Late summer dawn over theMojave Desert,CaliforniaDawn is sometimes considered the beginning of morningtwilight, the period of twilight, or the time of sunrise.
Dawn begins with the first sight of lightness in the morning, and continues until the Sun breaks the horizon. The morning twilight is divided in three phases, which are determined by the angular distance of the centre of the Sun (degrees below the horizon) in themorning. These are astronomical, nautical and civil twilight.
Astronomical dawn begins when the center of the Sun is 18degrees below the horizon in the morning. Astronomical twilight follows instantly until the center of the Sun is 12degrees below the horizon.[5] At this point, a very small portion of the Sun's rays illuminate the sky and the fainter stars begin to disappear. Astronomical dawn is often indistinguishable from night, especially in areas withlight pollution. Astronomical dawn marks the beginning of astronomical twilight, which lasts until nautical dawn.[6]
Nautical twilight begins when there is enough light for sailors to distinguish the horizon at sea, but the sky is still too dark to perform outdoor activities. It begins when the center of the Sun is 12 degrees below the horizon in the morning. Nautical dawn marks the start of nautical twilight, which lasts until civil dawn.[6][5]
Civil dawn begins when there is enough light for most objects to be distinguishable, so that some outdoor activities can commence. It occurs when the center of theSun is 6 degrees below the horizon in the morning.[5]
When the sky is clear, it is blue colored, and if there are clouds or haze, then bronze, orange and yellow colors are seen. Some brightstars andplanets such as Venus and Jupiter are still visible to the naked eye at civil dawn. This moment marks the start of civil twilight, which lasts untilsunrise.[6]
The duration of the morningtwilight (i.e. between astronomical dawn andsunrise) varies greatly depending on the observer'slatitude: from a little over 70 minutes at theEquator, to many hours in thepolar regions.[7][8]
The period of twilight is shortest at theEquator, where theequinox Sun rises due east and sets due west, at aright angle to the horizon. Each stage of twilight (civil, nautical, and astronomical) lasts only 24 minutes. From anywhere on Earth, the twilight period is shortest around the equinoxes and longest on thesolstices.[citation needed]
Daytime becomes longer as thesummer solstice approaches, whilenighttime gets longer as thewinter solstice approaches. This can have a potential impact on the times and durations of dawn and dusk. This effect is more pronounced closer to the poles, where the Sun rises at the vernal equinox and sets at the autumn equinox, with a long period of twilight, lasting for a few weeks.[citation needed]
Thepolar circle (at 66°33′50.8″ north or south) is defined as the lowest latitude at which the Sun does not set at thesummer solstice. Therefore, theangular radius of the polar circle is equal to the angle between Earth's equatorial plane and theecliptic plane. This period of time with nosunset lengthens closer to the pole.[citation needed]
At latitudes higher than about 60°34′, summer nights get no darker than civil twilight. This period of "bright nights" is longer at higher latitudes.[citation needed]
Near the summer solstice, latitudes higher than about 54°34′ get no darker than nautical twilight; the "darkness of the night" varies greatly at these latitudes.[citation needed]
Around thesummer solstice, Glasgow, Scotland at 55°51′ N, and Copenhagen, Denmark at 55°40′ N, get a few hours of "night feeling". Oslo, Norway at 59°56′ N, and Stockholm, Sweden at 59°19′ N, seem very bright when the Sun is below the horizon. When the Sun gets 9.0 to 9.5 degrees below the horizon (at summer solstice this is at latitudes 57°30′–57°00′), the zenith gets dark even on cloud-free nights (if there is no full moon), and the brightest stars are clearly visible in a large majority of the sky.[citation needed]
InIslam,Zodiacal Light is referred to as False Dawn (Al-Fajr Al-Kadhib,Arabicالفجر الكاذب) andAstronomical dawn is called True Dawn (Al-Fajr As-Sadiq, Arabicالفجر الصادق), and it is the time of first prayer of the day, and the beginning of the daily fast duringRamadan.[9]
TheHindu dawn deityUshas is female, whereasSurya, the Sun, andAruṇa, the Sun's charioteer, are male.Ushas is one of the most prominentRigvedic deities. The time of dawn is also referred to as thebrahmamuhurta (Brahma is the god of creation andmuhurta is a Hindu time of the day), and is considered an ideal time to perform spiritual activities, including meditation andyoga. In some parts ofIndia, both Usha and Pratyusha (dusk) are worshipped along with the Sun during the festival ofChhath.[citation needed]
Jesus in the Bible is often symbolized by dawn in the morning, also when Jesus rose on the third day it happened during the morning.[10]Prime is the fixed time of prayer of the traditionalDivine Office (Canonical Hours) inChristian liturgy, said at the first hour of daylight. Associated with Jesus, in Christianity,Christian burials take place in the direction of dawn.[citation needed]
InJudaism, the question of how to calculate dawn (Hebrew Alos/Alot HaShachar, or Alos/Alot) is posed by theTalmud,[11] as it has many ramifications for Jewish law (such as the possible start time for certain daytime commandments, like prayer). The simple reading of the Talmud is that dawn takes place 72 minutes before sunrise. Others, including theVilna Gaon, have the understanding that the Talmud's timeframe for dawn was referring specifically to an equinox day inMesopotamia, and is therefore teaching that dawn should be calculated daily as commencing when the Sun is 16.1 degrees below the horizon. The longstanding practice among mostSephardic Jews is to follow the first opinion, while manyAshkenazi Jews follow the latter view.[citation needed]
Anaubade (OccitanAlba, GermanTagelied) is a song about lovers having to separate at daybreak
Aurora Musis amica (Dawn is a friend to theMuse), inEpigrammata Disticha Poetarum Latinorum, Veterum et Recentum, Nobiliora (1642) byBarthold Nihus[12]
The Dawn, volume 1 onJean-Christophe written byRomain Rolland
"Dawn", a four-line poem fromLyrics of Lowly Life, a book of poetry written byPaul Laurence Dunbar, originally published in 1896. This poem was published again inThe Complete Poems of Paul Laurence Dunbar, the 1913 collection of his work--
