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Night or nighttime is the period of time when the sun is below the horizon. The opposite of night is day (or "daytime" to distinguish it from "day" as used for a 24-hour period). Time of day varies based on factors such as season, latitude, longitude and timezone. Look up night in Wiktionary, the free dictionary. ... Wikipedia does not have an article with this exact name. ... Wiktionary (a portmanteau of wiki and dictionary) is a multilingual, Web-based project to create a free content dictionary, available in over 151 languages. ... This article is about the concept of time. ... Sol redirects here. ... Horizon. ... Look up day in Wiktionary, the free dictionary. ... Look up daylight in Wiktionary, the free dictionary. ... This article or section is in need of attention from an expert on the subject. ... This article is about the geographical term. ... Longitude is the east-west geographic coordinate measurement most commonly utilized in cartography and global navigation. ... TimeZone is an Internet forum for discussion of watches and horology. ...

Duration and geography

A composite image showing the terminator dividing night from day, running across Europe and Africa. Observers on the surface of the earth along this terminator will see a sunset.

Nights are shorter than days on average due to two factors. One, the sun is not a point, but has an apparent size of about 32 minutes of arc. Two, the atmosphere refracts sunlight so that some of it reaches the ground when the sun is below the horizon by about 34 minutes of arc. The combinaton of these two factors means that light reaches the ground when the centre of the sun is below the horizon by about 50 minutes of arc. Without these effects, day and night would be the same length at the autumnal (autumn/fall) and vernal (spring) equinoxes, the moments when the sun passes over the equator. In reality, around the equinoxes the day is almost 14 minutes longer than the night at the equator, and even more closer to the poles. The summer and winter solstices mark the shortest night and the longest night, respectively. Download high resolution version (1024x1024, 143 KB) Wikipedia does not have an article with this exact name. ... Download high resolution version (1024x1024, 143 KB) Wikipedia does not have an article with this exact name. ... World map with terminator (April) A composite image showing the terminator dividing night from day, running across Europe and Africa. ... A composite image showing the terminator dividing night from day, running across Europe and Africa. ... Illumination of Earth by Sun on the day of equinox The autumnal equinox (or fall equinox) marks the beginning of astronomical autumn. ... Illumination of Earth by Sun on the day of equinox The vernal equinox (or spring equinox) marks the beginning of astronomical spring. ... For other uses, see Equinox (disambiguation). ... World map showing the equator in red For other uses, see Equator (disambiguation). ... For other uses, see Summer (disambiguation). ... For other uses, see Winter (disambiguation). ... “Summer solstice” redirects here. ... This article is about the astronomical and cultural event of winters solstice, also known as midwinter. ...

The closer a location is to the North or South Pole, the larger the range of variation in the night's length. Although equinoxes occur with a day and night close to equal length, before and after an equinox the ratio of night to day changes more rapidly in locations near the poles than in locations between the Tropic of Cancer and the Tropic of Capricorn. In the Northern Hemisphere, Denmark has shorter nights in June than India has. In the Southern Hemisphere, Antarctica has longer nights in June than Chile has. The Northern and Southern Hemispheres of the world experience the same patterns of night length at the same latitudes, but the cycles are 6 months apart so that one hemisphere experiences long nights (winter) while the other is experiencing short nights (summer). For other uses, see North Pole (disambiguation). ... For other uses, see South Pole (disambiguation). ... For the novel by Henry Miller, see Tropic of Cancer (novel). ... World map showing the Tropic of Capricorn For the novel by Henry Miller, see Tropic of Capricorn (novel). ... Northern hemisphere highlighted in yellow. ... southern hemisphere highlighted in yellow (Antarctica not depicted). ... This article is about the geographical term. ...

Between the pole and the polar circle, the variation in daylight hours is so extreme that for a portion of the summer, there is no longer an intervening night between consecutive days and in the winter there is a period that there is no intervening day between consecutive nights.

On other celestial bodies

The phenomenon of day and night is due to the rotation of a celestial body about its axis, creating the illusion of the sun rising and setting. Different bodies spin at very different rates, however. Some may spin much faster than Earth, while others spin extremely slowly, leading to very long days and nights. The planet Venus rotates once every 243 days – by far the slowest rotation period of any of the major planets. In contrast, the gas giant Jupiter's sidereal day is only 9 hours and 56 minutes.^[1] A planet may experience large temperature variations between day and night, such as Mercury, the closest planet to the sun. This is one consideration in terms of planetary habitability or the possibility of extraterrestrial life. See lists of astronomical objects for a list of the various lists of astronomical objects in Wikipedia. ... This article is about Earth as a planet. ... For other uses, see Venus (disambiguation). ... For other uses, see Jupiter (disambiguation). ... On a prograde planet like the Earth, the sidereal day is shorter than the solar day. ... This article is about the planet. ... Understanding planetary habitability is partly an extrapolation of the Earths conditions, as it is the only planet currently known to support life. ... Green people redirects here. ...

Impact on life

Bats are just one of the thousands of species of animals that are active during the night

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The disappearance of sunlight, the primary energy source for life on Earth, has dramatic impacts on the morphology, physiology and behavior of almost every organism. Some animals sleep during the night, while other nocturnal animals including moths and crickets are active during this time. The effects of day and night are not seen in the animal kingdom alone, plants have also evolved adaptations to cope best with the lack of sunlight during this time. For example, crassulacean acid metabolism in a unique type of carbon fixation which allows photosynthetic plants to store carbon dioxide in their tissues as organic acids during the night, which can then be used during the day to synthesize carbohydrates. This allows them to keep their stomata closed during the daytime, preventing transpiration of precious water. Image File history File links Please see the file description page for further information. ... Image File history File links Please see the file description page for further information. ... “Chiroptera” redirects here. ... Image File history File links This is a lossless scalable vector image. ... This article is about life in general. ... The term morphology in biology refers to the outward appearance (shape, structure, colour, pattern) of an organism or taxon and its component parts. ... This article or section does not cite any references or sources. ... This article does not cite any references or sources. ... For other uses, see Sleep (disambiguation). ... A bat illustrating nocturnal features. ... Lepidopteran on a flower. ... Subfamilies See Taxonomy section Crickets, family Gryllidae (also known as true crickets), are insects somewhat related to grasshoppers and more closely related to katydids or bush crickets (family Tettigoniidae). ... See Animal. ... For other uses, see Plant (disambiguation). ... Crassulacean Acid Metabolism (CAM) is a carbon fixation pathway in some photosynthetic plants. ... Carbon fixation is a process found in autotrophs, usually driven by photosynthesis, whereby carbon dioxide is changed into organic materials. ... Photosynthesis splits water to liberate O2 and fixes CO2 into sugar The leaf is the primary site of photosynthesis in plants. ... Carbon dioxide (chemical formula: ) is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... An organic acid is an organic compound that is an acid. ... Lactose is a disaccharide found in milk. ... This is not about surgically created bowel openings; see stoma (medicine) In botany, a stoma (also stomate; plural stomata) is a tiny opening or pore, found mostly on the undersurface of a plant leaf, and used for gas exchange. ... Transpiration is the evaporation of excess water from aerial parts and of plants, especially leaves but also stems, flowers and fruits. ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ...

Humans and the night

Social and economic factors

A busy street at nighttime

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Throughout the rest of history, night has primarily been a time of resting and sleep for humans, since little work or labor can be done in the dark. On the other hand, clandestine activities such as romance, sex, prostitution, and criminal and police activity flourish. Image File history File linksMetadata Download high-resolution version (2048x1536, 580 KB) Summary A black and White Picture of Oxford St in London, Ontario. ... Image File history File linksMetadata Download high-resolution version (2048x1536, 580 KB) Summary A black and White Picture of Oxford St in London, Ontario. ... Image File history File links This is a lossless scalable vector image. ... For other uses, see Sleep (disambiguation). ... Romance is a general term that refers to an intimate and often sexual relationship between two people. ... It has been suggested that Duration of sexual intercourse be merged into this article or section. ... Whore redirects here. ... For other uses, see Crime (disambiguation). ...

As artificial lighting has improved, especially after the Industrial Revolution, night-time activity has increased and become a significant part of the economy in most places. Many establishments, such as nightclubs, bars, convenience stores, fast-food restaurants, gas stations, distribution facilities, and police stations now operate 24 hours a day or stay open as late as 1 or 2 a.m. Even without artificial light, moonlight sometimes makes it possible to travel or work outdoors at night. Not to be confused with lightning. ... A Watt steam engine, the steam engine that propelled the Industrial Revolution in Britain and the world. ... Laser lights illuminate the dance floor at a Gatecrasher dance music event in Sheffield, England A nightclub (or night club or club) is a drinking, dancing, and entertainment venue which does its primary business after dark. ... Singles bar redirects here. ... This article does not cite any references or sources. ... This article is about Earths moon. ...

Cultural aspects

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Nótt, the Norse goddess of the night, rides her horse in this 19th century painting by Peter Nicolai Arbo.

Night is often associated with danger and evil, because bandits and dangerous animals can be concealed by darkness. The belief in magic often includes the idea that magic and magicians are more powerful at night. Similarly, mythical and folkloric creatures as vampires, and werewolves are thought to be more active at night. Ghosts are believed to wander around almost exclusively during night-time. In almost all cultures, there exist stories and legends warning of the dangers of night-time. In fact, the Saxons called the darkness of night the 'death mist'.^{[citation needed]} Image File history File links This is a lossless scalable vector image. ... Image File history File links Download high resolution version (750x977, 92 KB)Nótt riding Hrímfaxi. ... Image File history File links Download high resolution version (750x977, 92 KB)Nótt riding Hrímfaxi. ... Nótt rides her horse in this 19th century painting by Peter Nicolai Arbo. ... Alternative meaning: Nineteenth Century (periodical) (18th century — 19th century — 20th century — more centuries) As a means of recording the passage of time, the 19th century was that century which lasted from 1801-1900 in the sense of the Gregorian calendar. ... Peter Nicolai Arbo (1831–1892) was a Norwegian painter, who specialized in painting historical motifs and images from Norse mythology. ... The Sorceress by John William Waterhouse Magic, sometimes known as sorcery, is a conceptual system that asserts human ability to control the natural world (including events, objects, people, and physical phenomena) through mystical, paranormal or supernatural means. ... Philip Burne-Jones, The Vampire, 1897 Vampires are mythological or folkloric beings that subsist on human and/or animal lifeforce. ... For other uses, see Werewolf (disambiguation). ... For other uses, see Ghost (disambiguation). ...

See also

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Night

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• Earth clock
• Midnight
• Night sky
• Nightlife
• Nocturne
• Olbers' paradox

Image File history File links En-Night. ... Image File history File links Sound-icon. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 344th day of the year (345th in leap years) in the Gregorian calendar. ... For other uses, see Midnight (disambiguation) Midnight, literally the middle of the night, is a time arbitrarily designated to determine the end of a day and the beginning of the next in some, mainly Western, cultures. ... Amateur astronomy, often called back yard astronomy, is a hobby whose participants enjoy observing celestial objects. ... For other uses, see Nightlife (disambiguation). ... For the ancient form of Christian night prayer, see Nocturns. ... Olbers paradox, described by the German astronomer Heinrich Wilhelm Olbers in 1826 and earlier by Johannes Kepler in 1610 and Halley and Cheseaux in the 18th century, is the paradoxical observation that the night sky is dark, when in a static infinite universe the night sky ought to be bright. ...

References