Cygnus the Swan (Submitted Graphic / <a href="http://www.dibonsmith.com/" target="_blank">Richard Dibon-Smith</a>)
Cygnus the Swan (Submitted Graphic / Richard Dibon-Smith)

High In the August evening sky there soars a trio of bright stars known affectionately to astronomers by the nickname of "The Summer Triangle." Each of these stars is the showpiece of its respective constellation one of which contains a well known asterism of naked-eye stars.

In alphabetical order, the Summer Triangle stars are named Altair, Deneb, and Vega.


All three star names are Arabian in origin, from a long ago time when that culture maintained the world's cutting edge in astronomy. Their constellations are Aquila the eagle, Cygnus the swan, and Lyra the harp, respectively. The names Aquila and Lyra originated in Italy and Cygnus comes from the French Cycnus.

Many myths and legends across multiple cultures are associated with these warm weather constellations. The famous Chinese legend "Night of the Sevens" involves two lovers, weaver girl and the cowherder represented by Vega and Altair, separated by an uncrossable and raging "River of the Sky" depicted by the Milky Way in the story.

Sometimes referred to as the Chinese Valentine's story the myth forms the basis for the annual Chinese Magpie festival aka. Double Sevens Day. The double sevens represent the 7/7 date in the Chinese lunar calendar which in 2016 corresponds to August 9.

According to star name expert Richard Hinckley Allen, a swan or hen image for Cygnus may have originated in Egypt's Euphrates River valley that runs through the modern countries of Syria and Iraq. The British ornithologist D'Arcy Wentworh Thompson has pointed out that swans were revered in ancient cultures for its hostility to other birds as well as beasts. Thomson's view was that Aquila and Cygnus viewed as a celestial battle with the eagle attacking the swan and losing as the eagle sets in the west before the Cygnus.

Embedded in the swan is a famous asterism. Asterisms are noticeable aggregations of stars that are not outright official constellations in their own right. An asterism known by various names over time including the Cross of Calvary and Christi Crux is the Northern Cross formed by six stars.

The head and foot of the four star vertical cross member (stipes) is marked by the stars Deneb (α Alpha) and Albireo (β Beta) with the stars Gamma (γ) and Eta (γ) between them. Gamma Cygni marks the meeting point of the stipes (pronounced STY-peez) and crossbar (patibulum) — whose endpoints are from west to east the stars Delta (γ) and Epsilon (ε).

Curtis Roelle is a member of the Astronomical Society. His website is www.starpoints.org, and he can be reached at starpoints@gmail.com.