Civil, nautical and astronomical twilight: how long they last

nightlightThe three stages

What each stage of twilight looks like

Each stage of twilight is defined by the sun’s depth below the horizon, not by the clock, so the same stage looks the same everywhere.

• Civil twilight, from sunset until the sun is 6° down: there is enough light to work outdoors without lamps, the brightest planets appear, and street lights switch on. It is the twilight rules usually mean; in US aviation rules, for example, night begins when evening civil twilight ends.
• Nautical twilight, from 6° to 12°: the sea horizon is still visible, so navigators could measure the height of the brightest stars against it. On land the outlines of hills and buildings remain against the sky.
• Astronomical twilight, from 12° to 18°: most people would call it night, but a faint glow persists low in the west, enough to wash out the faintest galaxies. Below 18° the sky is as dark as the sun can leave it.

The photographers’ blue hour sits inside civil twilight, while the sun is between 4° and 6° below the horizon. In the morning everything runs in reverse: astronomical dawn first, then nautical dawn, civil dawn and sunrise.

show_chartThe numbers

How long each stage lasts

Near the equator each stage takes less than half an hour and the whole of twilight is over in about 70 minutes. At mid-latitudes it stretches, most of all in summer. On the March equinox in London the sun sets at 18:13, civil twilight ends at 18:46, nautical at 19:26 and astronomical at 20:07; in New York the same steps come at 19:08, 19:35, 20:07 and 20:40.

functionsThe geometry

Why twilight is short in the tropics and long in the north

The sun always turns around the celestial pole at 15° an hour; what changes is the angle at which its path crosses the horizon. On the equator it sets vertically, so it sinks 18° in about 72 minutes. At 52° north its path at the equinox meets the horizon at 38°, and the same 18° take nearly two hours. In summer the path near midnight runs almost along the horizon at high latitudes, and the sun lingers in twilight for hours, the same effect that makes the golden hour longer there.

dark_modeLight all night

Where the night never gets fully dark

At midsummer midnight the sun sinks only as far below the northern horizon as 90° minus your latitude minus 23.4°. North of about 48.7°, which takes in Paris, London, Berlin and Warsaw, it never reaches 18° around the June solstice, so astronomical twilight runs straight through the night. In London that lasts 60 nights in 2026, from 22 May to 20 July.

• From about 54.7° north, Copenhagen, Moscow or Edinburgh, the sun never gets 12° down around midsummer: nautical twilight all night. In Oslo it lasts 81 nights, from 12 May to 31 July.
• From about 60.7° north the sun stays within 6° of the horizon: civil twilight all night, the white nights. Further north still the sun does not set at all; see midnight sun and polar night.

In the southern hemisphere the same happens in December, but very few people live far enough south to see it.

photo_cameraUsing it

Planning around twilight

• Photography: the blue hour and the glow after sunset fall in civil twilight; city lights and the sky balance best in its second half.
• Stargazing: for the Milky Way or faint objects wait until astronomical twilight ends, and check the moon. In June at mid-northern latitudes that moment never comes.
• Outdoor plans: civil twilight adds a useful half hour or more of light after sunset for a walk or a ride home.

The sunrise and sunset calculator lists every stage of dawn and dusk for any place and date, and the map shades them on its timeline.

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