One of the most recognizable star patterns in the northern sky, Cygnus the Swan invites observers to embark on a journey through space and time, narrated by its stellar points and the myths that envelop them. Cygnus’ graceful array stretches across a vast portion of the heavens, making it one of the largest constellations and certainly one of the most prominent in the summer sky. Occupying an area of over 800 square degrees, Cygnus constellation stands as the 16th largest constellation, making it a dominant presence on the Northern Hemisphere’s summer nights.
Situated on the plane of the Milky Way, Cygnus constellation boasts a rich tapestry of stars, nebulae, and other celestial wonders. The constellation lies nestled between Cepheus, Lyra, Pegasus, and Draco, its stars shimmering with distinct brightness against the dense backdrop of our galaxy. This positioning provides not only a celestial spectacle for casual stargazers but also a rich hunting ground for astronomers and astrophotographers.
The constellation Cygnus is home to a number of significant historical astronomical discoveries and exciting celestial objects. Among its claims to fame are:
- 61 Cygni is one of the first stars to have its distance or motion measured
- Cygnus X-1, the first black hole discovered
- The Fireworks Galaxy is home to more frequent supernovae than any other galaxy yet observed
- NML Cygni, one of the largest and brightest stars known, is able to swallow everything in our Solar System out to Saturn if it were placed where the Sun is
- The Veil Nebula, a remnant of a supernova likely seen by humans at the end of the last Ice Age
- Kepler-186f and Kepler-442b are some of the most Earth-like exoplanets currently known to us
The Swan’s legacy extends to humanity’s ventures into the cosmos, too. The Cygnus spacecraft, which regularly resupplies the International Space Station, is named after the constellation. Essentially a large, disposable metal container with maneuvering capabilities, the adaptable Cygnus spacecraft derivatives will be utilized as part of NASA’s Artemis program to return humans to the Moon. The Japanese Kounotori or HTV spacecraft, which filled a similar role to Cygnus in resupplying the ISS, is also named as a reference to a white-feathered waterfowl, though technically the name translates to “stork” rather than “swan”.
Cygnus the Swan in Mythology
In Greek mythology, Cygnus constellation is often associated with the tragic story of Zeus and Leda. Zeus, the king of the gods, had a penchant for taking on different forms to woo mortals and demigods. In the tale of Leda, Zeus transformed himself into a beautiful swan to seduce her. Leda later gave birth to two eggs, one of which hatched Helen of Troy (the cause of the Trojan War) and the Dioscuri twins, Castor and Pollux. Another version of the story recounts that the offspring were Clytemnestra and Castor, with the other egg producing Helen and Pollux.
Another narrative links Cygnus to Orpheus, the legendary musician and poet. After being murdered by the Maenads (followers of Dionysus), Orpheus was thrown into the river, and his lifeless lyre was placed next to him. Zeus, moved by the tragic end of the great musician, decided to commemorate him by transforming the lyre into the Lyra constellation and Orpheus himself into a swan, becoming the constellation Cygnus, forever to remain near his beloved instrument in the sky.
Yet another version of the constellation Cygnus story connects the Swan with the Symphalian birds, carnivorous swamp-dwelling creatures that the legendary demigod and strongman Hercules had to slay as penance to the gods for his crimes. The constellation of Hercules happens to be next to Cygnus in the sky, which may explain the rather shaky inspiration for this myth.
The ancient Romans took many tales from the Greeks and adopted them as their own, as well as adding new twists. They associated Cygnus with the legend of Phaethon (or Phaeton), the son of the sun god Helios (later Sol Invictus), who stole his father’s chariot, which pulled the Sun along the sky each day. Like any inexperienced teen driver, Phaethon had no idea what he was doing, and Jupiter (the Roman equivalent to Zeus) had to zap him with a lightning bolt to avoid a cosmic traffic incident. As compensation, Jupiter turned him into a swan and placed him in the sky. Jupiter/Zeus has a habit of doing this in mythology; Ursa Major and Ursa Minor are also depicted as having been placed amongst the stars after an incident involving the thunder god.
While Greco-Roman mythology is rich with tales about Cygnus, the constellation has also been interpreted as a bird in various other cultures, such as the North American Indigenous Peoples, who saw it as a condor or an eagle. In Chinese astronomy, the main stars of Cygnus are incorporated into the “Northern Cross” asterism, which is part of the larger Summer Triangle. The Chinese knew it as 天津四 (the Fourth Star of the Celestial Ford), which is an asterism that helped locate the north celestial pole and served as a navigation reference.
Where is the Cygnus Constellation in the Sky?
Given its prominence and unique shape, it’s relatively straightforward to identify Cygnus constellation, but here are some steps you can use to locate the constellation if you need help:
How to Locate Cygnus Constellation
- Time and Season: The best time to observe Cygnus is during the summer and early fall, when it rides high in the northern hemisphere’s sky. However, its noticeable presence means it’s visible from late spring to winter in most northern latitudes.
- Locate the Summer Triangle: Begin by identifying the Summer Triangle, an asterism made up of three of the brightest blue stars from three different constellations: Deneb in Cygnus, Vega in Lyra, and Altair in Aquila. This large, nearly equilateral triangle is a beacon in the summer sky and acts as a perfect starting point.
- Identify Deneb: Of the three stars in the Summer Triangle, Deneb is the one that appears furthest north and is the dimmest of the trio (though it’s still one of the brightest stars in the sky). This luminary acts as the tail of the Swan.
- Trace the Cross: From Deneb, scan the sky for a cross-like pattern. This represents the body and wings of the Swan. Cygnus is often referred to as the “Northern Cross” due to its distinctive shape. Starting from Deneb, you can trace the body down to Albireo, a beautiful double star that represents the Swan’s beak. Perpendicular to this line and almost equidistant from the body, you can find two stars on either side, which form the wings.
- Milky Way Backdrop: Another advantage is that Cygnus is situated against the backdrop of the Milky Way, our galaxy’s dense band of stars. This provides a magnificent celestial scene, especially from locations with minimal light pollution. The dark rifts of the Milky Way and the bright areas, such as the Cygnus Star Cloud, should make it easy to identify Cygnus if your sky is free of significant city glow.
- Using a Star Map: If you’re still unsure, a star map or a stargazing app can come in handy. These tools can provide real-time charts of the night sky, making it even easier to pinpoint Cygnus.
Things to See in Cygnus
Bright Stars in Cygnus
As the brightest star in Cygnus constellation, Deneb, the top star of the Cross (but in fact the tail of the Swan) – serves as one of the vertices of the famous Summer Triangle, a prominent asterism visible in the summer skies of the Northern Hemisphere. The name Deneb is derived from the Arabic phrase Dhanab ad-Dajājah, which means “the hen’s tail”. This blue-white supergiant star, around 200 times the radius of our Sun, is one of the most luminous stars known, though exactly how luminous it is is still a matter of debate.
Deneb is the 19th brightest star in the night sky, with an apparent magnitude right around 1, and the star is situated around 2,620 light-years away from us. Deneb is currently the approximate northern pole star on Mars, equivalent to Polaris on Earth; the Red Planet’s axis points a few degrees away from the blue supergiant, while our own planet’s axial precession will make Deneb the pole star in about 10,000 years’ time. North of Deneb is Alderamin, the brightest star in neighboring Cepheus. Just south of Deneb lies Gamma Cygni, or Sadr, at magnitude 2.2.
Regarded as one of the most beautiful binary stars in the sky, Albireo (β Cygni), the bottom star of the Northern Cross, is often targeted by amateur astronomers. When observed through a telescope, it reveals two contrasting stars: a brighter golden-yellow primary and a fainter blue secondary, providing a stunning visual treat. The two are actually unassociated blue and orange giant stars several light-years apart.
Dotted nearby is Delta Cygni, a complex star system shining at magnitude 3. This intriguing system houses a visual binary companion and a close binary, amounting to at least three stars in close proximity. Meanwhile, ε Cygni, or Gienah, represents the wing of the swan, burning brightly at magnitude 2.5. Its orange hue is distinctive and complements the diverse palette of Cygnus stars.
Double Stars in Cygnus Constellation
One cannot discuss Cygnus constellation without mentioning 61 Cygni. This double star is relatively dim, at magnitudes 5.2 and 6.1 for its two components (combined around magnitude 5, or faintly visible with the naked eye from the suburbs or dark skies). However, 61 Cygni is significant. It was one of the first stars to have its parallax measured, indicating the duo’s closeness to Earth at approximately 11.4 light-years away and closing in – tens of thousands of years from now, they’ll be just 9 light-years out.
61 Cygni can easily be resolved into separate dots with a pair of 10x binoculars. The pair of orange dwarf stars are a little smaller than our Sun and are prime candidates to host habitable exoplanets, though none have been discovered around either star yet. 61 Cygni’s rapid motion can also be observed with amateur telescopes by sketching or photographing the stars’ positions over the years. The pair is moving by around 4 arc seconds per year, or about the apparent diameter of Uranus from our perspective, which adds up quite fast.
16 Cygni is a fascinating triple star system 69 light-years away from us, though at first glance, it appears as a binary of two yellowish stars shining each at around magnitude 6, separated by 40 arc seconds, or about the apparent diameter of Jupiter. This means even a pair of 10x binoculars will resolve the pair, much like 61 Cygni.
The brighter component of 16 Cygni, 16 Cygni B, has a confirmed exoplanet, making the system not only beautiful to observe but also significant in the study of extrasolar planets. 16 Cygni A and B are Sun-like stars, while C is a red dwarf orbiting close to A, only 73 AU (about twice the distance of the Sun and Neptune) away. Star B is about ten times further away as of the present, but no one is actually sure of its orbital path. 16 Cygni B’s planet, 16 Cygni Bb, is a gas giant about twice the mass of Jupiter orbiting in a highly elliptical path that takes it nearly as close as the orbit of Mercury and as far as the Asteroid Belt is from our star. This is likely due to the gravity of nearby 16 Cygni A & C. 16 Cygni Bb, of course, has also probably cleared out any other planets in its vicinity, ruining any hope of habitable worlds around B, while the orbital dynamics of A and C likely preclude a stable Earth-like world’s existence there.
Variable Stars in Cygnus Constellation
Among the constellation’s giants, NML Cygni stands out. The star is, unfortunately, masked entirely by a surrounding dust cloud and thus hovers around magnitude 17–18. This means it’s not observable with anything but the largest backyard instruments. However, this red hypergiant ranks among the galaxy’s most luminous and monstrous stars. NML Cygni is around 229,000 times brighter than the Sun, 40 times more massive, and would extend to around the orbit of Jupiter or Saturn if placed at the center of our Solar System. However, NML Cygni is remarkably cold for a star, at a temperature of just 2,500 Kelvin (2,225 degrees Celsius). This puts it close to the temperature of spectral class L, a category normally reserved for cool brown dwarfs or “failed stars”.
While not a variable star, another enigmatic feature in Cygnus is Cygnus X-1, an X-ray binary system. Not visible in the traditional sense like the aforementioned stars, this system, consisting of a blue supergiant and an unseen stellar-mass black hole, has been a cornerstone in the study of black holes, being one of the first to be identified as such. However, the 9th-magnitude blue giant star (HDE 226868) being swallowed by the black hole is easy to see with binoculars.
Exoplanets in Cygnus
Apart from 16 Cygni, the entire region of Cygnus constellation has been a focal point for the search for exoplanets, primarily due to the work of the Kepler Space Telescope. While pointed at Cygnus, Kepler discovered thousands of exoplanet candidates. Notable exoplanets within Cygnus include Kepler-22b, a super-Earth located in its star’s habitable zone; Kepler-186f, the first Earth-sized exoplanet discovered in a habitable zone, and Kepler-442b, another Earth-sized world considered one of the best candidates for hosting life. Kepler-22 is the brightest of the host stars of the three, at magnitude 11.7 (thus picked up by almost any small telescope); the other two are red dwarfs lying around 15th magnitude, thus requiring a 12” or larger telescope and dark skies to see.
Star Clusters in the Constellation Cygnus
Being home to one of the densest parts of the Milky Way, Cygnus lacks globular clusters but is home to a few impressive open star clusters. Messier 39 (M39) is among the most renowned open clusters in Cygnus. This relatively loose gathering, comprising about 30 stars, is a spectacle located approximately 800 light-years away from Earth. Given its age, estimated between 200 and 300 million years, M39 offers a mix of moderately aged stars, many of which dazzle with a blue-white brilliance.
Close to Sadr, another cluster, NGC 6910, makes its mark. Its pattern often draws comparisons to a “Rocking Horse” due to its unique configuration. The stars within this cluster are particularly young, with the entire formation believed to be less than 10 million years old. This relative youthfulness results in a brilliant display of luminous, young stars that stand out even amidst the rich star fields of Cygnus.
Located in the western part of Cygnus, Dolidze 9 contains several middle-aged stars and offers a stark contrast to the newer formations within the constellation. The cluster’s slightly older stars provide a look into the mid-stages of stellar evolution, bridging the gap between the newer and older inhabitants of Cygnus.
A bit to the east, the cluster Collinder 421 can be found. Though it’s less dense compared to some of the more prominent clusters in the sky, its stars are notably younger, revealing insights into the earlier stages of star birth and growth. The relative sparseness of this cluster allows for easier identification of individual stars, making it a favorite among amateur astronomers.
Further into the constellation, we encounter Berkley 90, another open cluster. It is notable for its compact nature and the sheer number of stars it houses. Its location near the Great Rift, a series of dark molecular dust clouds that split the Milky Way, gives it a dramatic backdrop, enhancing its visibility against the dark void.
Perhaps one of the most breathtaking features within Cygnus constellation is the Cygnus Star Cloud. This is not an open cluster in the traditional sense but rather a dense region of the Milky Way packed with countless stars. Its sheer density and brilliance make it a spectacular sight, especially when viewed through binoculars or a telescope. The star cloud serves as a testament to the rich stellar nursery that our galaxy hosts, with innumerable stars at various stages of their life cycles.
Constellation Cygnus Planetary Nebulae
Cygnus constellation also boasts an array of planetary nebulae. These fascinating celestial objects provide a glimpse into the final stages of a star’s life cycle, particularly those of stars similar in size to our Sun. As these stars exhaust their nuclear fuel, they shed their outer layers, forming glowing shells of ionized gas. This process results in the captivating structures we call planetary nebulae, named for their appearance in early telescopes: similar to the disk of Uranus at low power but have no actual association with planets. If you have a typical 8” Dobsonian or a larger and more capable telescope, all of the objects listed here are worthy sights at the eyepiece.
One of the most prominent planetary nebulae in Cygnus is NGC 6826, also known as the Blinking Planetary. It gets its unique moniker because of a visual effect experienced when observing it through a small (<6”) telescope: the central star becomes more apparent when viewed directly (with averted vision), but when an observer tries to focus on the surrounding nebula, the star seems to “blink” out. Larger telescopes provide a steadier image of both the central white dwarf star and the surrounding nebula, as well as adding a bit of color.
NGC 7027, also known as the Pink Pillow or Magic Carpet Nebula, is another intriguing planetary nebula in Cygnus. It’s relatively young and is undergoing rapid changes, making it an exciting subject of study for astronomers. Its high surface brightness and intricate, multi-layered structure of gas make it a fantastic sight, especially when observed with powerful telescopes. The nebula is mostly a deep blue through amateur telescopes, with high magnifications and 12” or larger telescopes revealing two separate lobes. A smaller telescope merely shows it as a bluish, ~14-arcsecond wide patch of light.
NGC 7026, the Burger Nebula, is a bluish planetary nebula 10 arcseconds in diameter. As the name suggests, the nebula appears as two bright patches (the bun) with a darker midsection. Even a 6” telescope vaguely reveals this morphology under good conditions, though a 10” or larger telescope is best.
Then there’s NGC 7008, often referred to as the Fetus Nebula. This planetary nebula has an irregular shape, looking sort of like the outside of an ear or a curled-up fetus. Two bright patches within a broader nebula section can be seen through amateur telescopes; a 10” or larger instrument is ideal.
One of the most enigmatic structures in Cygnus constellation is not technically a planetary nebula but a proto-planetary nebula known as the Egg Nebula (CRL 2688). Even an 8” telescope reveals the Egg as two dots of light, the beginnings of a planetary nebula’s hourglass shape viewed from a spectacular side angle.
Proto-planetary nebulae represent a short-lived phase between the asymptotic giant branch (AGB) star phase and the planetary nebula phase of some massive stars. Unlike a planetary nebula, which emits light from ionized gas particles heated from the death of the star, in a proto-planetary nebula, the main source of light is from the star, scattering off the gas and dust particles. This means proto-planetary nebulae are devoid of significant color and do not respond to filters, since they are essentially a type of reflection nebula.
The Egg Nebula is particularly famous for its complex structure and is enveloped in a dense cocoon of dust. The twin beams of light emanating from its center, likely due to its hidden central star, pierce through the surrounding dusty layers in polarized arcs. You can see this if you pop in a polarizing filter and rotate it, or if you wear sunglasses as you look through the eyepiece. The nebula brightens and dims depending on the angle of polarization!
The Footprint Nebula or Minkowski’s Footprint (M1-92) is another proto-planetary nebula in Cygnus, and its appearance fits the name. Like the Egg Nebula, this one can be tricky to spot since you can’t use nebula filters to narrow down your search. 200x or more and a 10” or larger telescope are needed to discern this faint fuzzy, as it is under 10 arc seconds in diameter – less than the maximum apparent size of Mercury. A 14” or bigger telescope gives the best views of the nebula.
Other Nebulae in Cygnus Constellation
Cygnus constellation is home to innumerable dark nebulae, countless faint and wispy molecular clouds, supernova remnants, and, of course, the more eye-popping sights listed here. Do note, however, that for these large, low-contrast objects, a dark sky and a good nebula filter are what will make or break the views.
One of the standout nebulae within Cygnus is the North America Nebula (NGC 7000). Aptly named for its uncanny resemblance to the North American continent, especially the Gulf of Mexico region, this emission nebula is vast, covering an area nearly four times the size of the full moon. Illuminated by a hot, young star, this nebula showcases regions of active star formation amidst its glowing gas. Adjacent to the North America Nebula is the Pelican Nebula (IC 5070 and IC 5067). Its designation comes from the bird-like shape observers can discern, especially the profile of a pelican’s head and beak. Both the North America and Pelican Nebulae are part of the same interstellar cloud of ionized hydrogen, with dark dust lanes creating their iconic shapes.
The North America Nebula and Pelican are visible to the naked eye under dark skies as glowing patches near Deneb. However, without sufficiently dark skies to see the Milky Way (and thus the nebulae) with your unaided eye, they are all but invisible in a telescope. Dark skies and a UHC filter are ideal for viewing these objects, as is as wide a field of view as possible. A hydrogen-beta filter also works but may muffle some of the North America Nebula region’s oxygen emissions. An OIII filter is not recommended. Additionally, telescopes providing a field of under a degree or so will not reveal the wider context of these nebulae, and it is easy to miss them entirely even if the conditions are good.
The enormous Cygnus Loop is the remnant of a supernova that occurred around 10–12,000 years ago, right around the end of the most recent Ice Age on Earth. It was almost certainly noticed by anyone looking up at the time, and would’ve been visible in broad daylight, like later recorded supernovae. The visible portion of the Loop is known as the Veil Nebula.
The Veil is split into three parts: the Witch’s Broom (NGC 6960), the Eastern Veil (NGC 6992/95), and the portion known as Fleming’s Triangle (formerly Pickering’s Triangle, the nebula was discovered by Williamina Fleming). The easiest to find and brightest portion is the Witch’s Broom, which is centered on the 4th-magnitude star 52 Cygni. Just find 52 Cygni and point at it, and you’ve got the Broom.
However, if you don’t see even the Witch’s Broom, don’t be surprised. The Veil requires at least a Bortle 5 (SQM ~20.0 or better) sky to be seen with a good UHC or oxygen-III nebula filter, and is virtually invisible unfiltered under all but the darkest skies. Bortle 3 (SQM >21.5) or so skies are ideal for the best view. A wide-field telescope is also best; the total Veil complex spans about 3 degrees, or six full moons, in apparent diameter, while the three main sections are each about 1.5–2 degrees wide. The good news is that aperture is almost completely irrelevant; if your skies and filter are good enough for the veil, even a 4” instrument gathers enough light to reveal the Eastern and Western Veil portions.
Through a small telescope, you can usually take in each of the Veil components in one view. The Broom shows a division into multiple wisps at one end, while the Eastern Veil is less dense but definitely thicker. Fleming’s Triangle is best on larger instruments. The better you get at observing, the better your skies are, and the better your equipment is, the more you’ll notice interesting fine details in the nebula and the more you’ll be able to tell that the entire complex never really ends or breaks up; bright portions merely fade into dimmer ones, making a nearly unbroken cloud like what is seen in long-exposure astrophotos.
The Cocoon Nebula (IC 5146), located near M39, is an emission and reflection nebula accompanied by an embedded open star cluster around 4,000 light-years away. Through a telescope, the Cocoon Nebula presents a soft, glowing patch of light with a distinct elongated shape. A UHC filter brings out detail in the emission component. Barnard 168, a dark nebula, cuts through the middle of the Cocoon and is also fairly distinct at the eyepiece.
Surrounding the bright star Sadr (Gamma Cygni) is the expansive and intricate Sadr Nebula (IC 1318). IC 1318 is an emission nebula that, when viewed through a wide-field telescope and UHC filter, offers a complex tapestry of glowing gas and dark dust lanes. A night vision device works spectacularly well on this object as well.
Located about 6,000 light-years away, the Tulip Nebula near Eta Cygni is characterized in astrophotos by its vibrant red hue, the result of its predominantly hydrogen constitution. Its resemblance to a blooming tulip gives it its popular name. The Tulip is hard to see through most backyard telescopes, but under dark skies, it is modestly apparent in instruments as small as 6”; a H-Beta or UHC filter works well. Observers with keen eyes and larger telescopes might also note the shockwave from Cygnus X-1 intersecting the nebula, adding a layer of dynamism to the already captivating view.
Then there’s the Crescent Nebula (NGC 6888). Born from the powerful winds of a dying Wolf-Rayet star, this emission nebula exhibits a crescent or Euro sign shape. The intense stellar winds collide with the material ejected by the star in the past, compressing the gas and causing it to glow brilliantly. A UHC or O-III filter is practically required to bring out the Crescent; it largely submerges into the background unfiltered, though with a filter even an 8” reveals the nebula’s wispy tendrils.
Located near the star Deneb, Sharpless 112 is a faint emission nebula that provides a challenge and reward for seasoned observers. Through larger amateur telescopes and under dark skies, this nebula unveils a delicate, wisp-like structure. Its faint glow contrasts with the surrounding dark regions, making it a treat for those seeking subtler celestial wonders.
Galaxies in Cygnus Constellation
Spanning the border of constellations Cygnus and Cepheus (literally), lies Cygnus’ sole noteworthy galaxy, NGC 6946. NGC 6946 is a spiral galaxy that we view face-on. It is commonly known as the Fireworks Galaxy, as more supernovae have been seen in NGC 6946 than have been seen in any other individual galaxy. Since 1917, 10 have occurred, with the most recent being in 2017. All of these were also Type II supernovae from the explosions of massive stars, which points to NGC 6946’s rapid star-forming nature since Type I supernovae (from white dwarfs exploding) are far more common and are still relatively rare in most galaxies. This leads to the galaxy’s classification as a starburst galaxy like M82.
The easiest way to find NGC 6946 is to use the open star cluster NGC 6939 in neighboring Cepheus as a guide; the cluster is visible even in binoculars and is quite spectacular in medium-sized telescopes, but falls outside the purview of this article owing to its placement.
NGC 6946 is rather dim, partly due to its location in the sky; dust from our own Milky Way blocks the majority of incoming light. If it were placed somewhere else in the sky, NGC 6946 would be brighter than Andromeda and easily visible to the unaided eye as a dense, fuzzy patch. However, as it stands, NGC 6946 is a rather low-contrast object owing to its obscuration by dust and the inherently dim nature of face-on spiral galaxies.
Binoculars and small telescopes reveal NGC 6946’s core as a faint patch of light; a 6” reveals a fainter outlying region, while an 8-10” instrument under dark skies begins to reveal the spiral nature of the galaxy. A 16” or larger aperture under a dark sky provides a spectacular view of the galaxy’s spiral arms and nebular H-II regions. However, like all galaxies, under a light-polluted sky, NGC 6946 will appear washed out no matter how capable your telescope is.