Andromeda Galaxy (M31)

Another whole galaxy — and you can see it with your own eyes. Its light has been travelling for two and a half million years to reach you tonight — and the whole galaxy is slowly heading our way.

Also called: M31, NGC 224.

🕒 When can I see it?🚀 Travel there

Andromeda Galaxy (M31) — Drawn, not photographed.

What it is

The Milky Way's larger spiral 'big sister', farthest thing most people can see with the naked eye.

Spiral galaxy: A flat disc of stars wound into arms. Ours is one. Every kind of thing there is →

How to find the Andromeda Galaxy

Look in the constellation Andromeda.

It is best placed in the autumn if you are north of the equator.

High and easy from northern latitudes; low or unreachable from most of the Southern Hemisphere.

The Planetarium works out where it actually is from your own place and the date — including whether it is above the horizon at all tonight.

Show me the Andromeda Galaxy in tonight's sky

What you will really see

With your own eyes

A faint fuzzy oval of soft light — the bright core shows; the arms only hint at themselves.

🔭 See it drawn as it looks through a telescope

🖨️ A sheet to print for this

🖨️ Print a sheet and go and look

🖨️ Sheet to take outside →

Worth knowing about the Andromeda Galaxy

The Andromeda Galaxy is ~220,000 light-years across vs. our ~100,000. On that same scale (Milky Way = 100-meter track), the Andromeda Galaxy would be about 2.5 kilometers away — a healthy bike ride past the finish line. Light takes 2.5 million years to get here from the Andromeda Galaxy, so what you are looking at is the Andromeda Galaxy as it was 2.5 million years ago.

What makes it worth knowing: Will merge with the Milky Way in about 4.5 billion years. Two satellite galaxies, M32 and M110, orbit it.
Its name and its story: Named for the mythological princess Andromeda, chained to a rock and rescued by Perseus — the constellation got the name first, the galaxy borrowed it.

How did anyone measure the Earth in the first place?

The numbers