Andromeda (constellation)

Full visibility (approx.):


  • Cassiopeia
  • Lizard
  • Pegasus
  • Pisces
  • Triangle
  • Perseus

The Andromeda (Greek Ἀνδρομέδα [ Androméda ] ) is a constellation of the northern night sky.

It is one of the more famous constellations, as it contains with M 31, where the Milky Way similar large Andromeda Galaxy, the closest spiral galaxy.


Andromeda consists of a chain of four stars emanating from the square of Pegasus. The three brightest stars Alamak, Mirach and Sirrah are almost on a line.

Under favorable conditions of observation is north of Andromedae a faintly luminous nebula can be seen, the galaxy M 31, also known as the Andromeda nebula known. The visible stars of the constellation itself belong to our galaxy and are no more than about 1200 light years away. The distance to the Andromeda Galaxy, however, is much larger, with around 2.7 million light years.


The Andromeda is one of the 48 classical constellations of the ancient world, described by Ptolemy.

It was named after Andromeda, a princess of Greek mythology.


Andromeda, the only daughter of the Ethiopian king Cepheus and Cassiopeia, should be sacrificed to a sea monster ( the whale ), which had been sent out to punish her ​​mother's vanity. Cassiopeia had claimed itself to surpass the Nereids in beauty. The so reviled turned to the sea god Poseidon, who sent a monster that devastated the coast of Cepheus ' kingdom. Only through the sacrifice of Andromeda could, as an oracle, the monster will be appeased. As Andromeda, chained to a rock, awaited their fate, the hero Perseus appeared with his winged shoes and slew the monster. As a reward he received Andromeda in marriage.

All figures of legend immortalized in the sky, the sea monster whale in the form of the constellation.

Another version brings the constellation with the cycle of legends about the hero Heracles in conjunction. After that, the stars represent the Amazon queen Hippolyte, whose belt had to procure Heracles.

Celestial objects

Brightest star

β Andromedae is a 200 light-years distant red giant with thirty times the diameter of our sun. The name Mirach is of Arabic origin and means as much as " loins ".

Double stars

The brightest star in the Andromeda is Sirrah ( α Andromedae ). It was originally attributed to the constellation Pegasus and carried the designation δPegasi. It is a binary star system in 97 light years away. The bluish- white luminous main star possesses the 110- times brighter than our sun. It is a variable star of type Alpha ² Canum - Venaticorum. He is accompanied by a faint companion star of the 11th magnitude.

The Arabic name Alpheratz and Sirrah derived from Surrat al - faras from, meaning " the navel of the horse " (with Ross Pegasus is meant ).

γ Andromedae is a 355 light-years distant triple star system. The glowing orange main star possesses the eighty times the diameter and 2,000 times brighter than our sun. He is accompanied by two bluish stars of the 5th magnitude, which together are very close. In a medium-sized telescope, the system can be resolved into two stars. This reveals a very nice color contrast between the yellow main star and the bluish companion stars, which can not be separated in the telescope. The Arabic name Alamak means " desert lynx ".

The 250 light years away And System 56 consists of two stars of spectral classes K0 and K4. The system comprises of the Earth from a wide distance of 200 arc seconds and can be detected already in binoculars as a double star.

59 And consists of two stars of spectral types B9 and A1. The system is 300 light years away from the Sun.

Variable Stars

R Andromedae is a variable star of type Mira, which changes its brightness over a period of 409 days. At the maximum, it reaches a brightness of 5.8 m and can be seen just under favorable conditions even with the naked eye. At a minimum, its brightness decreases to 14.9 m. Then, to watch him you need a larger telescope.

Messier and NGC objects

M31, the Andromeda galaxy is at a distance of about 2.5 million light- years, the next big spiral galaxy. You can already be seen with the naked eye as a misty patch and is probably known since time immemorial. In binoculars it appears as a vast oblong fog. In telescopes with large aperture (15 cm ) Star concentrations and dark dust bands are visible.

M32 is a smaller companion galaxy of the Andromeda nebula. In binoculars and small telescope it appears star-shaped.

M110 is another companion galaxy of the Andromeda nebula. It appears in the binocular and telescope as an elongated, misty spot. She was discovered in 1773 by Charles Messier.

The 1500 light years distant open cluster NGC 752 was discovered in 1786 by William Herschel. He can be seen with the naked eye as a misty patch. In binoculars it can be well resolved in 20 to 30 stars.

The 40 million light years distant spiral galaxy NGC 891 was discovered in 1783 by Caroline Herschel. From Earth, we see the galaxy in edge position, so that it appears as an elongated fog. In larger telescopes a central dust lane is visible.

The planetary nebula NGC 7662 was discovered in 1784 by William Herschel. It is the remnant of a star about 4,000 light-years away. In smaller telescopes it appears as a round, misty spot. In a telescope from four inches aperture, the object appears as a " smoke ring ".