History of the Constellations

Stars and Constellations

Cygnus

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Contents of this page: | Description | Skylore | Modern Culture | Origin and History | Asterisms | Special Stars | Star Clusters | Nebulae | Submit new info... |

Images (at bottom of page): | Cygnus Chart: (Figure 1) | Hyginus, 1482, page D3v: (Figure 2) | Ptolemy, 1541-const, page Cygnus: (Figure 3) | Kepler, 1606, page tp: (Figure 4) | Kepler, 1606, page X4v: (Figure 5) | Bayer, 1661, page I: (Figure 6) | Bayer, 1697, page D4v: (Figure 7) | Bayer, 1697, page E1r: (Figure 8) | Bayer, 1697, page E1v: (Figure 9) | Bode, 1801, page l: (Figure 10) | Aspin, 1825, page Lacerta: (Figure 11) | Images digitized by Hannah Magruder.

Constellation Data

Description

Find the bowl of the big dipper and locate the two stars nearest the handle. A line running through these stars, tracing away from it above the open bowl. This line runs to Deneb, the tail of the constellation Cygnus the Swan. With wings abreast, and long neck outstretched, Cygnus flies along the milky river.

Skylore and Literature

Zeus turned himself into a swan when he visited Leda, queen of Sparta.

One legend relates that the swan was the hero Orpheus, who enchanted all who heard him with his magic harp.

Another story relates this constellation to the story of Phaethon, a mortal who learned that his father was Helius, the sun god. Helius rashly promised to let Phaethon drive the chariot of the sun across the sky. Phaethon soon lost control, and his reckless driving threatened to destroy earth with the sun’s heat. Zeus intervened by hurling a thunderbolt at Phaethon, who fell into the Eridanus River. In his grief, Phaethon’s devoted friend Cygnus repeatedly dived into the water in search of the body. When Cygnus eventually died from exhaustion, Zeus took pity upon him and changed him into a swan, placing him into the sky.

Modern Culture

Origin and History

Cygnus is included in the ancient star catalogs of Eudoxos of Knidos, Aratos of Soli, and Ptolemy.

Asterisms

  • Summer Triangle: Deneb and two other bright stars form the "summer triangle," an asterism found high overhead all summer long amid the splendid sweep of the Milky Way. Deneb, the tail of the swan, is the northeast vertex of the Summer Triangle.
  • Northern Cross: Cygnus looks like a cross, where the crossbeam is the swan’s wings. Cygnus, its long neck stretched out, flies south for the winter along one of the brightest regions of the Milky Way. Around Christmas Eve at sunset the Cross stands upright on the northwest horizon.

Special Stars

Deneb (DEN-ebb) is a bluish-white supergiant, one of the most luminous stars known (about 60,000 times more luminous than the sun and 25 times more massive). Because it is so far away, Deneb appears to us as only the 20th brightest star in our sky. But if Deneb were as near as Sirius, which is our brightest star, then it would shine as brightly as the Moon. If Deneb were as close as Alpha-Centauri (four light-years away), we could read by its light.

Albireo (al-BEER-ee-oh), the beak of the swan, is one of the most beautiful of all double stars. In close proximity, one of the star-pair shines with a brilliant gold, and the other with a sapphire blue (examine Albireo on the color star chart below).

A small, massive object orbits a giant blue star near the center of Cygnus. Discovered in 1965 and known as Cygnus X-1, it cannot be seen with optical telescopes, but it emits intense, flickering x-rays. Most astronomers believe that Cygnus X-1 is a black hole. Matter from the bluish companion star spirals down toward the black hole, emitting x-rays as it reaches the boundary and disappears inside the black hole forever.

Star Clusters

M29 (Galactic cluster), mag. 8.0.

M39 (Galactic cluster), mag. 5.3.

Below the central star of Cygnus are clumps of stars that form the Cygnus Arm of the Milky Way galaxy. The Sun is located on the inside edge of the Cygnus Arm, about two-thirds of the way out from the galactic center. In a very real sense, then, our lives are closely linked with the stars of Cygnus. As Francis Thompson wrote:

All things by immortal power, | Near or far, | Hiddenly | To each other linked are, | That thou canst not stir a flower | Without the troubling of a star.

Nebulae

About 3 degrees to the east of Deneb is NGC 7000, called the North American Nebula because of its similar shape. A vast cloud of interstellar gas, it is an easy object for binoculars or a small telescope.

Submit new info...

Many excellent websites provide a variety of information about constellations for amateur astronomers and telescope users (see sidebar links for a few of these). These constellation pages are not intended to duplicate those efforts, but are devoted to two aims: First, they are intended to assist the beginning skywatcher, including students in history of science survey courses, in becoming familiar with Basic Celestial Phenomena (BCP). Second, these pages are devoted to the history of the constellations and the history of astronomy. They are intended to serve as a repository for collaborative use and reference. Do you have additional historical information about the stars or constellation described on this page? Please submit additional information to kmagruder@ou.edu. Submissions will be attributed. Editors for historical information are Kerry Magruder, JoAnn Palmeri, Peter Barker, and Laura Gibbs.

Oklahoma History of Science exhibits: http://hos.ou.edu/exhibits/. Page revised 4/15/04

Bad links, misplaced images, or questions? Contact Kerry Magruder. Thank you.

"If the stars should appear one night in a thousand years, how would men believe and adore, and preserve for many generations the remembrance of the city of God which had been shown. But every night come out these envoys of beauty, and light the universe with their admonishing smile." R. W. Emerson, Nature

Images

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Cyg Chart
Figure 2 Figure 2 - Return to Text

Hyginus, 1482

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Ptolemy, 1541-const

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Kepler, 1606

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Kepler, 1606

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Bayer, 1661

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Bayer, 1697

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Bayer, 1697

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Bayer, 1697

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Bode, 1801

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Aspin, 1825

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Exhibit credit: Kerry Magruder.

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These teaching resources provided by the History of Science Department at the University of Oklahoma.

Unless otherwise indicated, all images courtesy History of Science Collections, University of Oklahoma Libraries. Image Terms of Use.

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