Sunset

Sunset is the daily disappearance of the Sun below the horizon as seen from an observer on Earth, marking the transition from day to evening. It results from the rotation of the Earth on its axis and the observer’s changing perspective as the planet turns away from the Sun. The exact moment of sunset depends on latitude, season, longitude, altitude, and local topography. In practice, people often reference the period around sunset rather than the precise instant.

During sunset, sunlight travels through a longer path in the atmosphere, which scatters shorter wavelengths and leaves longer wavelengths to reach the observer, producing reddish and orange hues. Atmospheric refraction also lifts the Sun slightly above its geometric position, so the solar disk may appear above the horizon even after its geometric setting.

Conditions such as atmospheric particles, humidity, and pollution intensify colors. The phenomenon known as the green flash can occur briefly at sunset under favorable conditions.

Sunset has cultural and practical significance. It commonly marks the end of the workday in many regions, influences daily routines, and is a frequent subject in art and literature. In maritime contexts, sunset and twilight periods have historically aided navigation and timekeeping. The period after sunset, known as twilight, varies in length depending on latitude and season.