Dusk - Technical Definitions

Technical Definitions

There are also more technical definitions of dusk, including the following:

Civil dusk
The time at which the sun is 6 degrees below the horizon in the evening. At this time objects are distinguishable and some stars and planets are visible to the naked eye.
Nautical dusk
Is when the sun is 12 degrees below the horizon in the evening. At this time, objects are no longer distinguishable, and the horizon is no longer visible to the naked eye.
Astronomical dusk
The time at which the sun is 18 degrees below the horizon in the evening. At this time the sun no longer illuminates the sky, and thus no longer interferes with astronomical observations.


  • Dusk in Porto Covo, west coast of Portugal

  • Dusk, seen from a plane on cruise

  • São Paulo at dusk, view from Ibirapuera Park

  • Dusk in Joshua Tree, California, USA

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