Constellation - Andromeda

Constellation - Andromeda


Andromeda is a large constellation in the northern hemisphere. It was described by Ptolemy in his original 48 constellations. The constellation is visible if you are north of 40 degrees South latitude. This constellation is easy to recognise once you identify the large square of Pegasus. It contains M31, the Andromeda galaxy. This is the nearest galaxy to us and can be seen with the naked eye on a dark night.

Andromeda is home to the Andromedids meteor shower that peaks around August 31st and reaches a maximum of around 20 meteors per hour. Its worth watching for as sometimes you can observe red fireballs.


Andromeda was the daughter of Cassiopeia and Cepheus. Cassiopeia's vanity caused her to anger the sea nymphs. Poseidon was so angry he threatened to destroy their lands and so, Cassiopeia tied her daughter to a rock as a sacrifice to Cetus the sea monster. Luckily, Perseus came to her rescue and demanded that Andromeda should become his wife. Cassiopeia and Cepheus agreed.

Take the Tour:

Number Object Description Magnitude Surface Brightness
1 M31 Galaxy 3.4 13.5
M32 Galaxy 8.1 12.4
M110 Galaxy 8.1 14
2 C17 Galaxy 9.5 14.5
C18 Galaxy 9.2 14.3
3 M76 Planetary Nebula 10.1 10.4
4 C23 Galaxy 9.9 13.6
5 M34 Open Cluster 5.2 n/a
6 C28 Open Cluster 5.7 n/a
7 M33 Galaxy 5.7 14.2

Each image is the size of a full moon for size comparison.

M31, The Andromeda Galaxy:


Messier 31, the Andromeda Galaxy is one of the wonders of the night sky that is not to be missed. Visible to the naked eye on a dark night and easily located. This galaxy has a bright nucleus but its surface brightness is low as the galaxy is large and so, the light it emits is spread over a large distance. This is a spiral galaxy and is the largest in our local group containing over double the number of stars found in the Milky Way at about 1 trillion. It is found 2.5 million light years away, pretty amazing to think that it is visible to the naked eye from this distance. This galaxy is our nearest galactic neighbour and on a collision course for the Milky Way. Although, the collision isn't expected for 3 billion years, but just imagine the view of the night sky as it approached. First discovered in a telescope by Simon Marius in December 1612.

M32, Le Gentil:


Messier 32 is an elliptical galaxy that neighbours Andromeda 2.65 million light years away. It was discovered in October 1749 by Guillaume Le Gentil by which it takes its name. Latest research seems to suggest that this was once a spiral galaxy but the tidal forces from nearby Andromeda stripped away the arms and left the central bulge. This may explain why it has very little gas and dust and hence, almost no star formation. You can find this galaxy just south of M31. Could this be the fate of our galaxy in 3 billion years when we collide with Andromeda?



Messier 110 is a dwarf spheroidal galaxy found 2.9 million light years away and northeast of M31. Although included in a diagram of M31 by Charles Messier in August 1773 it wasn't until 1967 before it was included in the Messier catalog and is the last entry. This galaxy is unusual for its class as it exhibits new stellar activity. This galaxy is just visible in binoculars on a dark night and can still be seen with a telescope in mild light pollution. Although, this is a great challenge for the backyard observer.



Caldwell 17 or NGC 147 is a dwarf spheroidal galaxy found about 2.6 million light years away and is another member of Andromeda's satellite group. It was discovered by John Herschel in September 1829. This is a faint galaxy to spot and harder to see than it's neighbour C18.



Caldwell 18 or NGC 185 is a dwarf spheroidal galaxy 2.1 million light years away. Discovered by William Herschel in November 1787. It is yet another satellite galaxy of Andromeda. This galaxy is easier to see than it's neighbour Caldwell 17.

M76, The Little Dumbell Nebula:


Messier 76 is a challenge. Some suggest that this is one of the faintest Messier objects. You will need dark skies for this one with a small telescope. It is a bipolar planetary nebula and lies 2,500 light years away. It was discovered by  Pierre Mechain in September 1780. It is called the Little Dumbell nebula as it is like the little sibling of the larger Dumbell nebula found in Vulpecula.



Caldwell 23 or NGC 891 is a barred spiral galaxy. It is found about 27 million light years away. This is a lovely edge-on galaxy to observe due to its clear dust lane that can be seen with larger telescopes. It was first discovered by William Herschel in October 1784.



Messier 34 is an open cluster that is quite easy to spot and locate. You know you have found it when you see its distinctive 'X' shape. This open cluster is probably older than the Pleaides but younger than the Hyades open clusters. It is found 1,500 light years away and was discovered before 1654 by Giovanni Batista Hodierni. 



Caldwell 28 or NGC 752 is an open cluster 1,300 light years away. It was discovered by Caroline Herschel in 1783. This open cluster can sometimes be seen with the naked eye on a particularly dark night.

M33, The Triangulum Galaxy:


Messier 33, the Triangulum galaxy is an unusual object to see and notorious amongst amateur astronomers. You can spend hours looking at the right area in the sky and not see it, even though it is magnitude 5.7, and some people will tell you it is visible to the naked eye. The problem is this galaxy is a big object and the light is fairly evenly spread across the whole surface. This makes it much harder to see if any light pollution or moonlight exists in the sky. Under perfect sky conditions it is one of the furthest objects that can be seen by the naked eye at 3 million light years away. The best chance to observe this galaxy is to make sure you are zoomed out as far as you can go with your telescope. Use your lowest power eyepiece and try averted vision. This galaxy was discovered by Hodierna before 1654.

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