What is the difference between civil, nautical and astronomical twilight?
They are three steps of Sun angle after sunset: civil twilight ends when the Sun's centre is 6° below the horizon, nautical at 12° and astronomical at 18°. Each step is darker, and each changes what you can see and shoot (National Weather Service).
Tonight's twilight times, estimated
Calculated in your browser with the NOAA solar algorithm for a flat horizon. Treat every time as an estimate to within a minute or two.
| Phase | Sun angle | Starts | Ends | Length |
|---|
Same three angles everywhere; very different clocks depending on latitude and season.
The evening glossary, in order
Twelve terms from the first warm light to full night. The one lit up matches the scrubber above.
about +6° to −4°
Golden hour
The low-Sun window when light is warm and shadows are long. It is a photographers' convention, not an official term, so apps draw the edges differently. We use the Sun from about 6° above to 4° below the horizon.
degrees above or below
Sun altitude
The Sun's angle above (+) or below (−) the horizon. Every term on this page is really just an altitude range, which is why times shift with season and latitude.
compass direction
Azimuth (bearing)
Where on the horizon the Sun sits, in degrees from north: 270° is due west. Asterfold shows it as a bearing, like 258° WSW, so you can aim a viewpoint.
centre at −0.833°
Sunset
The moment the top edge of the Sun drops below a flat horizon. Calculators time it for the Sun's centre a little below the horizon; NOAA's solar calculator uses a 0.833° allowance for atmospheric refraction (NOAA GML).
light bending
Refraction
The atmosphere bends sunlight near the horizon, so the Sun looks higher than it is. NOAA notes the effect varies with pressure, humidity and temperature (NOAA GML), one reason real sunsets can differ from tables by a minute or two.
0° to −6°
Civil twilight
From sunset until the Sun's centre is 6° below the horizon. The brightest stars and planets appear, and the horizon and objects on the ground are still easy to see (National Weather Service).
opposite the sunset
Belt of Venus
During civil twilight, look away from the sunset: a pinkish band sits above the darker blue shadow of the Earth rising on the opposite horizon.
about −4° to −8°
Blue hour
The deep-blue window after golden hour, straddling the end of civil twilight. Like golden hour, it is a convention; its edges vary between apps and books.
−6° to −12°
Nautical twilight
The horizon is still visible at sea, so sailors could take star sights. Outlines of land are visible, but detailed outdoor work needs a light (National Weather Service).
−12° to −18°
Astronomical twilight
Most people would call it fully dark, especially near city lights. The horizon is gone, and moderately faint stars show to the naked eye under a dark sky (National Weather Service).
the end of a twilight
Dusk
Each twilight has its own dusk: civil dusk at −6°, nautical dusk at −12°, astronomical dusk at −18°. In everyday speech, “dusk” usually means the first one.
below −18°
Night
The Sun no longer lights the sky at all. Faint galaxies and the Milky Way need this, plus distance from city light. In summer at high latitudes, it may not happen at all.
Twilight questions
What is the difference between civil, nautical and astronomical twilight?
They are three bands of Sun angle below the horizon: civil twilight to 6°, nautical to 12° and astronomical to 18° (National Weather Service). Each step is darker: civil still lets you see the landscape, nautical keeps only the horizon, astronomical looks fully dark to most people.
How long does civil twilight last?
It depends on where you are and the date. Near the equator it is quick; at higher latitudes, and near the summer solstice, it lasts much longer. The calculator on this page estimates it for your city and date.
Is blue hour the same as civil twilight?
No. Blue hour is a photographers' convention, usually around 4° to 8° below the horizon, so it starts inside civil twilight and ends in nautical twilight.
When is it dark enough to see stars?
The brightest stars and planets appear during civil twilight. Many more show during nautical twilight. For faint objects like the Milky Way you need the Sun below 18°, plus a dark site.
Why do different apps give different golden hour times?
Because golden hour has no official definition. Apps pick different Sun angles for its edges. Sunset and the three twilights are standard; golden and blue hour are conventions.
Does twilight happen the same in the morning?
Yes, in reverse: astronomical, nautical, then civil twilight, then sunrise. The same Sun angles apply.
Civil vs nautical vs astronomical twilight
0° to −6°
Civil
You see: the landscape, the brightest stars and planets, the Belt of Venus.
Shoot: afterglow, silhouettes, city lights balanced with sky.
−6° to −12°
Nautical
You see: a horizon line and outlines; you need a torch to read a map.
Shoot: the end of blue hour, star trails starting, long exposures.
−12° to −18°
Astronomical
You see: what looks like night, with a faint glow in the west.
Shoot: stars, while you wait for true dark for the Milky Way.
A mini story: the pier, one evening in October
Golden hour starts at 5:26 pm in London on October 13. The photographer arrives at the pier with the shot planned in Asterfold: bearing 249°, the Sun 9° left of centre in a 60° frame. Sunset at 6:11. She stays through civil twilight for the pink band behind her, packs the long lens at nautical dusk, and logs the evening in the field journal before the car warms up: “nice,” mid cloud, would come back.
Times and angles from the app's own store screenshots for that date and spot.
Honest limits
- Every time here assumes a flat horizon. Hills, buildings and trees can hide the Sun minutes early. Asterfold has the same limit and says so.
- NOAA describes its sunrise and sunset results as accurate to within about a minute between 72° north and south, and within about ten minutes outside that range (NOAA GML).
- Golden and blue hour edges are our convention; other apps may differ by several minutes.
- Asterfold is free for the Studio, aiming, two viewpoints, the journal and tonight's ratings. Asterfold Plus adds unlimited viewpoints, smart sky alerts, the 10-day outlook and a year of sky events.
A decision we made: Asterfold labels calculated, forecast, estimated and observed data differently, so a twilight time and a cloud forecast never look equally certain.
Know the phase before you leave.
Asterfold draws the Sun's real path for any place and date, coloured by golden hour, blue hour and twilight.
Make it a habit with Asterfold
Updated November 2026
Related
- Asterfold: golden hour and sunset plannerSee where the Sun sets from your own viewpoint, when golden and blue hour start, and how the sky really turned out. Free on iPhone.
- How long does blue hour last? Myths vs factsBlue hour lasts about 15 to 40 minutes in most places, not an hour. Six myths vs facts, plus a slider that estimates it for your city and date.
- A 14-evening sunset photography challenge with dated timesA 14-evening sunset photography challenge: one prompt a night, a progress ring, and estimated sunset times and directions for your city.
- What time to book a golden hour photo sessionPick a city and date to get an estimated start time for golden hour photos: when to arrive, first frame, sunset and blue-hour wrap.