“If you want to know how much darkness there is around you, you must sharpen your eyes, peering at the faint lights in the distance.”
― Italo Calvino, Invisible Cities
― Italo Calvino, Invisible Cities
(…)
Nautical twilight begins when there is enough illumination for sailors to distinguish the horizon at sea but the sky is too dark to perform outdoor activities (except with artificial light).
Formally, nautical twilight begins when the Sun is 12 degrees below the horizon in the morning. The sky becomes light enough to clearly distinguish it from land and water.
Nautical dawn marks the start of nautical twilight, which lasts until civil dawn.
At nautical dusk, the Sun apparently moves to 12° below the horizon in the evening. It marks the end of nautical twilight, which begins at civil dusk.
At this time, objects are less distinguishable, and stars and planets appear to brighten.
(...)
sun up, sun down. 2018.
