Andromeda Galaxy
What is Andromeda Galaxy?
Galaxies· Distance 2.5 million ly. The farthest thing you can see with your bare eyes — a trillion-star galaxy closing in at 110 km/s, destined to merge with the Milky Way in ~4.5 billion years.
📍 Visible from where you are right now — computed in your browser
bearing · altitude · rise time · best time tonight
Where Andromeda Galaxy is in your sky right now: https://nowsky.org/solar/sky?sel=andromeda galaxy — location and time set automatically, no login.
Its place in the sky
A galaxy, in the direction of Andromeda, spanning about 190 arcminutes of sky — 6.1 times the width of the full Moon.
Distance and scale
| Distance | 2.5M ly |
|---|---|
| Stars | ~1 trillion |
| Future | merges with us in ~4.5 Gyr |
Figures are representative approximations. Source: compiled from NASA and IAU public data.
Discovery and name
Recorded as a "little cloud" by al-Sufi in 964; in 1923 Hubble found a Cepheid here and proved it lies beyond our galaxy.
Frequently asked
- How far is Andromeda Galaxy from Earth?
- 2.5M ly.
- Where in the sky is Andromeda Galaxy?
- In the direction of Andromeda.
- In one line, what is Andromeda Galaxy?
- Galaxies — The farthest thing you can see with your bare eyes — a trillion-star galaxy closing in at 110 km/s, destined to merge with the Milky Way in ~4.5 billion years.
- Where is Andromeda Galaxy in the sky right now?
- Open the sky view for your location and time and it shows the position in the sky right now.
Six full Moons wide — so why does it look small?
The Andromeda Galaxy spans more than 3° of sky — six full Moons side by side. Yet to the naked eye or binoculars it appears only as a hazy oval about the size of one Moon, because the outer disk is far too faint in surface brightness for the eye to register and only the bright central bulge shows. The great spiral of photographs is light gathered by long exposures.
That is why composite images showing "Andromeda bigger than the Moon" are a camera's view, not an eye's. Under a dark sky away from cities, looking slightly to one side (averted vision) stretches the oval a little, and a 10 cm telescope reveals one dark dust lane crossing the disk. Even light that has travelled 2.5 million years reaches the eye only from the galaxy's core.
The galaxy in depth
Andromeda is the farthest thing human eyes can see unaided — 2.5 million light-years. The light reaching you now left when our ancestors were first shaping stone tools. Under dark skies it spans six full moons.
In 1923 Edwin Hubble found Cepheid variables inside this 'nebula' and measured its distance — proving the Milky Way was not the whole universe, but one galaxy in a sea of them. With a trillion stars, it out-counts our own.
It approaches at 110 km/s and merges with us in ~4.5 billion years into one giant elliptical — with essentially zero stellar collisions, because galaxies are mostly empty space. Find it in the autumn Sky view.
Andromeda's true nature broke in 1923, when Hubble measured a single Cepheid star inside it and proved it lay far beyond the Milky Way — in one stroke the universe grew from one galaxy to a sea of hundreds of billions. History's greatest zoom-out hinged on one star. In 4.5 billion years it will merge with our galaxy, though individual stars will almost never collide.
Related
Figures are representative approximations. Simulated positions use J2000 mean elements.