Cotonou Stargazing & Astronomy Report
Light pollution and stargazing locations near Cotonou
- City
- Cotonou
- Country
- Benin
- Latitude
- 6.3654
- Longitude
- 2.4183
Key Sky Quality Metrics
- SQM (mag/arcsec²)
- 18.94
- Bortle class
- Class 7 (Class 7)
- Darkness Quotient
- 32%
- Dataset
- March 2026
Suburban/urban transition
Stargazing in Cotonou
Cotonou is Benin’s principal coastal city in the country’s south, a busy commercial hub on the Gulf of Guinea with a dense urban character.
The city generally experiences High Light Pollution, with a Darkness Quotient of 32% — placing it among the brighter urban skies, though not at the very harshest extreme seen in the world’s biggest megacities.
For practical observing from within the city, the most reliable targets are the Moon, bright planets, double stars and the brightest open clusters. Brighter showpiece deep-sky objects may be possible with care, but faint galaxies and the richer texture of the Milky Way are largely washed out by the urban glow.
Meaningfully darker skies are not right on the doorstep, but they are reachable with a moderate drive. The nearest really worthwhile step up is about 60 kilometres to the west, near Comé, Mono Department, where conditions improve to a good rural sky.
The map shows Cotonou embedded in a bright coastal chain, with intense red, pink and yellow cores marking concentrated urban lighting along the shoreline. Rather than an isolated light dome, the city appears as part of a broader ribbon of settlement, so the glow spreads laterally as well as upwards.
The darkest tones gather away from the brightest built-up areas, especially inland and over the open water to the south, where the map falls through blue into darker grey. That pattern suggests the strongest urban glare is tied closely to the coast and built corridors, while cleaner horizons begin to emerge once you get clear of that coastal belt.
Compared with its surroundings, Cotonou sits in one of the brighter zones on the map, though there are darker pockets and less intensely lit stretches not far beyond the main urban concentration. The overall picture is of a luminous coastal city with noticeably better skies available once you move away from the densest development.
What the sky overhead is like
Looking straight up from Cotonou, the zenith sits in Bortle 7 territory, which means the sky is clearly affected by urban light even away from the brightest horizons. The background will not look truly black, and contrast on faint objects is reduced.
You should still see the brighter constellations and the main stellar patterns without much trouble, but the dimmer linking stars are less secure and the sky can appear a little washed out. For casual stargazing this is still usable, though it is not a setting that shows the full richness of the night sky.
The result is a sky best suited to bright, high-contrast targets rather than delicate deep-sky observing. Looking overhead is noticeably better than looking into the more light-polluted horizons, but it remains an urban sky rather than a dark one.
north - fair
About 15 kilometres north of the city, the sky is fair, around Bortle 5, so brighter deep-sky objects begin to improve compared with the centre. If you keep going, genuinely dark skies are reachable at roughly 50 kilometres in this direction.
north-north-east - fair
At around 15 kilometres to the north-north-east, conditions are fair with a Bortle 5 sky. A much better step up arrives at about 50 kilometres, where this direction reaches genuinely dark Bortle 3 conditions.
north-east - fair
Around 15 kilometres north-east, the sky is fair at Bortle 5, giving some improvement but still leaving a noticeable glow. This direction does improve further, though the darkest conditions in the sampled range are not reached until about 200 kilometres out.
east-north-east - fair
At roughly 15 kilometres east-north-east, the sky is fair with a Bortle 5 rating. There is a useful improvement farther out, but genuinely dark conditions only turn up at around 200 kilometres in this direction.
east - marginal
About 15 kilometres east of Cotonou, the sky is marginal at Bortle 6, so city glow still has a strong influence. It does improve to good rural quality farther out, but genuinely dark skies are not reached within the sampled distance in this direction.
east-south-east - fair
Around 15 kilometres east-south-east, the sky is fair at Bortle 5 and already somewhat better than the city centre. A more substantial improvement appears by about 50 kilometres, where this direction reaches genuinely dark Bortle 3 skies.
south-east - fair
At around 15 kilometres south-east, conditions are fair with a Bortle 5 sky. Continue farther and this becomes one of the stronger directions, reaching genuinely dark skies at about 50 kilometres.
south-south-east - good
Roughly 15 kilometres south-south-east, the sky is already good at Bortle 4, making this a promising direction for a relatively short escape from the city. Push on to about 50 kilometres and it becomes genuinely dark, reaching Bortle 3.
south - good
About 15 kilometres south, the sky is good at Bortle 4, which is a clear improvement on central Cotonou. Farther out, genuinely dark conditions arrive at around 50 kilometres in this direction.
south-south-west - fair
At around 15 kilometres south-south-west, the sky is fair with a Bortle 5 rating. The direction improves well with distance, reaching genuinely dark Bortle 3 skies by about 50 kilometres.
south-west - fair
Roughly 15 kilometres south-west, the sky is fair at Bortle 5 and noticeably cleaner than the city itself. A more serious jump in quality appears at around 50 kilometres, where genuinely dark skies are reached.
west-south-west - fair
Around 15 kilometres west-south-west, the sky is fair with a Bortle 5 reading. This direction continues to improve and reaches genuinely dark conditions at about 50 kilometres.
west - marginal
About 15 kilometres west, the sky is marginal at Bortle 6, so the urban glow still lingers strongly. It becomes a good rural sky farther out, but genuinely dark skies are not reached within the sampled distance in this direction.
west-north-west - poor
At roughly 15 kilometres west-north-west, the sky is poor at Bortle 7, so this is not one of the better quick-drive directions. Conditions do improve substantially farther out, with genuinely dark skies appearing at about 50 kilometres.
north-west - poor
Around 15 kilometres north-west, the sky is poor at Bortle 7 and still heavily affected by light pollution. It does improve with distance, with genuinely dark conditions not arriving until roughly 100 kilometres out.
north-north-west - marginal
At about 15 kilometres north-north-west, the sky is marginal at Bortle 6, so there is only limited relief from the city glow. A much better improvement appears farther out, reaching genuinely dark skies at around 50 kilometres.
zenith - poor
Looking straight up from Cotonou, the zenith is poor for dark-sky observing, at Bortle 7 with an SQM of 18.94. The brighter constellations remain easy enough to trace, but the background sky is visibly bright and the faintest stars and subtle Milky Way structure are lost.
-
Near Tchaourou, Borgou Department
- Direction
- SSW
- Distance (km)
- 277
- SQM
- 21.69
- Bortle
- 3
Milky Way visible, broadband DSO imaging
-
Near Nkwanta South District, Oti Region
- Direction
- NW
- Distance (km)
- 280.6
- SQM
- 21.63
- Bortle
- 3
Milky Way visible, broadband DSO imaging
-
Near Comé, Mono Department
- Direction
- W
- Distance (km)
- 61
- SQM
- 21.09
- Bortle
- 4
Bright nebulae, galaxies, narrowband imaging
Genuinely dark skies require getting out of Cotonou rather than simply slipping to the edge of town. The nearest good step-change comes about 60 kilometres to the west at Near Comé, Mono Department, where the sky reaches Bortle 4 quality.
If you are prepared to travel much farther, truly dark rural skies become available at around 275 to 280 kilometres, with sites such as Near Tchaourou, Borgou Department and Near Nkwanta South District, Oti Region reaching Bortle 3.
-
Within 100 km
- Place
- Near Comé, Mono Department
- Direction
- W
- Distance (km)
- 61
- SQM
- 21.09
- Bortle
- 4
-
Within 500 km
- Place
- Near Tchaourou, Borgou Department
- Direction
- SSW
- Distance (km)
- 277
- SQM
- 21.69
- Bortle
- 3
How Cotonou’s skies have changed
The long-term pattern points to a gradual brightening of the night sky over time. Earlier measurements were darker, with the best readings reaching 19.73 SQM, while the latest figure stands at 18.94 SQM.
Across 75 datasets, the average sits at 19.25 SQM, and the trend works out to roughly -0.04 SQM per year. That is not a dramatic collapse from one year to the next, but it does suggest a steady increase in skyglow over the longer term.
In practical terms, this means the city has likely become a little less forgiving for faint-object observing over the past decade or so. Bright targets remain rewarding, but the margin for seeing subtle detail has narrowed.
From within Cotonou, the best targets are bright and contrasty ones that can cut through the skyglow. The Moon and planets are the obvious highlights, with double stars and a few bright open clusters also holding up reasonably well.
A handful of brighter deep-sky showpieces can still be attempted, especially with careful observing and some shielding from local lights. Even so, they will look more subdued than they would under a darker rural sky.
For the Milky Way, faint galaxies, large diffuse nebulae and meteor watching, a trip away from the city makes a major difference. Those are the kinds of targets that benefit most from the darker sites outside Cotonou.
- Moon
- planets
- double stars
- brightest open clusters
- bright nebulae such as M42
- the brightest globular clusters
- Milky Way
- faint galaxies
- broadband nebulae
- meteor showers
Can you see stars from Cotonou?
Yes — you can certainly see stars from Cotonou, including the brighter constellations and the more obvious patterns overhead. What you lose is the fainter background population, so the sky looks less richly packed than it would from a rural site.
Can you see the Milky Way from Cotonou?
From the city itself, the Milky Way is generally very difficult to see well under a Bortle 7 sky. You would need to travel away from the urban glow for a much more convincing view.
What Bortle class is Cotonou?
Cotonou is Bortle 7, which is a suburban-to-urban transition sky. In practice that means bright objects still show well, but faint deep-sky observing is heavily limited by light pollution.
What is the SQM in Cotonou?
The measured sky brightness is 18.94 SQM. That fits with a noticeably bright urban sky rather than a truly dark one.
Where are the nearest dark skies to Cotonou?
The nearest really worthwhile darker site in the supplied locations is Near Comé, Mono Department, about 61 kilometres west of the city, where conditions reach Bortle 4. For an even darker Bortle 3 sky, the nearest listed options are much farther away, including Near Tchaourou, Borgou Department at 277 kilometres and Near Nkwanta South District, Oti Region at 280.6 kilometres.
Is Cotonou good for astrophotography?
It can work for the Moon, planets and brighter deep-sky targets, especially if you are comfortable working around strong skyglow. For wide-field Milky Way shots or faint nebula imaging, darker surroundings outside the city are a far better choice.
How far do you need to drive from Cotonou for darker skies?
For a clear improvement, you are looking at roughly 60 kilometres to reach a good rural sky near Comé. For genuinely dark Bortle 3 conditions, the nearest listed sites are roughly 275 to 280 kilometres away.