The Andromeda Galaxy — catalogued as M31 — is the most distant object visible to the naked eye, sitting roughly 2.5 million light-years away. On a clear, dark night it appears as a faint smudge near the constellation Andromeda, and finding it is a rite of passage for new astronomers.
What you need
- A dark sky with limiting magnitude of at least 5.0
- Your eyes (dark-adapted — give them 20 minutes away from screens)
- A basic star chart or the free Stellarium app
The hop
Start at the Great Square of Pegasus — four bright stars forming a large square high in the autumn sky. From the top-left star (Alpheratz), count two stars along the chain toward the northeast. That is the star Mirach. From Mirach, hop north-northwest to a fainter star, then continue the same distance again. You are now looking at the core of Andromeda.
Tips
Use averted vision — look slightly to the side of where you expect the galaxy to be. The edges of your retina are more sensitive to faint light than the centre. The galaxy will appear as a soft, elongated glow about three times the width of the full Moon.
Patience is everything. Find a comfortable position, let your eyes settle, and give the sky time to reveal itself.