M39
Where is M39?
Look south, about 87° up at 21:38 in Cygnus.
- Rises
- Always up
- Highest
- 21:35
- Sets
- Never
- Best after dark
- 21:38 · 87°
Can I see M39 tonight?
From London tonight, M39 is above the horizon all night. It’s highest after dark at 21:38, in the south at 87°.
At magnitude 4.6, with its light spread out, it needs binoculars and a dark sky.
This is position and timing only: clouds, haze and light pollution aren’t included.
What does M39 look like?
Eyes
Under dark skies, a faint brightening in the Milky Way.
Binoculars
A loose triangle of bright stars, the best way to see it.
Telescope
Use the lowest magnification; at higher power the cluster spreads out beyond the field.
About M39
M39 is a large, loose open cluster in Cygnus, about 1,000 light-years away. It contains a few dozen bright stars arranged roughly in a triangle.
It lies in a rich part of the Milky Way, so it can be hard to tell where the cluster ends and the background stars begin.
M39 is a few hundred million years old. About 30 stars stand out against the rich background of the Cygnus Milky Way, which can make the cluster look larger and looser than it is.
Charles Messier added it to his list in 1764. A few degrees to its southeast, a long dark lane of dust called Barnard 168 leads toward the faint Cocoon Nebula, a target for dark skies and larger telescopes.
Because it is so close to Deneb, M39 is high overhead on late-summer and autumn evenings from mid-northern latitudes, a good time to sweep for it.
Nearby in the sky
Questions
Is M39 better in binoculars or a telescope?
Sources: SkyMate; star chart: Wikidata (CC0). Positions computed for your place and time with astronomy-engine. Data & Licences