How to find the Andromeda Galaxy
The easiest way to find the Andromeda Galaxy is to star-hop from the Great Square of Pegasus: from the square’s northeast corner, follow a chain of stars two steps east to the star Mirach, turn north past one fainter star, and continue about the same distance again. There, under a dark sky, you’ll see a faint, elongated smudge of light. It is best placed on autumn evenings from the Northern Hemisphere and is far easier with binoculars.
The Andromeda Galaxy, also known as M31, is a spiral galaxy roughly 2.5 million light-years away, and it is the most distant object most people can see without optics. The light you see left it long before modern humans existed.
Can you see it with the naked eye?
Yes, under dark skies. From a rural site with no Moon, Andromeda is visible to the unaided eye as a faint, fuzzy oval, often easiest to see with averted vision (looking slightly to one side of it). What you see is mostly the bright central region; the faint outer disk visible in long-exposure photos is far too dim for the eye.
From suburbs it is usually a binocular object, and from a bright city center it can be hard to see even with binoculars. That is not because the galaxy is faint overall, but because its light is spread over a large area, so it has low surface brightness and skyglow drowns it. If an app says it is “up” and you can’t see it, our guide on why you might not see something explains why.
When to look
Andromeda lies in the northern sky. From mid-northern latitudes it is visible at some hour for much of the year, but it is best placed, high in the sky in the evening, from about late summer to early winter, with autumn evenings the classic time. From far northern latitudes it never sets. From the Southern Hemisphere it stays low in the northern sky and is harder to see, and from far southern latitudes it never rises.
Choose a night when the Moon is down or a thin crescent (check the Moon phase calendar), wait until full astronomical darkness (the astronomical twilight tool gives the time), and look when the galaxy is high, away from horizon haze.
Route 1: from the Great Square of Pegasus
The Great Square of Pegasus is a large box of four moderately bright stars, high in the southeast to south on autumn evenings from mid-northern latitudes. Its northeast corner is actually the star Alpheratz, which belongs to the constellation Andromeda.
- Start at Alpheratz, the corner of the square nearest to Cassiopeia.
- Step east along Andromeda’s chain. Two roughly equal steps of similar-brightness stars lead away from the square. The second is Mirach, a moderately bright, slightly orange star.
- Turn toward Cassiopeia. From Mirach, look “up” toward Cassiopeia to a fainter star, Mu Andromedae.
- Continue the same distance again. Just beyond Mu, in the same direction, lies the galaxy: a soft, oval glow, a little longer than it is wide.
If you’re using binoculars, center Mirach, then move toward Cassiopeia through about two binocular fields: Andromeda should drift into view.
Route 2: from Cassiopeia
Cassiopeia is a W- or M-shaped group of five stars that is easy to recognize. The W has one deeper “V,” and the stars forming it point roughly toward Andromeda. Follow that line about three times the width of the V away from Cassiopeia and look for the faint smudge. This route is approximate but useful when Pegasus is low or hidden.
What binoculars and telescopes show
| Equipment | What to expect |
|---|---|
| Naked eye, dark sky | A faint, fuzzy oval; best with averted vision |
| Binoculars | A bright core in an elongated glow, often several Moon-widths long under dark skies |
| Small telescope, low power | The bright core and a fainter oval; companion galaxies M32 and M110 nearby |
| Larger telescope, dark sky | Hints of dust lanes along one side of the disk |
Two satellite galaxies are worth looking for: M32, a small, bright, compact glow close to the core, and M110, a larger, fainter oval a little farther away. Both are within reach of small telescopes under reasonable skies.
Use low magnification. Andromeda is large, and high power simply spreads its light across the field. Don’t expect the colorful spiral of photographs: to the eye, galaxies appear in shades of gray, and Andromeda is tilted steeply, so its spiral arms are hard to make out. Once you have it, try the nearby Triangulum Galaxy, M33, on the other side of Mirach: much harder, and a good test of a dark sky.