Cygnus the swan is a summer constellation that is seen mostly in the summer sky between the latitudes of 90 degrees N and 28 degrees S. Cygnus is one of my favourite summer sky constellations as it appears to fly along the milky way in the sky, this constellation was the reason i first saw the milky way in my back garden; it was a fantastic guide to the milky way. Zooming in closer around Cygnus’ alpha star Deneb, the sky looks even more spectacular, I scanned Cygnus with my binoculars and saw so many stars and dust trails in the milky way, it was a truly amazing experience.
Deneb is part of the famous asterism, the summer triangle which is made up of 2 other stars along with Deneb; Altair in Aquila and Vega in the nearby constellation Lyra. out of the three stars Deneb seems the faintest as Lyra and Altair shine brightly and are only 16 and 25 light years away whereas Deneb is 1,500 light years away. Deneb is able to shine bright enough to be seen at the naked eye with this distance as it is a blue-white super-giant that’s luminosity is around 60,000 times more than the sun.
Cygnus contains many fascinating stars such as the famous double star, Albireo. These two stars are visible through a small telescope and are seen as a large golden star with a smaller blue dwarf companion. Albireo is at the opposite end of Cygnus to Deneb. Albireo has a magnitude of 3.2 and its dwarf companion has a magnitude of 5.1.
Cygnus is also home to many breathtaking deep sky objects visible through binoculars and small to large telescopes depending on the conditions present such as M39 which is an open star cluster which has a magnitude of 4.6 and contains around 30 stars which are a distance of 825 light years away. M39 is located north-east of Deneb. M39 should be visible with a good pair of binoculars or a small telescope.
There are two fantastic nebula’s that are located within the constellation of Cygnus; the veil nebula and the North America nebula. the veil nebula is a supernova remnant. It contains the dust and gases of a once large star, that died in a supernova explosion. Due to the extent to which these gases are spread, it has been suggested that the explosion took place between 5,000 and 15,000 years ago. These types of nebula’s are extremely faint and so they an only be seen with a large telescope. The North America nebula is located next to the star Deneb at the tail of Cygnus. This nebula is only visible due to the fact that the light from Deneb is illuminating its gases, otherwise it would be very hard to see. This nebula has a magnitude of 4.0 and therefore is visible through binoculars.
I know summer is over now, but Cygnus is still visible in the northern sky. look up high in the south-western sky and you should see it and as long as your light pollution levels aren’t too great, it should guide you to the milky way once you eyes have adjusted to the darkness.
- information on Cygnus and its features sourced from ‘stargazing for beginners’ ISBN: 978-1-4053-6195-8