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Cygnus

(SIG-nuss)

The Swan

Cygnus, the Swan, points southward along the summer Milky Way, a good marker when that glowing band of stars is hidden by a light-polluted city sky. The bright stars connected with blue lines (see map) are also known as the Northern Cross. 

Visibility: At 8 PM Standard Time (9 Daylight Saving Time) Cygnus is low in the northeast in early June, rising throughout the summer to be high overhead in late September. The constellation then lies low in the northwest in early January before being lost to the sunset in February.

What to look for: The very bright star Deneb (Alpha Cygni) is the tail of the Swan, or the top of the Cross. Sadr (Gamma Cygni) marks the Swan's body, and the bird's long neck stretches clear down to Albireo (Beta Cygni), the head of the Swan, or the foot of the Cross. One wing extends to the joint at Delta Cygni, and out to the tip at Iota Cygni. The other wing reaches past the joint at Gienah (Epsilon Cygni) to Zeta Cygni.


Mythology: Zeus (the Romans' Jupiter) was king of the Olympian Gods. On one occasion, he took the form of the swan - Cygnus - and seduced Leda, Queen of Sparta. That same night Leda also slept with her husband, King Tyndareus. Four children were born as a result, Polydeuces (Pollux) and his sister Helen, immortal children of Zeus; and their mortal half-siblings, Castor and his sister Clytemnestra. Polydeuces and Castor share their own constellation, Gemini, the Twins. Their fellow quadruplet Helen was none other than Helen of Troy, "she whose face launched a thousand ships," as Homer sang in the Iliad.

A Deeper Look: Albireo, the star at the beak of the Swan or the foot of the Northern Cross, is a beautiful blue and gold double star easily seen in a small telescope. 

Many nebulae and star clusters can also be found here, including the famous North America Nebula near Deneb, a great spread of hydrogen gas and darker, obscuring dust. Near Gienah is the Veil or Loop Nebula, the remnant of an ancient supernova.

North America Nebula
Photograph by Conrad Jung