Twilight Times & Phases

Twilight is the time when the sky is lit by the Sun below the horizon. It is divided into three phases by how far below the horizon the Sun sits. Times for your location and date are computed in the calculator above; the definitions are timeless.

Civil twilight

The Sun is 0–6° below the horizon. The brightest objects are visible and, in clear conditions, there is enough natural light for most outdoor activity. (Sun -0.833° to -6°.)

Nautical twilight

The Sun is 6–12° below the horizon. The horizon at sea is still faintly discernible and brighter stars are usable for navigation. (Sun -6° to -12°.)

Astronomical twilight

The Sun is 12–18° below the horizon. Scattered sunlight still faintly lights the sky; beyond −18° is astronomical night, the darkest sky. (Sun -12° to -18°.)

Near the poles and in high-latitude summers, the Sun may never rise, never set, or never get dark enough for a given phase. The calculator reports these honestly and shows the affected times as unavailable rather than inventing them.

polar day

The Sun stays above the horizon for the whole 24 hours (the midnight Sun) — there is no sunrise or sunset.

polar night

The Sun stays below the horizon for the whole 24 hours — there is no sunrise or sunset.

no civil twilight

The Sun never sinks below −6°, so it never gets darker than civil twilight (a bright 'white night').

no nautical twilight

The Sun never sinks below −12°, so nautical (and astronomical) darkness does not occur.

no astronomical twilight

The Sun never sinks below −18°, so true astronomical night does not occur.