Cygnus Constellation: All you need to know about the 'Celestial Swan'

It is one of the most fascinating, and beautiful, collections of stellar objects we can see from Earth.
Christopher McFadden
Cygnus Constellation.
Cygnus Constellation.

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  • The Cygnus Constellation was first recorded by Claudius Ptolemy thousands of years ago.
  • It is one of the most prominent and simplest constellations to find in the night sky.
  • Modern science has discovered that the constellation is home to many very interesting celestial bodies.

The "Celestial Swan," otherwise known as the Cygnus Constellation, is one of the most widely studied and, frankly, most beautiful regions of the night sky. Known for many thousands of years, it still fascinates human beings to this very day.

Let's find out why.

What is the Cygnus constellation?

Cygnus is one of the most prominent constellations in the northern sky. Its name is Latin for "the swan," and so it is also commonly referred to as the "Swan Constellation."

Cygnus is one of the most well-known constellations in the northern summer and fall and has a prominent asterism (a collection of stars smaller than a constellation) called the Northern Cross (in contrast to the Southern Cross). This feature is so prominent that the entire constellation is also known as the "Northern Cross."

Cygnus is one of the 88 "official" constellations that are visible today. It was one of the 48 constellations that the 2nd-century astronomer Ptolemy recorded.

Forming one corner of the Summer Triangle and one of the brightest stars in the night sky, the star Deneb is found in Cygnus. It is also one of the most distant first-magnitude stars.

A few noteworthy X-ray sources, including the massive star association Cygnus OB2, are also found in Cygnus.

Cygnus Constellation: All you need to know about the 'Celestial Swan'
Artistic representation of the constellation.

The constellation is also home to one of the biggest stars currently known, NML Cygni. Cygnus X-1, a far-off X-ray source with an undetected huge supergiant companion and which was the first object that is widely believed to be a black hole, is likewise located in the constellation.

Largely as a result of the Kepler Mission's observation of one region near Cygnus, many star systems in Cygnus have been found to also contain exoplanets.

How do you find Cygnus?

Cygnus is one of the most beautiful constellations and one of the easiest to find in the night sky. This is especially the case if you are far from light pollution. The best way to locate it is by finding the Northern Cross — five stars in a cross shape that make up its bulk, which runs through the Milky Way.

According to some sources, the Northern Cross can be seen in the sky all year long, but its position varies with the seasons.

Cygnus Constellation: All you need to know about the 'Celestial Swan'
The Cygnus Constellation with the Milky Way.

To look for it, search for the bright star Deneb, which is located at the swan's "tail" and whose name, conveniently, is derived from the Arabic word for "tail," to confirm that you are viewing Cygnus. The word 'Deneb' is also used in the Arabic expression "Al Dhanab al Dajjah," which means "the hen's tail."

Along with Altair and Vega, Deneb is a member of the so-called "Summer Triangle," a group of three neighboring brilliant stars. The star is a blue supergiant that lies between 2,100 and 7,400 lightyears away from Earth and is 60,000 times more luminous and 20 times more massive than our Sun.

The swan's tail is a type of variable star, which means that as its surface dramatically expands and contracts over time, it changes in brightness. Interestingly, this star is also believed by some to be on the verge of a supernova explosion, which is anticipated to occur within the next few million years.

Over thousands of years, the Earth's axis wobbles and points at different stars that serve as the North Star. Polaris is currently the North Star, but Deneb will likely replace Polaris as the North Star somewhere around the year 9800.

Gamma Cygni, often known as Sadr, is the star at the center of the Northern Cross. According to Universe Today, its name derives from the Arabic term for "the chest." It's about 1,800 lightyears away from Earth and is also a blue-white supergiant.

Albireo is the star that appears as the swan's head or the top of the cross. This star is not extremely brilliant but is a favorite among astronomers because, when viewed through a tiny telescope, it reveals itself to be two stars close to one another.

The Veil Nebula, a stunning nebula, is located inside Cygnus' wing, just beyond the left side of the cross. The North American Nebula is another magnificent celestial object that may be seen behind Deneb. Both can only be seen under dark skies with the aid of binoculars or a telescope.

What exactly is a constellation?

Constellations are groups of stars in the sky that form a specific recognizable pattern. This pattern they make is often the subject of a little artistic licensing, but the stars that form constellations can generally be viewed from Earth without the use of a telescope when the sky is clear.

There are 88 constellations with names, and they can describe mythical beings, animals, humans, or objects. Typically, a constellation's name is determined by the form created by its brightest stars. These shapes come in a variety of forms, some more visible than others. An asterism is a smaller shape or pattern which can be identified inside a constellation and sometimes given a name of its own.

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For many thousands of years, people have observed the stars, and 48 of the 88 constellations that are recognized today had their names originally given to them in ancient Greece. The Latin word "constellatio," from which we get the English "constellation," means "set with stars."

Cygnus Constellation: All you need to know about the 'Celestial Swan'
Star constellations of the Northern Hemisphere.

Prior to the development of modern navigation, humans mostly used the stars for navigation when sailing across the ocean. They located Polaris, often known as the North Star, by using a constellation called Ursa Minor. They were able to determine their latitude and direction of travel thanks to this.

Even though the general arrangement of the stars doesn't change throughout the year, people have utilized the precise location of particular constellations to denote seasonal changes. Obviously, it's not the stars gliding through the sky. It is the Earth shifting our perspective as it travels through space.

A star chart known as a planisphere can be used for this. It has movable wheels all the way around it. The wheels can be modified to show an exact depiction of the sky and the constellations that should be visible to you at the time of year and location on Earth.

What are some fun facts about Cygnus?

We've already covered quite a few facts about this stunning and ancient constellation, but if you are hungry for more information, then here are some select titbits about it.

1. Cygnus is associated with several ancient Greek myths

Cygnus Constellation: All you need to know about the 'Celestial Swan'
In Greek mythology, Cycnus is turned into a swan to help his friend.

The constellation Cygnus is linked to a number of legends. Perhaps the most noteworthy of these is the myth surrounding Cycnus and Phaeton (mortal son of Helios, the Sun God) and their friendship.

According to mythology, the two friends were competing in an aerial race. They flew too close to the Sun as the race heated up, which sadly caused their chariots to catch fire. Subsequently, they both fell back to Earth in an almighty crash.

When Cycnus came to, he looked for his beloved companion Phaeton and discovered his lifeless body at the bottom of the Eridanus River.

He made a deal with Zeus, the God of Gods, because he was unable to retrieve his friend's body with his mortal human body. But, should Zeus agree to help, he would be transformed into a swan and only live as long as a swan naturally would.

The deal was made, and Cycnus was able to visit his friend's corpse and give him a suitable burial, allowing Phaeton's soul to pass to the afterlife.

Cycnus' deed moved Zeus, who later placed him in the sky in his swan form as a symbol of friendship and sacrifice.

But, the Cygnus constellation also has myths in other cultures too, notably the Chinese.

According to the "magpie bridge" tradition, Niu Lang and Zhi Nu were profoundly in love, but the Goddess of Heaven forbade them from being together because Zhi Nu was a fairy and Niu Lang was simply an ordinary mortal.

But even the gods could not stop love, and the couple got married secretly. The Goddess did not approve of the secret marriage, so she created a celestial river in the sky to separate the lovers. This river represents the Milky Way, our very own galaxy.

According to folklore, all the magpies get together each year to create a massive bridge over the river in order to reunite the lovers. This bridge is the Cygnus constellation.

2. Cygnus is home to several "Deep-Sky" objects

Cygnus Constellation: All you need to know about the 'Celestial Swan'
Messier 29.

Cygnus contains a variety of deep-sky objects (DSO), including supernova remnants and emission nebulae. In case you are unaware, DSOs are any astronomical object that is not an individual star or Solar System object (such as Sun, Moon, planet, comet, etc.).

For example, nebulous regions abound in the Cygnus constellation, notably the Sadr region that contains the Butterfly Nebula.

There are a lot of New General Catalogue of Nebulae and Clusters of Stars (NGC), Index Catalog (IC), and Sharpless Catalog objects in Cygnus despite the fact that there are only two Messier objects (Messier 29 and Messier 39).

In the Northern Cross's crossing is the star Sadr (Gamma Cygni). Alongside Deneb, this is the brightest star in Cygnus, which is also inside the areas of the Northern Cross. The equally brilliant and magnificent North America Nebula is also located there.

3. Cygnus is also home to the binary star system "Bessel's Star" (aka 61 Cygni)

One of the most exciting things about Cygnus is the presence of the binary star system known as 61 Cygni. It is made up of two K-type (K5V and K7V) dwarf stars in the main sequence that orbit one another about every 658 years. Their relative apparent magnitudes are around 5.21 and 6.03.

What's more, it is pretty close to us as only 11.41 lightyears separate our solar system from 61 Cygni. It is the 28th-nearest known star system to us.

The brightest member of the system, Cygni A, is the fourth closest star to Earth that can be seen with the unaided eye, behind Procyon A in Canis Minor, Sirius in Canis Major, and Epsilon Eridani in Eridanus. It is believed that by the year 20,000, it will approach the solar system within nine light years.

The angular shift in location over time, as seen from the solar system's center of mass, is known as the proper motion, and 61 Cygni is famous for having a large proper motion.

Cygnus Constellation: All you need to know about the 'Celestial Swan'
A size comparison between the Sun (left), 61 Cygni A (bottom) and 61 Cygni B (upper right).

Giuseppe Piazzi, an Italian astronomer and mathematician, was the first to prove the star's proper motion in 1804. He gave 61 Cygni the nickname of Flying Star.

This star is also the first star other than the Sun, whose distance to Earth was reliably determined. This was done using the parallax method by measuring the displacement of the star's apparent position as seen from two separate lines of sight and the angle of inclination between the two. In 1838, German astronomer Friedrich Wilhelm Bessel used the parallax method to determine the distance to 61 Cygni as 10.4 lightyears, which is close to the actual distance we know today, 11.4 lightyears. The star was an excellent choice for this because of its strong proper motion.

4. 34 Cygni (P Cygni) is a very rare kind of star

A hypergiant bright blue variable (LBV), P Cygni is a variable star. Variables with luminous blue light are uncommon and only occur in areas with active star formation. They typically don't last long.

Due to their huge mass and energy, they swiftly run out of nuclear fuel and explode into supernovae within a few million years. For comparison, our Sun has existed for many billion years.

P Cygni is about 5,500 light years away from Earth and is in the spectral class B1Ia+. It is one of the Milky Way's most brilliant stars ever found.

In August 1600, Dutch astronomer Willem Janszoon Blaeu made the first recorded observation of P Cygni. Because it barely brightened to the third magnitude in the last few years of the 16th century, it had not been found earlier. It faded once again in 1626, then brightened once more in 1655 before fading once more in 1662.

Around 1715, the star's brightness variations became less pronounced. Since then, it has remained a fifth-magnitude star. With oscillations of up to 0.5 magnitudes, it has an apparent magnitude of 4.8 right now.

The star was given the designation P by Johann Bayer. P Cygni is occasionally referred to as a perpetual nova due to its abrupt brightness shifts, even though the star does not behave in the manner of a real nova.

5. The Cygnus constellation also encompasses the beautiful Veil Nebula

Cygnus Constellation: All you need to know about the 'Celestial Swan'
The Veil Nebula.

The Veil Nebula is the visual component of a part of the constellation called the Cygnus Loop. This is believed to be the remnants of a now long-since-over large supernova.

It has multiple parts, including the Western Veil (NGC 6960), the Eastern Veil (NGC 6992, NGC 6995, IC 1340), and Fleming's/Pickering's Triangle Wisp. It is also known as the Cirrus Nebula or the Filamentary Nebula.

The Witch's Broom is another name for NGC 6960, commonly known as the Western Veil. It makes up the nebula's westernmost portion. Three bright regions make up the Eastern Veil: NGC 6996, NGC 6995, and IC 1340.

The American astronomer Williamina Fleming discovered Pickering's Triangle, also known as Pickering's Wedge or Pickering's Triangular Wisp, in 1904. Fleming named the object Pickering's Triangle after the director of the Harvard Observatory, where Fleming made the discovery, Edward Charles Pickering.

Another pair of nebulosity areas, NGC 6974 and NGC 6979, can be found in a cloud towards the nebula's northern edge. NGC 6974 was found by British astronomer Lord Rosse and NGC 6974 was found by William Herschel.

The Cygnus Loop has a diameter of about 120 lightyears and is located about 1,500 lightyears away from Earth. The supernova remnant is thought to be between 5,000 and 8,000 years old.

6. There is also a nebula within the constellation that looks a lot like North America

Cygnus Constellation: All you need to know about the 'Celestial Swan'
North America Nebula (top) and Pelican Nebula (bottom).

Because of how closely NGC 7000 in Cygnus matches the shape of the North American continent, it was given the moniker the North America Nebula. The nebula's appearance is affected by a belt of dust that blocks out most of it.

However, this is only really relevant depending on the way you actually view the nebula. It looks completely different if viewed, for example, using visible light or, alternatively, observing the nebula using infrared only.

When viewed under visible light, the shape of the nebula really appears to be a doppelganger for North America.

The distance between it and Earth is roughly 1,600 light years, and its apparent magnitude is 4.

The North America Nebula is incredibly huge, measuring around 120 by 100 arc minutes, yet due to its dim surface brightness, it is typically impossible to observe without binoculars. On October 24, 1786, William Herschel made the discovery.

Cygnus Constellation: All you need to know about the 'Celestial Swan'
The North America Nebula (NGC 7000) is one of the most well-known nebulae in Cygnus.

The section of the nebula known as the Cygnus Wall, which is the portion that corresponds to the Mexico and Central America region, has the highest concentration of star formation activity (so to speak).

The nearby Pelican Nebula (IC 5070) and NGC 7000 are both a component of the same H II region, an interstellar cloud where stars are produced.

7. Theta Cygni might just have an exoplanet the size of Jupiter

About 59.8 light years from our solar system, Theta Cygni is a main sequence star in the spectral class F3 V. It has a 4.490 apparent magnitude. It has around 38% greater mass and is four times as bright as our Sun, and it is believed to be between 0.6 to 1.9 billion years old.

The star has a faint companion, with a magnitude of 13.03, located about three arc seconds away. The companion is a red dwarf belonging to the spectral class M3 V.

Another interesting feature of Theta Cygni is that its system may have an extrasolar planet. The ELODIE team found radial velocity differences that point to the presence of a planet with an orbital period of fewer than six months around the star. The planet, which is thought to be twice the size of Jupiter, has not yet been identified.

8. Delta Cygni may replace the North Star in a few thousand years

Another interesting component of the Cygnus constellation is the triple star system called Delta Cygni. Around the year 11,250, it will take over as the North Star for at least 400 years. The star system is around 165 light years away and has a combined apparent magnitude of 2.87.

The Delta Cygni system consists of two stars that are near to one another and a third star that is a little farther away. Its brightest star, a blue-white behemoth in the spectral class B9 III is nearing the end of its life cycle on the main sequence. With an equatorial speed of at least 135 kilometers per second, it is a rapidly revolving star.

The star's nearest companion is a yellow-white star with an apparent magnitude of 6.33 that belongs to the spectral class F1 V. A 12th magnitude orange giant makes up the Delta Cygni system's third element.

9. The Fireworks Galaxy is aptly named

Cygnus Constellation: All you need to know about the 'Celestial Swan'
The Fireworks Galaxy.

Another fascinating feature of the Cygnus constellation is the intermediate spiral galaxy Fireworks Galaxy (NGC 6946). It is roughly 22.5 million lightyears away, has an apparent magnitude of 9.6, and has a diameter of between around 40,000 lightyears and 73,000 lightyears.

The galaxy is situated close to Cepheus' constellation boundary. It is heavily veiled by Milky Way interstellar matter and is located not far from the galactic plane.

The galaxy was first discovered on September 9, 1798, by British astronomer Sir Frederick William Herschel, who assumed it was a gaseous nebula. According to NASA, the galaxy has witnessed ten observed supernovae in the last century, earning it the nickname Fireworks Galaxy. In comparison, the Milky Way averages around one or two supernova events per century.

10. One Cygnus X is the strongest alien X-ray source to Earth and could be a black hole

Cygnus Constellation: All you need to know about the 'Celestial Swan'
X-ray image of Cygnus X-1 taken by a balloon-borne telescope, the High-Energy Replicated Optics (HERO) project.

One of the strongest X-ray sources that can be viewed from Earth is Cygnus X-1. It was initially discovered during a rocket mission in 1964 by a pair of Geiger counters placed aboard a sub-orbital rocket. The Geiger counters picked up a signal that was traced back to Cygnus X-1.

Despite having a mass around 21 times that of the Sun, Cygnus X-1 is famous for being the first X-ray source that was universally accepted to be a black hole candidate. It has also been found to be spinning incredibly quickly — very close to the speed of light and faster than any other black hole found to date.

In fact, in 1975, physicists Stephen Hawking and Kip Thorne engaged in a friendly scientific wager regarding Cygnus X-1, with Hawking betting that it was not a black hole. In 1990, once observational data had made it clearer that the system did indeed appear to include a black hole, he finally gave in. Although there isn't any direct empirical support for this claim, there is indirect support for it.

The object is about 6,190 light years from us here on Earth.

Cygnus Constellation: All you need to know about the 'Celestial Swan'
Chandra X-ray Observatory image of Cygnus X-1.

Cygnus X-1 is part of a binary system with HDE 226868, a blue supergiant variable star, around which it orbits. Cygnus X-1 is surrounded by an accretion disc that has developed over time from material transported from the star by a stellar wind.

And that is your lot for today, constellation connoisseurs.

The Cygnus Constellation is one of the oldest and most easily recognizable collections of stars in the night sky. First recorded by Ptelomy thousands of years ago, you can bet your bottom dollar it has been known about for much, much longer than that.

Like most star constellations, it is constantly changing, and in a few thousand years' time or more, it will morph and change as the universe around us evolves with time. It may change so dramatically that future generations may wonder why we call it the "Swan" constellation.

Assuming they know what a swan is, of course.

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