by William Herschel in 1786.

The section depicted by the "Gulf of Mexico" in the image below is more commonly referred to as "The Great Cygnus Rift" and represents the starting point of dust clouds which continue onto Aquila and Ophiuchus and bisect our Milky Way in half when viewed edge-on, for the dust obscures starlight and yields the observer darkened lanes or nebulae stretching for one thousand light-years across. These dark nebulae expand in size as one moves away from Cygnus and progresses southwards towards Aquila and Ophiuchus. The Great Cygnus Rift, also known as the Northern Coalsack, is also an area of very active star formation and only two thousand light-years away from the two other major star formation areas in the general vicinity, namely NGC 7000 (North America Nebula) and IC 5070 (Pelican Nebula).