Civil, nautical and astronomical twilight: what each one means
Twilight is the time between day and night when the sun is already below the horizon but the sky is still lit, because the upper atmosphere keeps scattering its light. It is not a single moment: it has three stages, and each one is defined by how far the centre of the sun has sunk below the horizon.
Move the sun below the horizon
Drag the slider to see which stage of the sky each height of the sun corresponds to.
The three stages at a glance
| Stage | Centre of the sun | What you see |
|---|---|---|
| Daylight | above −0.833° | The sun, or part of it, is above the horizon. |
| Civil twilight | −0.833° to −6° | There is still enough light for most things outdoors. When it ends, you usually need artificial light. |
| Nautical twilight | −6° to −12° | On a night without moon the horizon is still visible, so sailors can measure the height of stars above it to find their position. |
| Astronomical twilight | −12° to −18° | The sky looks dark, but a faint glow of sunlight remains. Below −18°, that light is fainter than the light of the stars. |
| Night | below −18° | No sunlight is left in the sky. |
When exactly is sunrise?
Sunrise and sunset are the moments when the top edge of the sun touches the horizon. The atmosphere bends light by about 34′ at the horizon and the sun has a radius of about 16′, so that happens when its centre is 50′ (0.833°) below the horizon. That is the definition used by the US Naval Observatory, and the one arcofday uses for every city.
Golden hour and blue hour
Neither has an official definition. Photographers usually call golden hour the time when the sun is between 6° above and 4° below the horizon, and blue hour the time between 4° and 6° below, the darkest part of civil twilight. arcofday uses that convention, the one popularised by PhotoPills.
Why twilight lasts longer far from the equator
Near the equator the sun sets almost vertically, and civil twilight is over about 20 minutes after sunset. At higher latitudes it sets at a slant and twilight lasts much longer. These are the durations of civil twilight (from sunset until it ends) calculated for some of our cities:
| City | Latitude | 23 September | 21 June |
|---|---|---|---|
| Quito | 0.2° S | 20 min | 23 min |
| Singapore | 1.3° N | 21 min | 23 min |
| Madrid | 40.4° N | 28 min | 33 min |
| Paris | 48.9° N | 31 min | 43 min |
| Dublin | 53.3° N | 35 min | 52 min |
| Stockholm | 59.3° N | 40 min | 92 min |
| Oslo | 59.9° N | 41 min | 104 min |
Around the June solstice the sun never gets 18° below the horizon north of about 48.6° N, so there is no full night: in Paris astronomical twilight joins dusk to dawn. North of about 54.6° N nautical twilight does not end either, as in Oslo, and north of about 60.6° N even civil twilight lasts all night.
Why the earliest sunset is not on the shortest day
The shortest day of 2026 in Madrid is 21 December, but the earliest sunset comes on 7 December (17:48) and the latest sunrise on 4 January (08:38). The reason is the equation of time: over the year, solar noon drifts a few minutes earlier or later against the clock, and around the December solstice it moves later every day. Madrid →
Twilight times for your city
Every city page shows today’s dawn and dusk for each stage, the golden and blue hours and the whole year. See all cities →