The night sky is the nighttime appearance of celestial objects like stars, planets, and the Moon, which are visible in a clear sky between sunset and sunrise, when the Sun is below the horizon.
Stars in the night sky
The Milky Way is brighter in the Southern Hemisphere than in the North. (Photo taken at La Silla Observatory)
Paranal Observatory nights. The concept of noctcaelador tackles the aesthetic perception of the night sky.
The Milky Way contains billions of stars, arranged in two strikingly different structures: halo and disc.
Night or nighttime is the period of darkness when the Sun is below the horizon. The opposite of nighttime is daytime. Sunlight illuminates one side of the Earth, leaving the other in darkness. Earth's rotation causes the appearance of sunrise and sunset. Moonlight, airglow, starlight, and light pollution dimly illuminate night. The duration of day, night, and twilight varies depending on the time of year and the latitude. Night on other celestial bodies is affected by their rotation and orbital periods. The planets Mercury and Venus have much longer nights than Earth. On Venus, night lasts 120 Earth days. The Moon's rotation is tidally locked, rotating so that the near side of the Moon always faces Earth. Nightfall across the near the side of the Moon results in the lunar phases visible from Earth.
Night sky over a bog in Estonia, with light pollution visible on the horizon
The drainage basin of the Nile river and delta at night
Sunset on Mars
Nocturnal insects drawn to an artificial light