This entry is part of the h2g2as constellations
project.

There exists an external provisional star chart created for this entry.

The northern constellation of Andromeda is a large constellation that
was listed by Ptolemy as one of the 48 original constellations handed down from antiquity. It is at its most prominent during late autumn and winter months when it can be seen to the south of the prominent W of Cassiopeia. The great square of Pegasus is to its west, and it is bounded by Perseus to its east. Andromeda appears as an elongated Vee with the two chains of its principle stars coming to a common apex at
its brightest star α Andromedae Alpheratz. The two arms of the Vee extend north-east with the more southerly of the two comprised of the brighter stars, ε, δ, β and γ. The northerly arm extends through π, μ and 51 Andromedae.

Mythology

Andromeda, the Chained Lady, was the daughter of King Cepheus and Queen Cassiopeia of Aethiopia.(Not the modern day Ethiopia) The vain queen Cassiopeia offended the sea god Poseidon? when she boasted that she and her daughter's beauty was greater than that of the sea nymphs, the Nereids, who were the hand maidens of Poseidon. Poseidon sent a sea monster, Cetus, to ravage the coast of the kingdom as punishment for her vanity. To bring an end to the monster's deprivations, King Cepheus went to the Oracle of Ammon for advice and was told to sacrifice his daughter Andromeda to the sea monster to placate Poseidon.

Andromeda was duly chained to the rocks on the coast for the monster to devour. She was saved at the last moment by the hero Perseus, riding in on his winged horse Pegasus. Perseus turned the monster to stone with the look from the head of the Gorgon Medusa who he had recently slain.

Principle Stars

α Andromedae Alpheratz, also sometimes known as
Sirrah, was originally part of the adjacent constellation Pegasus until the International Astronomical Union (IAU), reorganised and consolidated constellation boundaries in 1930, when it was assigned to Andromeda as its principle star. Consequently the meaning of its name, 'The Horses Navel' has an equine flavour which is hardly in keeping with a 'Chained lady'. Nevertheless, Alpheratz is still
recognised as the north-eastern corner of the 'Great square of Pegasus' and is magnitude 2.06 at 120 light years distant.

β Andromadae Mirach, 'The Girdle' is at the waist of Andromeda and is reddish in hue at +2.06 magnitude. It has a 14th magnitude dwarf companion and is 75 light years distant.

The meaning of γ Andromedae's name, Almach, which marks one of the lady's feet, originates in early Arab astronomy. It refers to a small Arabian mammal, similar to a badger but has little connection with the Greek legend. It is however, one of the finest, coloured double stars in the night sky. It requires a small telescope to separate its components into a primary red/orange and a blue/green
secondary. William Herschel commented of it: 'This double star is one of the most beautiful objects in the heavens. The striking difference in the colour of the two stars suggest the idea of a sun and its planet.'

Undoubtedly, one of the night skies showpiece stellar object, M31 (NGC224), the Great Spiral Galaxy, lies in Andromeda and is one of the best known. It is visible to the naked eye on a clear night and is seen as a light fuzzy patch and at 2.2 million light years distance it is generally accepted as the most remote object that can be seen with the unaided eye. Its size is almost three and a half degrees,
and encompasses an estimated 300 billion stars.

It can be found by star-hopping along the northern chain of stars from Alpheratz, through π and μ And, then north-east about four degrees where it will be found adjacent to ν And. If you can wait for a while, you may get a much better view of it, as it is heading this way and is due to collide with our own Milky Way in about three
billion years.

The Great Spiral Galaxy is accompanied by M32 (NGC221) which lies about a half of a degree to its south and another companion galaxy, M110 (NGC205) about one degree to the north-west. Both of these require binoculars or a small telescope to be seen.

Meteor Shower

The Andromedids or Bielid Meteors have a radiant point near γ Andromedae in mid November and are named from the comet discovered by the astronomer Biela in 1826. Their path does not cross the Earth's orbit annually, consequently they are not seen each year. The Bielids produced some spectacular showers during the 19th century, notably in 1827 and 1885, but after the break up and disappearance of the parent comet, showers became less prolific to the point of near
exhaustion. They orbit in the same direction as the Earth and produce apparently slow trains of orange sparks, but their frequency is currently down to only a few per hour.

Stars, Clusters, and Nebulae