How do I Find the Andromeda Galaxy (M31) with My Telescope?
Andromeda Galaxy, or M31, is the brightest of the Messier galaxies.
How is it so difficult to find with a telescope, then?
Is it a result of light pollution, or are you simply in the wrong place at the wrong time? Are you just looking at the wrong section of sky, perhaps?
Since Andromeda is one of the first deep sky objects an amateur will try to find, being unable to do so can be frustrating.
We at Love the Night Sky want you to can take in the glorious sight of M31 through a 6" telescope (or whatever you happen to be using. Heck, Andromeda galaxy through binoculars will bring you a glow of pride and awe when you first find it!). So, we've written this article to help you find the Andromeda Galaxy.
What is the Andromeda Galaxy?
The Andromeda Galaxy is a member of the Local Group of galaxies, the same group that our own home galaxy, the Milky Way, is in. As mentioned before,
Although it's 2.5 million light years away from us, it's so bright that you can see Andromeda with the unaided eye from a dark enough site.
When it comes to urban areas, however, light pollution means you'll only see M31 through a telescope, even then, you'll only see its bright core.
M32 is just south of Andromeda’s nucleus, while M110 is to the northwest. These two are the nearest bright elliptical galaxies, while farther away are NGC 147 and NGC 185 in Cassiopeia. Here you can see a sketch of Andromeda (M31), M32, and M110.
For the rest of this article though, we'll focus on finding the Andromeda Galaxy itself.
Where is the Andromeda Galaxy?
You won't be surprised to learn that the Andromeda Galaxy is found in the constellation of Andromeda.
It's best to find Andromeda in fall in the Northern Hemisphere, where it can be seen from dusk until dawn.
In late September and early October M31 rises in the eastern sky. It's overhead around midnight and still high in the west as it fades into the morning's dawn glow.
One of the hardest things about locating Andromeda Galaxy for the first time is knowing what to expect.
It certainly does not look like this image (and many others you're used to seeing) and it's nowhere near as bright as the stars nearby.
With the unaided eye, Andromeda is a hazy patch of light in the sky, about as wide as the full moon would be. You may even mistake it for thinking your eye is a bit blurry... a gray smudge on sky is perhaps the best way to describe it.
Click on the screenshot from Stellarium (free astronomy software)
Finding M31 With Alpheratz and Mirach
One way that you can find Andromeda is to use Alpheratz (Alpha Andromedae) and Mirach (Beta Andromedae).
Click the image below to enlarge it, and you will see Alpheratz and Mirach in the lower middle section. You can do this by
Use your viewfinder to hop down two stars northeast from Alpheratz to Mirach, and then go northwest two stars to Nu Andromedae. The Andromeda Galaxy is 1.3 degrees west of Nu Andromedae.
That's close enough that you will be able to see both objects in your viewfinder at the same time.
If you use a wider-angled eyepiece to get M31 in your sights, you'll be able to see both it and Nu Andromedae in the same eyepiece view.
Mirach and Alpheratz also create a nearly-right triangle with Andromeda. M31 lies about 8° northwest of Mirach, and 14° northeast of Alpheratz. If you need a better visual reference, take a look at this finder chart.
Finding the Andromeda Galaxy with Cassiopeia
Click on the image above to expand it, and notice Cassiopeia is towards the top left.
Cass is perhaps the easiest constellation to find in the night sky after the Big Dipper. For most of us, it's also a circumpolar constellation, which means it's out all night and so a reliable sight.
Find the Andromeda galaxy using Cassiopeia by joining Shedir (Alpha Cassiopeiae), Caph (Beta Cassiopeiae), and Navi (Gamma Cassiopeiae) in a triangle.
Shedir is the star at the southernmost point of Cassiopeia. In the triangle you've imagined, Shedir points towards M31 in a southwest direction, about 15° away.
A helpful finder chart is here for this method.
Andromeda Galaxy in a Telescope
While M31 can be seen with the naked eye, it is just an uninteresting haze.
For a more detailed view use a telescope. Any beginner telescope will be able to see the Andromeda galaxy (you can be it with binoculars, but there is less detail).
A good star chart is also recommended, but the star finders above will work just fine. We recommend printing one of them out on a large scale, as small star finders can be difficult to compare to the vastness of the night sky.
We'd also recommend downloading Stellarium, which is free and fairly easy to use.
One absolute essential to finding M31 is a dark sky.
If you can, try and get away from light-polluted areas, which will obscure the edges of Andromeda and leave you only able to see the very core.
Light pollution does include moonlight, so pick a night when the moon is at the very end of waning, or the early beginning of waxing.
This video from ScienceOnline explains the methods discussed here more in-depth and with visual aids that you might find helpful (if you can get past the high school science class feel) in your search for the Andromeda Galaxy.
While M31 is the brightest galaxy visible in the northern hemisphere, it can still be hard to find.
Hopefully, this article will help you locate it in the dark of the night sky. Both methods we've shared are proven to work.
If you have any trouble finding the Andromeda galaxy, or just have something to say, feel free to comment below. Happy hunting!