Solar System

(The Swan)

Stretching its way across the summer sky in the northern hemisphere, Cygnus is a large and easy to find constellation that is host to dozens of amazing nebulae and clusters. The constellation is sometimes referred to as the Northern Cross as it resembles a cross.

The brightest star Deneb is 33% of the asterism, the Summer Triangle. Other interesting stars include Sadr, which is a bright blue giant and Albireo, an iridescent pair of stars that are blue and gold.

Most of the constellation is covered by the silvery blanket of the Milky Way. The Milky Way near the centre of the constellation is obscured by a giant elongated dark cloud called the Great Rift, which is also alternatively referred to as the Northern Coalsack. It starts south of Deneb and winds its way downwards like a dark spectre in front of the Milky Way.

  One of the many treasures waiting to be found in Cygnus is Albireo, a charming pair of gold and blue stars.  
  Image copyright S. Heutz (Astro-cooperation)  

Cygnus is home to one of the most interesting stars, 61 Cygni. It is sometimes called Piazzi's Flying Star as it was discovered by Giuseppe Piazzi in 1804. He was a famous astronomer who discovered the very first asteroid, Ceres in 1801.

One of the interesting factors about 61 Cygni is that it is a double star but both members are also variable! The other fact that is slightly more amazing is that it has a huge proper motion. Proper motion is the movement of a star relative to more distant stars. Piazzi's Flying Star moves across the sky so rapidly that it covers a distance equivalent to the apparent diameter of the full Moon in a swift 340 years!

More amazing attributes of this star include the fact that it is 10 billion years old, making it twice as old as the Solar System! It can also be seen with the naked eye but either binoculars or a small telescope will be necessary to see both components.

Standing in the freezing cold of a midsummer night, gazing upwards at the night sky, when you look at this star, you might contemplate the brevity of mankind and how the duration of mankind's existence is nothing but a tiny dot in comparison to the ancient blazing furnace of light that has looked down upon our planet and watched civilisations rise and fall and will continue to observe the dwindling timeline of humanity until it culminates in the death of the Sun and the obliteration of our planet. Despite all this, 61 Cygni will probably continue to cast its light across the vastness of the cosmos until its inevitable end.

    Cocoon Nebula    
    The Cocoon Nebula is one of the many stunning nebulae in Cygnus. Popular with imagers, it seems to be given less attention by visual observers because of its faintness and the presence of bright stars in front of the nebula makes it challenging to see. The blue nebula is catalogued as vdB147.    
Image copyright R. Jay GaBany
An ancient star cluster, M39 contains about 30 stars with the Milky Way as an elegant backdrop. It is very loosely spread so a pair of binoculars is the best instrument to view it in. A claim to fame, albeit a historical one is that Aristotle the Greek philosopher saw it as a misty patch with his eyes. It might be possible to see this cluster with the unaided eye under a dark sky away from light pollution.
Less impressive than M39, this clutch of 20 stars is an attractive sight through binoculars but less impressive through larger telescopes probably because they have a closer view and a wider view is needed to fully appreciate the cluster. The cluster is backdropped by a curtain of nebulosity catalogued as DWB 33.
North America Nebula (NGC 7000):

Serendipity is the cause for the shape of this nebula as its appearance is eponymous with the Earthly continent. The illusion of a North America shaped cloud in space is due to a dark nebula situated in front of a large emission nebula that also incorporates the adjacent Pelican Nebula.

The nebula is located between the stars Xi Cygni to the left and Deneb (Alpha Cygni) to the right, which can be seen in the impressive image at the bottom of this page. Some observers have claimed it to be visible with the naked eye and perhaps it is with a nebula filter.

Pelican Nebula (IC 5070) and Mountains in the Mist (IC 5067):

The large beak of this bird shaped nebula is a slightly comical sight in the night sky. It is to the right of the significantly brighter North America Nebula and below it lies an amorphous elongated cloud called IC 5068.

Near the beak lies the Mountains in the Mist, which are a series of mountain shaped pillars that are part of something known as an ionization front. This rare feature is formed when the intense ultraviolet radiation from hot stars washes over much denser gas and dust. The denser area of gas and dust is eroded away and the ionization front is more easily visible in false colour images as opposed to true colour.

Butterfly Nebula (IC 1318):

A bi-lobed emission nebula, this nebula is like a celestial butterfly floating amongst the widespread cocoon of surrounding HII nebulosity. Like the North America Nebula, its fabulous shape is created by a dark nebula obscuring the centre of the nebula. The nebula is called LDN 889 and it spills like a dark poisonous snake towards south of the star Sadr (Gamma Cygni). Sadr is Arabic for 'chest' and this star represents the chest of the swan. Deneb represents the tail of the swan.

Because it appears to enshroud Gamma Cygni, the nebula is also alternatively named as the Gamma Cygni Nebula. The nebula is completely unrelated to the star and they are both at different distances. Sadr is 750 light years away and
IC 1318 is 5000 light years away.

Crescent Nebula (NGC 6888):

A curious shaped nebula that is considerably south of Sadr, it is one of the few Wolf Rayet nebulae in the Milky Way. Its central Wolf Rayet star casts its light and energy to illuminate the tangle of filaments and arcs that overlap with many being adjacent to each other. Long exposure images have also shown the crescent shape to actually resemble the number three. This shape is caused by filaments that seemingly extend from the Wolf Rayet star.

The main structure was created when winds from the central star crashed into the surrounding interstellar medium about 250 000 years ago. Shock waves created shells that were ionized by the ultraviolet radiation from the Wolf Rayet star. This ionization process is what caused it to be visible in the optical wavelength. The lifetime of the nebula is limited, it will disappear in 10 000 years time.

Veil Nebula (NGC 6960, NGC 6992, NGC 6995 and NGC 6979):

It seems inconceivable that a process that is designed to destroy can create something of such delicate beauty. The object that was destroyed was a star in a titanic supernova explosion and what was created were tendrils of gas that are the supernova remnant. This remnant is not actually the gas from the dead star but is produced by the shock front released by the supernova propelling into the adjacent interstellar medium. The interstellar medium that has contact with the shock front gains new energy that causes the gas to glow in different wavelengths including optical and x-rays.

The Veil Nebula is divided into three parts. The brightest is known as the Network Nebula and is NGC 6992-5. This is on the left side and is an arc of pinkish gas. Directly opposite is the aptly named Witch's Broom Nebula alternatively known as NGC 6960. Near the centre glows a bright yellow star called 52 Cygni. Not directly in between but to the left of NGC 6960 is a triangular part called Pickering's Triangle, named after William Pickering by his assistant, Williamina Fleming who discovered it. It is also known as Fleming's Triangular Wisp and the NGC designation is NGC 6979.

Veil Nebula
The wispy web of nebulosity belonging to the Veil Nebula covers a large area towards the left side of Cygnus. The arc on the left is the Network Nebula, the triangle in the middle is Pickering's Triangle and the Witch's Broom Nebula is on
the right. The bright yellow star near the middle of the Witch's Broom is 52 Cygni.
Image copyright S. Cannistra
Cocoon Nebula (IC 5146):

Like a giant fluffy pink and purple marshmallow, the Cocoon Nebula is a tasty looking mixed emission and reflection cloud at the end of a strip of dark nebulosity catalogued as B168. Finding the nebula is easy, once you have found a starless void, follow it until you notice the soft gossamer glow of the 7th magnitude nebula. This approach is comparable to following a trail of breadcrumbs although the trail that leads to the Cocoon Nebula is an empty void of black darkness. Completely surrounding both nebulae is the milky glow of thousands of stars, a truly enchanting and magical spectacle that can be witnessed in all its splendour by anyone at a dark sky site.

The Cocoon Nebula has spawned an open cluster and branches of stars can be found at the centre and some of these are T Tauri type stars, also there are some Herbig Haro objects present. The emission part is obscured by many dark chocolatey lanes that give the nebula a slight sense of depth and texture. The reflection part surrounds a Herbig Haro star. The Cocoon Nebula was discovered in 1899 by the British astronomer Thomas Henry Espin and was photographed a year later by Max Wolf. It was also included in the Sharpless Catalogue of HII Regions as Sh2-125.

NGC 6914:
Lighting up the seemingly neverending arcs of nebulosity that pervade the northern half of Cygnus, NGC 6914 is a pair of electric blue reflection nebulae. Surrounding the pair is an enmeshment of ruby red emission nebulosity which gives the area the appearance of two sapphires encrusted with ruby jewels.
Blinking Nebula (NGC 6826):
Like a cosmic mirage, something unexpected will occur when you gaze at the central star of this vivid blue green planetary nebula. The shell will disappear and when you glance away from the star, it reappears like magic! This is definitely not your average planetary nebula. The blinking effect only works with small telescopes.
NGC 7008:
Encrusted within a starry field, this jewel of a planetary nebula is an overlooked treasure. The size of the glowing magenta shell is ample enough to be seen in small telescopes, the other factor that contributes to its ease of visibility is the respectable magnitude of 10.7 as well as the small size resulting in a high surface brightness. It would appear larger if it was closer than its distance of 2800 light years although larger telescopes can unveil the delicate gossamer of its beauty in all its entirety and large apertures also reveal the structure to incongruously resemble an embryo, therefore NGC 7008 is commonly referred to as the Fetus Nebula. This enchanting nebula was discovered by William Herschel in 1787.
NGC 7008   Fish on the Platter (B144):
  Like a gaping mouth engorging on the infinite banquet of the Milky Way, the curiously named Fish on the Platter is a dark nebula that surprisingly resembles a fish placed on top of a platter. It is near the active x-ray source Cygnus X-1.

One of the lesser known planetary nebulae in Cygnus, NGC 7008 is an enchanting bauble attached to the surging river that is the Milky Way. The deformed sphere and the presence of violet and aquamarine hues suggest a similarity with NGC 246 in Cetus.

It is a possibility that we see NGC 7008 from the side rather than face-on. It is also highly likely that the structure doesn't consist of one round sphere but rather a series of interlapping shells.

Quite curious is the reddish knotty jet towards the north, it is possible that it was ejected by the central star prior to the formation of the shell. Also intriguing is the absence of gas around the magnitude 13 central star, incredulously this is a part of the nebula that was destroyed by a nova!

Faint but pretty, this oval shaped emission nebula is next to the binary Cygnus X-1 System. This is a pair consisting of a blue giant orbiting a black hole.

Sh2-101 is strong in hydrogen alpha and sulphur emissions and it has an unexpected but profound relation to our Solar System, they both lie in the same spiral arm of the Milky Way.

Image copyright D. Hager/D. Goldman/P. Mortfield
To the right of Deneb, Sh2-112 is a bit like an upside down version of the Pacman Nebula in Cassiopeia. The similarity is due to a dark lane at the top that also has multiple tiny lanes emanating from the main lane. The nebulosity above the lane is small and more red and the nebulosity below is oval shaped with a pinkish tinge.
NGC 6894:
One of a few planetary nebulae in Cygnus, NGC 6894 is an electric web of gas in a pink inner shell. It is also comprised of a fainter outer shell that surrounds the brighter inner shell.
A bit of galactic subterfuge is involved with this fascinating nebula. On the outside, it gives the appearance of a bi-lobed planetary nebula but is in fact an emission nebula. The shape is uncommon for emission nebulae and is caused by the stars inside releasing strong winds that force gas into the bipolar shape.
Like a mini version of NGC 6914, this is a reflection nebula surrounded by red emission. The reflection part is associated with the star 44 Cygni.
Located left of the North America Nebula, Sh2-119 is a very large and faint cloud of HII emission that surrounds the star 68 Cygni. It lies in a overpowering field of Milky Way stars, the ideal method of observation is using a filter that increases contrast between the nebula and the background.
Abell 78:
An incredibly and wonderfully bizarre planetary nebula, Abell 78 is a perfect embodiment of stellar recycling. The main knotty structure is a cloud of helium encased in a outer shell of hydrogen; elements required for nuclear fusion. This hydrogen will be absorbed by the interstellar medium and reused as fuel for the formation of a new generation of stars. Abell 78 lies in an area that is fairly devoid of the Milky Way, therefore many background galaxies litter the surrounding area.
Campbell's Hydrogen Star:
When observing this object through a small telescope, the impression is that one is looking at a highly reddened star. Despite the misleading name, it is actually a planetary nebula! It was discovered in 1893 by William Campbell and it can be found near the bright pair of stars that is Albireo.