I have some news to to share. And I suggest you take this lying down. Literally. The next clear night, sprawl on your back and look straight up. Almost directly overhead you'll face a swan of stars slowly winging by. Say hello to Cygnus, a star pattern recognized since antiquity. Greek astronomer Claudius Ptolemy included it his list of 48 constellations around the year 150 A.D.
Cygnus is one of the few constellations that's obvious even from a relatively light-polluted sky. Deneb, its brightest star, marks the tail of the swan. Its name comes from "dhanab," the Arabic word for tail. The stars Sadr and Albireo frame the bird's body and long neck, while Epsilon and Delta Cygni extend outward to form a pair of wings. I'd say the ancients did a pretty good job creating a reasonable facsimile of a swan using just five stars!
As with nearly all the 88 constellations your imagination provides the rest. Those same five suns also form one of the sky's best known asterisms — the Northern Cross. Here, Deneb becomes the head of the cross, the wings the crossbeam and Albireo its foot. Like flipping a switch on and off it's easy to picture both simply by shifting your perspective and seeing the figure "in reverse." Cygnus illustrates that two different points of view can be equally valid.
Everyone oohs and aahs over the Southern Cross. Yes, it's got three brilliant stars the likes of Deneb. Yes, it's compact and cute. But it barely looks like its name — more like a kite — while the northern version shouts cross. Cygnus represents Zeus, the king of the Greek gods, who disguised himself as a swan to pursue the nymph Nemesis for yet another of his frequent love affairs.
You can start your own love affair with the constellation by cupping your hands behind your head the next clear night and looking straight up. For a real treat, bring a pair of binoculars and slowly sweep up and down the constellation from a dark sky. The Milky Way passes directly through Cygnus, so the entire cross throbs with stars. Binoculars will show hundreds especially between Albireo and Sadr, the location of a dense patch of starlight called the Cygnus Star Cloud. You won't believe your eyes.
Deneb is one of the brightest, most distant stars visible with the naked eye. Shining at 1st magnitude, it's about 2,600 light-years away. From to time, I enjoy using stars as time machines to travel back into the past. When it comes to Deneb, the light we see now left the star when Nebuchadnezzar II built the famous Hanging Gardens of Babylon. Far out!
Its next-door neighbor, Vega, shines more brightly, but it's a mere 25 light-years distant. Deneb only appears diminished because of its enormous distance, when in fact it's one of the brightest stars in the galaxy — a supergiant about 108 times the diameter of the sun and nearly 200,000 times as luminous. If you could haul Deneb to Vega's distance it would shine at magnitude -9 (40 times brighter than Venus) and cast shadows. Stars as massive as Deneb will expand to become red supergiants and ultimately collapse and detonate as supernovae.
Cygnus also houses Albireo, one of the sky's finest and most colorful double stars for small telescopes, and the Veil Nebula, a spectacular supernova remnant. You can split Albireo in even a small scope. For the Veil, you'll need a 6-inch or larger telescope to reveal the expanding cloud of glowing gases left in the wake of a massive stellar explosion that occurred some 10,000 years ago.
Life is so short on the astronomical scale. As the swan flies past, enjoy every nanosecond.
"Astro" Bob King is a freelance writer for the Duluth News Tribune. Read more of his work at duluthnewstribune.com/astrobob.