Light
Golden Hour, Blue Hour and the Three Twilights: A Photographer's Guide to the Light After Sunset
Golden hour and blue hour get most of the attention, but they're only two of the stages the sky goes through after sunset. Between the Sun touching the horizon and the Milky Way showing there are several more, and each has its own colour, its own length and its own subjects. All of them are defined by one number, which is how far the Sun is below the horizon. Once you know the stages, you know when the east turns pink, when the city lights match the sky, and how many minutes you have before each one ends.
At a glance
- The bands: golden hour is the Sun from +6° to −4°, civil twilight 0° to −6°, nautical −6° to −12°, astronomical −12° to −18°, and night is below −18°. Blue hour is around −4° to −6°.
- How long: at an equinox each twilight lasts about 20–25 minutes at the equator, 30–35 at 45° and 40–55 at 60°. In June, north of 48.6°, astronomical twilight never ends.
- Where to look: west for colour and the green flash, east for Earth's shadow and the Belt of Venus.
- Settings: ISO 100 and f/8 in golden hour. 1–30 s at ISO 100–400 in blue hour. f/2.8 and ISO 400–1600 through nautical twilight. f/1.4–f/2.8, 10–25 s and ISO 1600–6400 at night.
- The crossover: artificial lights and the sky need the same exposure 20–30 minutes after sunset at mid-latitudes, with the Sun 4–6° down.
Golden hour, blue hour and the three twilights, by Sun altitude
The three twilights have formal definitions, the ones observatories and almanacs use. Golden hour and blue hour are photographers' terms with no official limits, so sources differ by a degree or two. The values here are the ones commonly used for planning, and the table notes the variants.
| Phase | Sun altitude | What it looks like |
|---|---|---|
| Golden hour | +6° to −4° (some use +6° to −6°, or +6° to 0°) | Low, warm, directional sunlight, then orange afterglow in the west. |
| Civil twilight | 0° to −6° | Bright enough to work without lights. Venus, Jupiter and the Moon appear. |
| Blue hour | ≈ −4° to −6° (some extend it to −8°) | Deep saturated blue. Artificial lights are about as bright as the sky. |
| Nautical twilight | −6° to −12° | Bright stars out, horizon still a visible line. |
| Astronomical twilight | −12° to −18° | Dark to the eye, but the sky still glows faintly, mostly in the west. |
| Night | below −18° | No sunlight reaches the sky. It is as dark as it gets. |
The US Naval Observatory defines each boundary by what you can still do. At civil dusk you need artificial light for ordinary outdoor work. Through nautical twilight the horizon stays visible on a moonless night, so a sailor can still take star sights. Below −18° scattered sunlight is fainter than starlight. Note that sunset itself is defined with the Sun's centre 0.833° below the horizon (16′ of solar radius plus 34′ of refraction), so civil twilight measured from sunset is a little shorter than a full 6° would suggest.
The Sun & Moon card in Still Dark lists sunset, the end of civil, nautical and astronomical twilight, and the golden and blue hour windows for your location on any date, along with the Sun's azimuth at sunset. From that you get the direction of the afterglow and of the anti-solar point opposite it.
Why golden hour is orange and blue hour is blue
Air molecules are far smaller than the wavelength of light, so they scatter it in the Rayleigh regime, where scattered intensity goes as the inverse fourth power of wavelength (λ⁻⁴). Blue at 450 nm is scattered about four times more than red at 650 nm, and violet at 400 nm about nine times more than deep red at 700 nm. That scattered blue is what you see when you look at the daytime sky away from the Sun.
At sunset the same scattering has the opposite result. Light from a Sun on the horizon has crossed dozens of times more air than at noon, and most of the blue has been scattered out along the way. What's left is orange and red. That reddened light also falls on clouds and haze, which is why the west keeps glowing after the Sun has gone, and why dust, smoke and volcanic aerosols make the reds deeper.
The blue of the blue hour has a different cause. With the Sun below the horizon, the light reaching the sky overhead has taken a long path through the upper atmosphere, where ozone absorbs across the yellow, orange and red (the Chappuis bands). What's left is a deep, saturated blue without the whiteness of the daytime sky.
Things worth turning around for
- Earth's shadow and the Belt of Venus. Turn away from the sunset a few minutes after it. A blue-grey band rises from the eastern horizon. That's Earth's own shadow on the atmosphere. Above it is a pink band, the Belt of Venus, which is sunlight reddened by its long path and scattered back toward you. The shadow rises as fast as the Sun sinks. The belt sits about 10–20° up and fades about 20 minutes after sunset as the boundary blurs. It's best over a low, flat horizon. Most people miss it because they're still looking at the sunset.
- Alpenglow. Strictly, this is the pink glow on peaks after the Sun has set where you are, lit by the same backscattered light as the Belt of Venus. People also use the word for any low-Sun light on a mountain. The strict kind is fainter and lasts a few minutes.
- Crepuscular and anticrepuscular rays. Beams and shadows through gaps in clouds near the Sun. The rays are parallel and only look like they fan out because of perspective, like railway tracks. Turn around and they converge again at the anti-solar point, where they're fainter and easy to miss.
- The green flash. Refraction is stronger for shorter wavelengths, so the Sun's upper edge has a green fringe for a moment as the last of the disc goes. A mirage layer over the sea can make it bigger. It lasts a second or two at most and needs a very clear, distant horizon. Watch only the last sliver, with a long lens on burst.
How long does twilight last?
It depends on how steeply the Sun's path meets the horizon. At the equator at an equinox the Sun drops straight down at 15° per hour, so each 6° band takes 24 minutes. At higher latitudes it moves along the horizon at a shallow angle and the same 6° takes longer. The season changes the angle too, but latitude matters more.
| Latitude (equinox) | Civil (sunset → −6°) | Nautical (−6° → −12°) | Astronomical (−12° → −18°) | Sunset to night |
|---|---|---|---|---|
| 0° | ≈ 21 min | ≈ 24 min | ≈ 24 min | ≈ 1 h 09 |
| 30° | ≈ 24 min | ≈ 28 min | ≈ 28 min | ≈ 1 h 20 |
| 45° | ≈ 29 min | ≈ 34 min | ≈ 35 min | ≈ 1 h 39 |
| 60° | ≈ 42 min | ≈ 50 min | ≈ 55 min | ≈ 2 h 26 |
These are approximate. They're computed for the Sun at 0° declination with sunset at −0.83°, and they match timeanddate's tables for Quito (0°) and Helsinki (60°) on 22 September 2026 to within a minute.
White nights. At the June solstice the Sun's declination is +23.4°, so at midnight it sits (90° − latitude − 23.4°) below the horizon. For that to reach −18° the latitude has to be below 90° − 23.4° − 18° = 48.6° (48°34′). North of that line, which includes Paris, Vancouver, Prague and all of the British Isles, astronomical twilight runs from dusk into dawn for weeks around the solstice. Above 54.6° nautical twilight lasts all night, and from 60.6° to the polar circle the sky never leaves civil twilight. These are the white nights of St Petersburg and Helsinki. You notice it even at 40° N. Philadelphia on 21 June 2026 gets under five hours of full darkness, from 10:36 pm to 3:28 am.
What to photograph in each phase
- Golden hour: landscapes in warm side-light with long shadows, backlit subjects, the Sun on the horizon with a long lens, and the green flash on its last sliver.
- Civil twilight: the Belt of Venus in the east, alpenglow, and a thin crescent Moon and Venus appearing in the west. They look best against a sky that's still bright, with some foreground in the frame. Jupiter follows minutes later.
- Blue hour: cityscapes, bridges, lit buildings, headlight trails, and any landscape with a warm light in it. The camera records the blue more strongly than you see it.
- Nautical twilight: ISS and satellite passes. The station has to be in sunlight while your sky is dark, and that happens in this window and the hour after it. Also first-magnitude stars over a still-visible horizon, and a crescent Moon with earthshine.
- Astronomical twilight: the last glow in the west makes a gradient behind wide star fields. Start star-trail sequences now so the first frames have some colour.
- Night: the Milky Way and deep-sky work. The galactic core needs the Sun below −18° and no Moon. Otherwise the sky background is too bright for it.
Golden hour and blue hour camera settings
| Phase | Aperture | Shutter | ISO | White balance |
|---|---|---|---|---|
| Golden hour | f/8–f/11 | 1/60–1/500 s | 100–200 | 5200–6000 K |
| Blue hour | f/5.6–f/11 | 1–30 s, tripod | 100–400 | 3200–4500 K to keep city lights neutral, 5500 K for a purer blue |
| Nautical twilight | f/2.8–f/5.6 | 5–30 s | 400–1600 | 3800–4500 K |
| Astronomical twilight and night | f/1.4–f/2.8 | 10–25 s (NPF or 500 rule) | 1600–6400 | 3800–4200 K |
Shoot RAW and set the white balance manually for any sequence, or the colour will drift from frame to frame as the light changes. The light drops by roughly a stop every few minutes through civil twilight, so keep re-metering. A setting from ten minutes ago will be wrong. Once the sky needs f/2.8 and ISO 1600, focus manually on a star at full magnification.
The blue hour exposure crossover
There's a short time each evening when the sky and the artificial lights in the scene need the same exposure. Before it, the lights are small points in a bright scene. After it, they blow out and the sky goes black. At mid-latitudes it comes about 20–30 minutes after sunset, with the Sun 4–6° down, and lasts roughly ten minutes. Set up before sunset and take a frame every two or three minutes from the moment the Sun goes. One of those frames will be the balanced one. You can't pick the moment by eye, because your eye adapts and the sensor doesn't. Near the equator the window comes sooner and ends sooner (blue hour in Quito lasts about 16 minutes). At 60° it lasts half an hour or more.
Planning a golden hour or blue hour shoot
Face the anti-solar point for the Belt of Venus. The pink band is centred exactly opposite the Sun, so if the Sun set at azimuth 300°, look toward 120°. Earth's shadow is highest and sharpest there.
The sunset direction moves through the year. The Sun sets due west only at the equinoxes. At 40° N it sets at about 302° (west-northwest) at the June solstice and about 240° (west-southwest) at the December solstice, a swing of over 60°. The swing is about 47° at the equator and over 100° at 60° N. A valley aligned with the June sunset is 60° off in December, and the anti-solar point moves by the same amount the other way.
The Moon changes what comes after twilight. Around full Moon it rises at sunset and the blue hour runs straight into moonlight. Landscapes stay lit and you can't see the Milky Way. Around first quarter it's high at dusk and sets near midnight, so darkness comes late. From last quarter to a few days past new, the evening gets fully dark at the usual time, so those are the two weeks for the Milky Way. The Moon makes no difference to the blue-hour crossover, so use the full-Moon week for that and for moonlit landscapes.
The Planner draws the Sun's direction line on the map for any date and time, so you can see the sunset azimuth, and the point directly opposite it where Earth's shadow and the Belt of Venus rise, against the real terrain. Drag the time through the evening to watch the line move, and use the altitude curves on the timeline to see when the Sun crosses −6°, −12° and −18° and where the Moon is when it does.
Common mistakes
- Packing up at sunset. The Belt of Venus, alpenglow and the blue hour all happen after the Sun has gone. People leave the car park just as these start.
- Facing the wrong way. The pink band and the shadow are in the east at dusk, not in the sunset.
- Auto white balance through a sequence. Every frame comes out a different colour.
- Expecting the Milky Way in June from northern Europe. North of 48.6° the sky never reaches astronomical night around the solstice.
- Ignoring the Moon. A full Moon rising at sunset turns the blue hour into a moonlit night.
- Judging the crossover by eye. Bracket in time and choose the balanced frame later.
FAQ
How long after sunset is blue hour?
It starts with the Sun about 4° below the horizon, roughly 15–20 minutes after sunset at mid-latitudes, and runs to about −6°, about 25–35 minutes after sunset. Sources that extend it to −8° add ten minutes or so. It's shorter near the equator and longer at high latitudes.
What's the difference between civil, nautical and astronomical twilight?
They're bands of Sun altitude: civil from sunset to −6°, nautical −6° to −12°, astronomical −12° to −18°. In civil twilight it's light enough to work outdoors. In nautical the horizon is still visible. Astronomical looks dark, but the sky still glows faintly. Below −18° it's night.
Why does the sky in the east turn pink after sunset?
That's the Belt of Venus, which is reddened sunlight scattered back from the atmosphere opposite the Sun. The blue-grey band beneath it is Earth's own shadow rising as the Sun sinks. It shows for about 20 minutes after sunset on any clear evening.
Why doesn't it get properly dark in summer?
Around the June solstice the Sun never gets 18° below the horizon north of about 48.6°, so astronomical twilight lasts all night. Above 54.6° nautical twilight lasts all night, and above 60.6° civil twilight does. Those are the white nights. Wait for August, or travel south.
Which direction does the Sun set?
Due west only at the equinoxes. At 40° N it sets around 302° in late June and around 240° in late December. The range narrows toward the equator and widens toward the poles. The Sun & Moon card gives the exact azimuth for your date and place.
Sources and further reading
- US Naval Observatory — Rise, Set, and Twilight Definitions (the −6°/−12°/−18° definitions and sunset at −0.833°).
- timeanddate — The Golden Hour and The Blue Hour (their +6°/−6° and −4°/−8° conventions, durations by latitude, the ozone explanation of the blue).
- Wikipedia — Twilight (48°34′, 54°34′ and 60°34′ all-night thresholds) and Rayleigh scattering (the λ⁻⁴ law).
- NASA Space Place — Why Is the Sky Blue? (short wavelengths scattered, the longer sunset path).
- EarthSky — Watch for Earth's shadow and the Belt of Venus and Crepuscular rays; Sky at Night — How to see the Belt of Venus (10–20° altitude, up to 20 minutes).
- Atmospheric Optics — The Antisolar Point; Wikipedia — Green flash (duration and conditions).