Twilight Types Explained — Civil, Nautical & Astronomical

The Sun sets. But the sky doesn't go dark instantly. Between sunset and true night lies twilight — a gradient of fading light that photographers chase, sailors depend on, and astronomers wait through. There are three distinct phases, and each matters for a different reason.

The Three Phases of Twilight

Civil Twilight (0° to −6°)

The Sun is just below the horizon, and there's still enough natural light to read a book or walk without a flashlight. Only the brightest planets and stars become visible.

Who cares:

• Photographers — this is the blue hour, prized for its soft, even light and deep blue sky tones. Landscape and cityscape photographers plan entire shoots around this 20–40 minute window.
• Legal systems — most jurisdictions define "sunrise" and "sunset" as the beginning and end of civil twilight for traffic laws, aviation regulations, and outdoor work rules.
• Commuters — if you drive at dusk, civil twilight is when you should already have your headlights on.

Nautical Twilight (−6° to −12°)

The horizon is still visible at sea, but artificial light is needed for most ground activities.

Who cares:

• Sailors — the name says it. During nautical twilight, a navigator can still see the horizon line while also spotting bright navigational stars. This is the window for taking celestial fixes with a marine sextant.
• Military — nautical twilight defines tactical light conditions for many armed forces. "Begin morning nautical twilight" (BMNT) and "end evening nautical twilight" (EENT) are standard operational terms.

Astronomical Twilight (−12° to −18°)

To the naked eye, the sky looks dark. But for telescope users, there's still a faint glow near the horizon that washes out the dimmest deep-sky objects.

Who cares:

• Astrophotographers & astronomers — true dark-sky observing only begins when the Sun drops below −18°. Until then, faint nebulae and galaxies remain washed out. The dark window — the time between astronomical dusk and the next dawn — is your usable imaging time.
• Night sky tourists — if you've booked a stargazing trip, astronomical twilight end is the moment the Milky Way becomes fully visible.

Beyond Twilight: True Night (below −18°)

The Sun is more than 18° below the horizon. No trace of sunlight reaches the upper atmosphere. This is astronomical night — the darkest possible sky at your location.

At high latitudes in summer, astronomical night may never arrive. Above ~48° latitude (Paris, Vancouver), the Sun doesn't drop below −18° around the June solstice. Above the Arctic Circle, even civil twilight can last all "night."

Twilight Timing by Latitude

| Location | Latitude | Summer Twilight Duration | |----------|----------|-------------------------| | Singapore | 1° N | ~1 hour 10 min | | London | 51° N | ~2 hours 30 min | | Stockholm | 59° N | All night (no true darkness) | | Tromsø | 69° N | Midnight sun — no twilight at all |

Near the equator, the Sun drops steeply — twilight is short. At high latitudes, the Sun's path is shallower, extending twilight into a prolonged, beautiful glow. This is why Scandinavian summer evenings feel endless.

How to Find Your Local Twilight Times

1. Enter a date — today, tomorrow, or any date between 1582 and 2100
2. Enter your coordinates — latitude and longitude, or use "My Location" to auto-detect
3. Read your results — civil, nautical, and astronomical twilight start and end times, plus a colour-coded 24-hour timeline showing exactly when each phase begins and ends

Try the Free Twilight Calculator →

Why This Calculator Is Private

Your location coordinates are used only in your browser to compute the Sun's position using the Jean Meeus solar algorithm. No data is ever sent to a server, stored in a database, or shared with third parties. The calculation is accurate to approximately ±1 minute for dates between 1901 and 2099.