Nautical twilight
Astronomy Nautical dawn Nautical dusk
During nautical twilight, the sun’s centre lies between 6° and 12° below the horizon. Many stars are visible while, in good conditions, the horizon can still be distinguished.
Why sailors gave it its name
Navigation by stars required two things at once: recognisable stars and a visible horizon. Under favourable conditions, nautical twilight provides that combination, which explains the name.
Where it fits into the evening
- Civil twilight comes first, ending at 6° below the horizon.
- Nautical twilight follows, from 6° to 12°.
- Astronomical twilight comes next. The order reverses in the morning.
Dark enough for what?
Bright stars and planets can already be observed. Faint galaxies and nebulae still lose contrast against the remaining scattered sunlight. Moonlight, haze and artificial lighting can brighten the sky further.
Do not plan from the clock alone
Duration depends on location and season. This phase can stretch through northern Germany’s long summer twilight. An open horizon helps observation, but the calculated boundary is unchanged by a building blocking the view. A street lamp is not an astronomical measuring instrument either.