The time when the Sun is below the horizon is known as night or midnight. Daytime is the antithesis of midnight. One half of the Earth is illuminated by sunlight, while the other is left in darkness. Sunrise and sunset emerge as a result of Earth's rotation. The night is poorly illuminated by light pollution, stars, moonlight, and airglow. The length of day, night, and twilight vary according on the latitude and season. Other celestial bodies' rotation and orbital periods have an impact on night. The evenings on Mercury and Venus are far longer than those on Earth. Night lasts 120 Earth days on Venus. One of the moon's sides is constantly facing Earth due to the moon's tidally locked rotation. Darkness on some areas of the near side of the Moon causes lunar phases that may be seen from Earth.

Darkness:

In the spectrum of visual perception known as scotopic vision, human eyesight cannot identify colors in extremely low brightness because the retina's hue-sensitive photoreceptor cells become dormant when light levels are inadequate. Many civilizations have developed metaphorical uses of the phrase to refer to an unpleasant or ominous sensation as a result of the emotional reaction to darkness. Nightfall can also be referred to as "darkness" as it happens when the Sun is more than 18° below the horizon.

The changes that come with nightfall—darkness, higher humidity, and colder temperatures—have an impact on organisms. They respond by directly reacting to and modifying circadian rhythms, which are controlled by an internal biological clock. An organism's behavior and physiology are impacted by these circadian rhythms, which are controlled by exposure to light and darkness. Nocturnal animals are those that are more active at night and have adapted to low light levels by developing various night vision techniques and intensifying their other senses. Animals that are diurnal—mammals, birds, and certain others—are active during the day and sleep at night. When darkness falls, fungi promptly react by increasing their biomass.

Night has always been a more dangerous and insecure time of day. After sundown, many of the social restrictions of the daytime vanished. Reduced visibility contributed to an increase in theft, fighting, murders, forbidden sexual practices, and incidents of unintentional death. Deities connected to any or all of these evening characteristics have been used by cultures to personify night. Many cultures include "creatures of the night," such as werewolves, witches, ghosts, and goblins, in their mythology, which represent society worries and concerns. Daytime activities were expanded with the advent of artificial lights. throughout the 1600s, lanterns with oil lamps and candles were suspended throughout major European cities. Unprecedented lighting was produced by gas and electric lights in the nineteenth century. Numerous enterprises implemented a night shift, and the variety of recreational pursuits that were deemed socially acceptable increased. Nightlife, which includes nightclubs, bars, and cultural establishments,