Twilight is the time after the Sun sets when it is still light. The Sun is below the horizon but it’s rays continue to light up the sky. Twilight continues until the Sun sinks 18º below the horizon. There are three phases of twilight:
- Civil (Sun is up to 6º below horizon)
- Nautical (7º to 12º below)
- Astronomical (13º to 18º below)
