Andromeda


Andromeda


English nameAndromeda

Major
stars
alpha AndromedaeAlpheratzmagn. 2,1RA: 00h 08m 23.25sDec: +29 05' 25.9"
beta AndromedaeMirachmagn. 2,4RA: 01h 09m 43.91sDec: +35 37' 14.2"
gamma AndromedaeAlmachmagn. 2,3RA: 02h 03m 53.97sDec: +42 19' 47.1"
delta Andromedaemagn. 3,5RA: 00h 39m 19.68sDec: +30 51' 39.9"

DescriptionThe constellation of Andromeda is characterized by a double curved line of stars that departs from an angle of the Pegasus square and that forms the outline of a big wedge. It is easily found departing from Polar Star and crossing the constellation of Cassiopeia.

M31 The most remarkable object of the constellation is without doubt the great spiral galaxy M31: situated to around two millions light-years from us, it is the farthest of the naked-eye-visible heavenly objects. For a long time considered as a nebula, the galaxy of Andromeda was recognized only in 1924 by Edwin Hubble. If you observe it with simple binoculars, you can distinguish the two small galaxies that accompany it, M32 southerly and M110 northerly.

Among the interesting objects to observe with telescope, there is surely Almach a double system, composed by an orange giant and a small blue star, which is on its turn a double (but to separate its components, instruments of a certain power are necessary). Remarkable are also NGC 752, a big open cluster with more than one hundred stars of magnitude 9 and 10, and NGC 7662, one of the more easy planetary nebulas to observe with small instruments.


Mythology
and history
Andromeda was daughter of Cepheus and Cassiopeia. Cassiopeia pretended that her daughter was more beautiful than the Nereids and these, offensed, were complained with Poseidon, which sent a monstrous sea snake (represented by Cetus) to devastate the country. The oracle of Zeus in Libya affirmed that to get further such calamity, Andromeda herself had to be thrown to the monster. So she was chained to a rock to the feet of a stack: and in this position we can see her in the sky. But when the snake approached to devour her, Perseus attached it, showing the Medusa's head and so transforming it in stone.

Andromeda's head is represented by the star Alpheratz, the foot by Almach, the chained arms by the star lines which bring respectively to eta Andromedae (on the border with the Pisces) and to omicron Andromedae (near the constellation of Lacerta).


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