When is the sky considered fully dark, or night, setting in based on the sun's position?
Answer
When the sun passes 18 degrees below the horizon.
The sky is deemed fully dark, transitioning to night, once the sun's center has moved beyond 18 degrees below the true horizon, as residual sunlight becomes too faint to interfere with observations.
Related Questions
What is the broad, casual term used to describe the illumination remaining in the sky after the sun sets?Until what angular distance below the horizon does Civil Twilight last?What primary limitation characterizes the visibility during Nautical Twilight?When is the sky considered fully dark, or night, setting in based on the sun's position?Which color wavelengths are filtered out by atmospheric scattering as the sun sets, allowing warmer colors to dominate near the horizon?Where is the phenomenon known as Alpenglow typically observed?What causes the predominant blue hue observed during the Blue Hour?What key activity can still be conducted without artificial illumination during Civil Twilight?How does the duration of twilight stages generally change when moving from the equator toward higher latitudes?Why might the evening afterglow potentially show deeper red hues compared to the pre-dawn glow?What is the angular range of the sun's center below the horizon during Nautical Twilight?