History of the Constellations

Stars and Constellations

Andromeda

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

Images (at bottom of page): | Andromeda Chart: (Figure 1) | Hyginus, 1482, page 1r: (Figure 2) | Hyginus, 1482, page 1v: (Figure 3) | Hyginus, 1517, page F1r: (Figure 4) | Ptolemy, 1541-const, page Andromeda: (Figure 5) | Bayer, 1661, page U: (Figure 6) | Bayer, 1697, page G2v: (Figure 7) | Bayer, 1697, page G3r: (Figure 8) | Bayer, 1697, page G3v: (Figure 9) | Bode, 1801, page l: (Figure 10) | Bode, 1801, page r: (Figure 11) | Aspin, 1825, page Andromeda: (Figure 12) | Images digitized by Hannah Magruder.

Constellation Data

Description

Andromeda contains one corner of the Great Square of Pegasus (the star Alpheratz). Andromeda’s dress flows outward from the corner along three pairs of stars, with each pair slightly farther apart than the previous pair. Perhaps she is petting Pegasus, who bore the hero Perseus across the ocean on his mighty wings to save her from the sea monster Cetus.

Skylore and Literature

Andromeda (An-DRAW-ma-duh) is named for the daughter of King Cepheus and Queen Cassiopeia of Ethiopia. When Cassiopeia boasted that Andromeda’s beauty exceeded that of the sea nymphs, the nymphs prevailed upon Neptune, the god of the sea, to punish Cassiopeia. Neptune sent the sea monster Cetus (sometimes known more favorably as simply a whale) to ravage the kingdom of Cepheus. When Cepheus consulted an oracle for advice, he was informed that only the sacrifice of Andromeda to Cetus the Sea Monster would appease the gods. Thus chained to a rocky cliff, she was rescued by Perseus, who turned Cetus into stone by flashing the face of Medusa before the monster’s eyes. Perseus was carried there just in time by the winged horse Pegasus. (This story is retold in the film "Clash of the Titans.") All of these constellations are located in the same region of the sky, as noted in the following poem.

Cicero, De natura deorum, II.110, trans. of Phenomena by Aratos of Soli (ca. 220 B.C.): Cassiopeia with her obscure stars, | And next to her roams a bright shape, the sad | Andromeda, shunning her mother’s sight. | The belly of the Horse touches her head, | Proudly he tosses high his glittering mane; | One common star holds their twin shapes joined | And constellations linked dissolubly.

Modern Culture

Origin and History

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

Asterisms

  • Baseball diamond (with Pegasus)
  • Great Square
  • Frederick’s Glory (Honores Friderici)

Special Stars

Alpheratz means the navel of the horse, and recalls a time when the star was assigned to the constellation Pegasus. The star that is now Alpha-Andromedae was once Delta-Pegasi. Magnitude: 2.1. Distance: 72 LY.

Galaxies

On one side of Andromeda’s dress is a wedding present from Perseus, a patch of light called M31 or the Andromeda galaxy. The great galaxy in Andromeda shines at mag. 3.5. This beautiful spiral galaxy is the most distant object visible to the naked eye, yet the closest major galaxy to the Milky Way, about 2,200,000 light years away. (Figure 13)

Nearby are two small satellight galaxies, M32 (Elliptical galaxy), mag. 8.2. The other is NGC 205 (Elliptical galaxy), mag. 9.4.

Now, all the stars that are visible to the naked eye lie within our own Milky Way galaxy. This means that the stars that make up all the constellations, including Virgo and Leo and Coma Berenices, are stars of our own galaxy. The galaxies we see in these constellations are not actually located in the constellations, they are only viewed along the same line of sight. Were we to actually go to another galaxy, even the Andromeda galaxy (which is the closest major galaxy to the Milky Way, only 2.2 million light years away), then the stars of the Milky Way would not be distinguishable. It makes no sense to talk of Andromeda or Virgo as seen from another galaxy, since from another galaxy any observer would see all of the Milky Way stars together, just as we see a small patch of fuzzy light when we look at the Andromeda galaxy. It is not that Andromedans would see our constellation Andromeda differently; they would not distinguish it from the Milky Way at all.

The Andromeda galaxy has been known from early times. Al-Sufi described it as a "little cloud" in 964 AD. Simon Marius observed it in 1612 through a telescope, and described it as like a flame of a candle. It was not easy for astronomers to understand what a galaxy looks like. Early viewers of the Andromeda galaxy did not imagine that it was a star system like our own. Christian Huygens (HOY-gens) thought it was a hole in the heavens through which we might peer into the luminous regions beyond. Edmond Halley agreed, suggesting that the light came from a region of perpetual day, a shining ether filled with the light that originated on the first day of creation, before the formation of the Sun, Moon and stars. In 1845 Lord Rosse, using his great reflecting telescope, first resolved it into stars. In the 1920s Edwin Hubble--using the 100-inch telescope at Mount Wilson--used Cepheid variable stars to show that the Andromeda galaxy lay beyond the Milky Way. Thus Hubble established that the "nebulae" or cloudy spots which could be resolved into stars are actually external galaxies.

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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And Chart
Figure 2 Figure 2 - Return to Text

Hyginus, 1482

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Hyginus, 1482

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Hyginus, 1517

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Ptolemy, 1541-const

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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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Bode, 1801

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Aspin, 1825

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M31

Image credit: NOAO/AURA/NSF

Exhibit credit: Kerry Magruder.

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

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