Andromeda was the daughter of Cepheus and Cassiopeia. Mother thought
she and daughter were more beautiful than any of Poseidon's many nymphs,
and she taunted the God of the Seas until he just couldn't take it any
longer. Poseidon punished the vane mother by chaining her daughter naked
to a rock, to be sacrificed to a dreadful sea monster.
Some writers identify this monster with Cetus, another constellation.
But I can find no reference in the classical texts that directly name
the monster as Cetus. (In fact the very name means "whale", hardly a
dreadful sea monster.)
Perseus, fresh from slaying the Gorgon Medusa, was passing by. Attracted
by Andromeda's beauty, and no doubt the generally heroic opportunities
the situation offered, he agreed to rescue her. But only if he could marry Andromeda afterwards.
Cepheus and Cassiopeia were not anxious for their daughter to wed
Perseus, but they had little choice, so agreed. Perseus skimmed over
the water, thus confusing the monster, and then cut off the monster's
head. The wedding followed soon afterwards.
At the wedding relatives distrupted the proceedings, probably at
Cassiopeia's insistence. In the following melee both Cassiopeia and Cepheus lost their life. Poseidon put them both in the heavens (well, it was the least he could do...).
Much later Athene put Andromeda in the same region of the sky, between
mother and father.
The asterism consists of the brightest star,
Alpheratz (or Sirrah) denoting Andromeda's head, and
the rest of the principal stars marking other parts of the young woman's
body. But I like to think that the other stars in fact trace Andromeda's
flowing hair, and I've drawn the constellation to reflect that idea.
The Bayer stars are not very bright, as the
constellation generally ranges from third and fourth magnitude stars.
There are a number of fine binaries and several variables, and some very
nice deep sky objects, including perhaps the most famous spiral galaxy
Gamma1 and gamma2 Andromedae form a noted
binary with colour contrast, gold and blue.
The binary is a multiple system. AB: 2.5, 5; PA 63º, and
BC (the primary of which is gamma2) form a very close binary with
an orbit of 61 years: 5.5, 6.3; currently the
component is at PA 104º and separation 0.5"
Kappa Andromedae is a wide and rather faint binary: 4, 11; 194º,
Pi Andromedae is alse faint and wide: 4.4, 8.9; 173º, 36".
Tau Andromedae: 5, 10; 329º, 52.5".
Phi Andromedae has a 370 year orbit: 5, 6.5; 154º, 0.5".
Omega Andromedae: 5, 12; 122º, 1.9".
Zeta Andromedae is an EB variable: 3.9-4.1 with period of 17.77
Lambda Andromedae is an RS CVn type variable: 3.7-4.0, 54.2 day
Omicron Andromedae is a gamma Cas type variable, ranging from 3.6
R Andromedae: a Mira type variable with a period of 409.33 days,
ranging from 5.8 to 14.9. In 2000 the maximum should occur in April.
Deep Sky Objects:
One of Andromeda's greatest attractions is the spiral galaxy known as
M 31. There are also several more deep sky objects worthy of
M31 (NGC 224), "The Andromeda Galaxy", is the finest spiral
galaxy in the heavens, and probably the most well known.
The galaxy lies at about a fifteen degree angle from being edge-on; it
has a bright oval nucleus. Its distance is approximately 2.3 million
light years. Dust lanes become visible in medium-sized telescopes.
M32 (NGC 221) is the brightest elliptical satellite of M31,
although rather faint compared to the latter. This galaxy is located almost half a degree to the south of M31 and is best seen in large telescopes.
M110 (NGC 205) is another elliptical galaxy, and a larger companion to M31 but much dimmer. It lies about thirty-five arc-minutes NW of M31.
NGC 752 is an open cluster of perhaps a hundred rather scattered
stars. It's about four and a half degrees south of gamma Andromedae,
and two degrees west.
NGC 891 is rather faint, but quite a nice edge-on spiral with clearly distinguished dust-lane in large telescopes. It's four degrees due east of gamma Andromedae.
NGC 7662, sometimes called "Blue Snowball", this is a blue-green
planetary nebula with a very faint central star which is apparently
variable (estimated to range from 12 to 16 visual magnitude). The nebula
is found about 2.5º WSW of iota And.
For a closer appreciation of Andromeda, visit the Binocular Section.