Constellations

Cygnus the Swan flies along the Milky Way

Sky chart showing Cygnus looking like a sideways cross with 2 stars labeled.
Cygnus the Swan’s brightest star, Deneb, marks one of the corners of the Summer Triangle. And its bright double star, Albireo, is one of the finest in the heavens.

If you have a dark sky, it’s easy to see the edgewise view into our own galaxy – our Milky Way – spun across the heavens. As you look toward it, you’ll be gazing toward the constellation Cygnus the Swan, too. Its brightest star is called Deneb, the Swan’s Tail. And the constellation Cygnus contains one of the most beloved double stars in the sky, blue and gold Albireo.

Plus, the star Deneb marks one of the corners of the famous Summer Triangle, an asterism composed of three bright stars in three different constellations.

So there’s a lot going on in this part of the sky! And no wonder, because the Swan lets you peer into the depths of the Milky Way.

How to find Cygnus the Swan

You can find Cygnus high above the eastern horizon after sunset in summer. As the sky grows dark, the first of its stars that you’ll see is Deneb, the brightest in the constellation at magnitude 1.25. Deneb is the tail feather of the Swan, or the top of the lowercase “t” shape. In addition, Cygnus also has the nickname of the Northern Cross.

Later, as the night wears on, you’ll be able to trace out the body of the Swan and its bent wings. Then, you can find the double star, Albireo, which marks its head.

If you can find the large Summer Triangle shape, Deneb in Cygnus is the star that lies toward the northeast.

Once you’ve found Cygnus, you just need to look along its length to find the hazy cloud behind it that is our galaxy, the Milky Way. The Milky Way, notably, runs along the same axis as the long line of the lowercase t or the body of the Swan.

Star chart with the Summer Triangle in purple, with Cygnus constellation in blue over the triangle.
The bright star Deneb is part of the famous Summer Triangle asterism. Its constellation, Cygnus the Swan, flies across the summer evening sky.

The Swan in skylore

The mythology of Cygnus tells the story of Zeus, who changed into the form of a swan to entice Queen Leda. From their union came the twins Castor and Pollux.

We see them today as the bright stars of the constellation Gemini the Twins.

Stars of the Swan

Deneb, or Alpha Cygni, is the 19th brightest star in the sky. At magnitude 1.25, it’s a blue-white supergiant star lying about 1,500 light-years away, which is a long distance for a star that shines so brightly in our skies.

Albireo, the head of the Swan, is largely regarded as the most beautiful double star in the heavens. Indeed, you can easily divide Albireo into a larger yellow star and smaller blue star in a small telescope. The brighter star of Albireo (or Beta Cygni) is magnitude 3.1, and the dimmer is magnitude 5.8. The stars are approximately 380 light-years distant.

Omicron Cygni, or 30 and 31 Cygni, is a double star with orange and blue components that you can see with binoculars. These stars lie between Deneb and Delta Cygni, which is the western wing of the Swan. At magnitudes 4.8 and 3.8, 30 and 31 Cygni lie 610 and 1.350 light-years away, respectively.

Gliese 777 is a yellow subgiant star shining at 5.71 magnitude and located about 51 light-years distant. Two extrasolar planets have been confirmed in its system.

Star chart with stars in black on white with constellation Cygnus the Swan, and nearby Lyra the Harp.
The constellation Cygnus with its stars, that form an asterism known as the Northern Cross. Image via IAU/ Sky & Telescope/ Wikimedia Commons.

Deep-sky objects in Cygnus

In addition, you can find an open cluster in Cygnus lying less than two degrees from Sadr, or Gamma Cygni, the third brightest star of the constellation, at magnitude 2.23, at the center of the cross or Swan. This open cluster is M29, at magnitude 7.1. With this in mind, try using binoculars to track it down.

Also, another Messier object in Cygnus is M39, an open cluster lying about nine degrees northeast of Deneb. M39 is magnitude 5.5. In this case, you can try to spot with just your eyes alone.

Now, head back to Sadr. A 7.4-magnitude open cluster, NGC 6910, lies just a 1/2 degree north of the star. Scanning along the western boundary of Cygnus with binoculars or a telescope reveals other clusters, including the magnitude 7.3 Foxhead Cluster (NGC 6819) and the 6.8-magnitude Hole-in-a-Cluster (NGC 6811).

Also, on the western side of the constellation, 5 1/2 degrees north of Sadr, or Gamma Cygni, is the 8.8 magnitude Blinking Planetary, NGC 6826. To be sure, as you move your eyes across it, does it appear to blink?

Large clouds of red-colored gas over a multitude of distant stars.
View at EarthSky Community Photos. | Andy Dungan near Cotopaxi, Colorado, captured this image of the Sadr Star Region in Cygnus on May 25, 2023. Andy wrote: “Cygnus is full of fun stuff to shoot. I had no idea how large the area surrounding the central star of Cygnus (Sadr or Gamma Cygni) was. The large area around Sadr is identified as the Sadr Region or the Butterfly Nebula, IC 1318. This was shot at 300mm. At some point I am going to have to zoom in the Crescent Nebula, NGC 6888 (far right center), for a closer shot of that. I would also like to figure out how to bring the reds out more. What fun.” Thank you, Andy!

North America and Veil nebulae

The North America Nebula, or NGC 7000, lies a little over three degrees east of Deneb. When you look at it in photos, can you trace out the shape of the continent for which it’s named? You can glimpse this large nebula under dark skies with binoculars. In fact, it extends up to four moon-widths. As a matter of fact, depending on your vision and sky conditions, you might detect this large 4.4 magnitude nebula with your eyes alone.

You can also use binoculars to see the Veil Nebula, or NGC 6992. The Veil Nebula spans a big sweep of sky just south of Epsilon Cygni, the eastern star in the Swan’s wing. This entire region is the Cygnus Loop and consists of the remains of a star that exploded in a supernova 5,000 years ago.

Large clouds of red nebulosity behind a foreground of stars.
View at EarthSky Community Photos. | Jeremy Likness in Monroe, Washington, captured this view of the North America Nebula in Cygnus on August 1, 2022. He wrote: “NGC 7000, the North America nebula, is bright, massive, and high in the sky this time of year. I framed it to show its namesake.” Thank you, Jeremy!

Cygnus is great to explore with binoculars

In addition to the objects mentioned above, you can explore Cygnus in binoculars. That’s because the Milky Way makes a rich background in this part of the sky. So you can find many more nebulae and clusters if you’re patient and sweep the area with binoculars or a telescope.

Bottom line: Cygnus the Swan is a constellation that lies atop the Milky Way. Also, its brightest star, Deneb, is part of the Summer Triangle.

Read more: Why 61 Cygni is nicknamed Flying Star

Posted 
July 5, 2023
 in 
Constellations

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