[Andromeda]
[Front Page] [President's Report] [Martian Longhorns] [Points of Light] [Other Stuff] [News from the Beyond]


Andromeda


is one of a number of constellations that derive their names from the same epic Greek myth. Also from this story come Cepheus, Cassiopeia, Perseus and Pegasus, all in the same general region of the northern sky, as well as Cetus to the south. Andromeda is best known because it is home to the Great Nebula, M31, called the sister galaxy to our own Milky Way.

Although Andromeda occupies a large expanse of the night sky, it contains but six stars brighter than magnitude 4. And, ironically, the brightest of these, magnitude 2.1 Alpheratz, must be shared with the asterism of the Great Square of Pegasus as the northeast (upper left) corner. On some star charts it is still designated as Delta Pegasi.

The well known legend of the chained princess and her rescue by the hero Perseus is likely a reinterpretation of an even older story. The myth of a hero who slays a vile monster (Cetus) is the same as that of Saint George and the Dragon, of Marduk and Tiamet, of many a fairy tale. Andromeda may originally have been the dawn, whose beauty is released from the dark of night by the conquering Sun-hero.

The stories of Andromeda, the daughter of Cepheus and Cassiopeia, king and queen of Ethiopia, have been told for more than two thousand years, but the light that strikes your eye from the faint smudge that is the Great Galaxy has been traveling through space for more than two million years. If you have good eyes and a clear fall night without moonlight, M31 is the most distant object that can be seen without optical aid. Records show that this object was known to Persian philosophers in the tenth century and it was shown on fourteenth and fifteenth century Dutch and Spanish charts. But first mention of this celestial patch of light is credited to Simon Marius, who observed it with his telescope in 1612, even before the 1619 discovery of the conspicuous nebula in Orion. This was the time of the introduction of the first telescopes in Europe, and more and fainter such cloud-like visions were announced as the known world of astronomy expanded. By Herschel's time the perceived abundance of stars and the complexity of their distribution led him to suggest, in 1785, that a nebula might be a "stupendous sidereal system … consisting of many millions of stars … ." The English astronomer William Huggins offered proof of this theory in 1864, using spectrographic measurements. Not until Edwin Hubble, working with the newly completed 100-inch telescope at Mount Wilson in 1924, were photographic plates obtained that resolved the stars of the Andromeda Nebula and made certain that this distant pinwheel of light should be called instead the Andromeda Galaxy.

The Andromeda spiral NGC 224 (M31) is located 2.3 million light years from us, and is about fifty percent larger than our own galaxy. Find it about 13 degrees west of Gamma Andromedae, Almach, and an equal distance northeast of Alpha Andromedae, Alpheratz. It has a pair of companion galaxies, NGC 205 (M110) and NGC 221 (M32), as does our own Milky Way Galaxy, the Large and Small Magellanic Clouds (which may be observed only from the Southern Hemisphere).

An interesting edge-on spiral galaxy in Andromeda is NGC 891, located 40 million light years away. This CCD image, showing the prominent equatorial dark lane, was captured by Jim Scala. It is only of magnitude 12, but this fine object can be well observed with an 8-inch telescope if the night is dark, clear and moonless. It is located about three degrees east of Gamma Andromedae, or Almach, the second-magnitude star at the tip of the southern tine of the long, narrow V that identifies the constellation.

Almach is one of the finest of all double stars. Its primary star is a bright orange, with its double appearing as bluish or blue-green, separated by about 10 arcseconds. The secondary is itself a very close double star, but it is seen as a single star because the elongated orbit of its companion is generally not resolvable by telescopes. South-southwest of Almach is a large open cluster of stars that can be appreciated through a good pair of binoculars. This is NGC 752, whose stars are perhaps 1300 light years away. The star classifications indicate that they are at least one and a half billion years old. Another star of note is R Andromedae, a Mira-class variable star whose magnitude ranges from 5.1 to 14.8 over a period of 409 days.

There are a number of other multiple stars, variable stars, and other objects that lie in the direction of Andromeda, making it an important constellation in the night skies of autumn.


[Top of Page]
[
Return to EAS Home Page]