Twilight times by city

When twilight matters

Twilight is the interval when the sun is below the horizon but still brightens the sky. Civil twilight, ending at 6 degrees below the horizon, is usually the last period when outdoor work can continue without much artificial light. Nautical twilight, at 12 degrees, is dimmer: the horizon can still be visible at sea, which is why the definition remains useful for navigation and military planning. Astronomical twilight ends at 18 degrees; after that, sky glow from the sun is low enough that fainter stars and deep-sky targets become easier to see.

Photographers use these boundaries to separate setup light, blue-hour color, and dark-sky work. The clock times shift with latitude, season, longitude, and daylight saving time, so city-specific calculations are more useful than a fixed rule of thumb. The solar position math here follows Jean Meeus, Astronomical Algorithms, 2nd edition, then tests the sun crossing -6, -12, and -18 degree elevations for the selected local day.

Planning softer low-angle sunlight too? Use the golden hour calculator for sunrise, sunset, blue hour, and photography windows.

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