Sun

The Sun Sun symbol.svg
Sun white.jpg
Sun with sunspots and limb darkening as seen in visible light with solar filter.
Observation data
Mean distance
from Earth
1 au1.496×108 km
8 min 19 s at light speed
Visual brightness (V) −26.74 [1]
Absolute magnitude 4.83 [1]
Spectral classification G2V [2]
Metallicity Z = 0.0122 [3]
Angular size 31.6–32.7 minutes of arc [4]
Adjectives Solar
Orbital characteristics
Mean distance
from Milky Way core
≈ 2.7×1017 km
27,200  light-years
Galactic period (2.25–2.50)×108 yr
Velocity ≈ 220 km/s (orbit around the center of the Milky Way)
≈ 20 km/s (relative to average velocity of other stars in stellar neighborhood)
≈ 370 km/s [5] (relative to the cosmic microwave background)
Physical characteristics
Equatorial radius 695,700 km [6],
696,392 km [7]
109  × Earth [8]
Equatorial circumference 4.379×106 km [8]
109 × Earth [8]
Flattening 9×10−6
Surface area 6.09×1012 km2 [8]
12,000 × Earth [8]
Volume 1.41×1018 km3 [8]
1,300,000 × Earth
Mass (1.98855±0.00025)×1030 kg [1]
333,000  × Earth [1]
Average density 1.408 g/cm3 [1] [8] [9]
0.255 × Earth [1] [8]
Center density (modeled) 162.2 g/cm3 [1]
12.4 × Earth
Equatorial surface gravity 274.0 m/s2 [1]
27.94  g
27,542.29  cgs
28 × Earth [8]
Moment of inertia factor 0.070 [1] (estimate)
Escape velocity
(from the surface)
617.7 km/s [8]
55 × Earth [8]
Temperature Center (modeled): 1.57×107 K [1]
Photosphere (effective): 5,772  K [1]
Corona: ≈ 5×106 K
Luminosity (Lsol) 3.828×1026  W [1]
≈ 3.75×1028  lm
≈ 98 lm/W efficacy
Mean radiance (Isol) 2.009×107 W·m−2·sr−1
Age ≈ 4.6 billion years [10] [11]
Rotation characteristics
Obliquity 7.25° [1]
(to the ecliptic)
67.23°
(to the galactic plane)
Right ascension
of North pole [12]
286.13°
19 h 4 min 30 s
Declination
of North pole
+63.87°
63° 52' North
Sidereal rotation period
(at equator)
25.05 d [1]
(at 16° latitude) 25.38 d [1]
25 d 9 h 7 min 12 s [12]
(at poles) 34.4 d [1]
Rotation velocity
(at equator)
7.189×103 km/h [8]
Photospheric composition (by mass)
Hydrogen 73.46% [13]
Helium 24.85%
Oxygen 0.77%
Carbon 0.29%
Iron 0.16%
Neon 0.12%
Nitrogen 0.09%
Silicon 0.07%
Magnesium 0.05%
Sulfur 0.04%

The Sun is the star at the center of the Solar System. It is a nearly perfect sphere of hot plasma, [14] [15] with internal convective motion that generates a magnetic field via a dynamo process. [16] It is by far the most important source of energy for life on Earth. Its diameter is about 1.39 million kilometers, i.e. 109 times that of Earth, and its mass is about 330,000 times that of Earth, accounting for about 99.86% of the total mass of the Solar System. [17] About three quarters of the Sun's mass consists of hydrogen (~73%); the rest is mostly helium (~25%), with much smaller quantities of heavier elements, including oxygen, carbon, neon, and iron. [18]

The Sun is a G-type main-sequence star (G2V) based on its spectral class. As such, it is informally referred to as a yellow dwarf. It formed approximately 4.6 billion [a] [10] [19] years ago from the gravitational collapse of matter within a region of a large molecular cloud. Most of this matter gathered in the center, whereas the rest flattened into an orbiting disk that became the Solar System. The central mass became so hot and dense that it eventually initiated nuclear fusion in its core. It is thought that almost all stars form by this process.

The Sun is roughly middle-aged; it has not changed dramatically for more than four billion [a] years, and will remain fairly stable for more than another five billion years. After hydrogen fusion in its core has diminished to the point at which it is no longer in hydrostatic equilibrium, the core of the Sun will experience a marked increase in density and temperature while its outer layers expand to eventually become a red giant. It is calculated that the Sun will become sufficiently large to engulf the current orbits of Mercury and Venus, and render Earth uninhabitable.

The enormous effect of the Sun on Earth has been recognized since prehistoric times, and the Sun has been regarded by some cultures as a deity. The synodic rotation of Earth and its orbit around the Sun are the basis of solar calendars, one of which is the predominant calendar in use today.

Name and etymology

The English proper name Sun developed from Old English sunne and may be related to south. Cognates to English sun appear in other Germanic languages, including Old Frisian sunne, sonne, Old Saxon sunna, Middle Dutch sonne, modern Dutch zon, Old High German sunna, modern German Sonne, Old Norse sunna, and Gothic sunnō. All Germanic terms for the Sun stem from Proto-Germanic *sunnōn. [20] [21]

The English weekday name Sunday stems from Old English (Sunnandæg; "Sun's day", from before 700) and is ultimately a result of a Germanic interpretation of Latin dies solis, itself a translation of the Greek ἡμέρα ἡλίου (hēméra hēlíou). [22] The Latin name for the Sun, Sol, is not common in general English language use; the adjectival form is the related word solar. [23] [24] The term sol is also used by planetary astronomers to refer to the duration of a solar day on another planet, such as Mars. [25] A mean Earth solar day is approximately 24 hours, whereas a mean Martian 'sol' is 24 hours, 39 minutes, and 35.244 seconds. [26]

Religious aspects

Solar deities play a major role in many world religions and mythologies. [27] The ancient Sumerians believed that the sun was Utu, [28] [29] the god of justice and twin brother of Inanna, the Queen of Heaven, [28] who was identified as the planet Venus. [29] Later, Utu was identified with the East Semitic god Shamash. [28] [29] Utu was regarded as a helper-deity, who aided those in distress, [28] and, in iconography, he is usually portrayed with a long beard and clutching a saw, [28] which represented his role as the dispenser of justice. [28]

From at least the 4th Dynasty of Ancient Egypt, the Sun was worshipped as the god Ra, portrayed as a falcon-headed divinity surmounted by the solar disk, and surrounded by a serpent. In the New Empire period, the Sun became identified with the dung beetle, whose spherical ball of dung was identified with the Sun. In the form of the Sun disc Aten, the Sun had a brief resurgence during the Amarna Period when it again became the preeminent, if not only, divinity for the Pharaoh Akhenaton. [30] [31]

In Proto-Indo-European religion, the sun was personified as the goddess *Seh2ul. [32] [33] [21] Derivatives of this goddess in Indo-European languages include the Old Norse Sól, Sanskrit Surya, Gaulish Sulis, Lithuanian Saulė, and Slavic Solntse. [21] In ancient Greek religion, the sun deity was the male god Helios, [32] but traces of an earlier female solar deity are preserved in Helen of Troy. [32] In later times, Helios was syncretized with Apollo. [34]

In the Bible, Malachi 4:2 mentions the "Sun of Righteousness" (sometimes translated as the "Sun of Justice"), [35] which some Christians have interpreted as a reference to the Messiah ( Christ). [36] In ancient Roman culture, Sunday was the day of the Sun god. It was adopted as the Sabbath day by Christians who did not have a Jewish background. The symbol of light was a pagan device adopted by Christians, and perhaps the most important one that did not come from Jewish traditions. In paganism, the Sun was a source of life, giving warmth and illumination to mankind. It was the center of a popular cult among Romans, who would stand at dawn to catch the first rays of sunshine as they prayed. The celebration of the winter solstice (which influenced Christmas) was part of the Roman cult of the unconquered Sun ( Sol Invictus). Christian churches were built with an orientation so that the congregation faced toward the sunrise in the East. [37]

Tonatiuh, the Aztec god of the sun, was usually depicted holding arrows and a shield [38] and was closely associated with the practice of human sacrifice. [38] The sun goddess Amaterasu is the most important deity in the Shinto religion, [39] [40] and she is believed to be the direct ancestor of all Japanese emperors. [39]

Other Languages
адыгабзэ: Тыгъэ
Afrikaans: Son
Akan: Ewia
Alemannisch: Sonne
አማርኛ: ፀሐይ
Ænglisc: Sunne
Аҧсшәа: Амра
العربية: الشمس
aragonés: Sol
ܐܪܡܝܐ: ܫܡܫܐ
armãneashti: Soari
arpetan: Solely
অসমীয়া: সূৰ্য
asturianu: Sol
Atikamekw: Pisimw
Avañe'ẽ: Kuarahy
авар: Бакъ
Aymar aru: Willka
azərbaycanca: Günəş
تۆرکجه: گونش
বাংলা: সূর্য
Bahasa Banjar: Matahari
Bân-lâm-gú: Ji̍t-thâu
Basa Banyumasan: Srengenge
башҡортса: Ҡояш
беларуская: Сонца
беларуская (тарашкевіца)‎: Сонца
भोजपुरी: सुरुज
Bikol Central: Saldang
български: Слънце
Boarisch: Sun
བོད་ཡིག: ཉི་མ།
bosanski: Sunce
brezhoneg: Heol
буряад: Наран
català: Sol
Чӑвашла: Хĕвел
Cebuano: Adlaw
čeština: Slunce
chiShona: Zuva
chiTumbuka: Zuwa
corsu: Soli
Cymraeg: Haul
dansk: Solen
davvisámegiella: Beaivváš
Deitsch: Sunn
Deutsch: Sonne
ދިވެހިބަސް: އިރު
Diné bizaad: Jóhonaaʼéí
eesti: Päike
Ελληνικά: Ήλιος
emiliàn e rumagnòl: Såul
español: Sol
Esperanto: Suno
estremeñu: Sol
euskara: Eguzkia
فارسی: خورشید
Fiji Hindi: Suraj
føroyskt: Sólin
français: Soleil
Frysk: Sinne
Fulfulde: Naange
furlan: Soreli
Gaeilge: An Ghrian
Gaelg: Yn Ghrian
Gàidhlig: Grian
galego: Sol
贛語: 太陽
ગુજરાતી: સૂર્ય
𐌲𐌿𐍄𐌹𐍃𐌺: 𐍃𐌿𐌽𐌽𐍉
客家語/Hak-kâ-ngî: Ngit-tèu
хальмг: Нарн
한국어: 태양
Hausa: Rana
Hawaiʻi:
Հայերեն: Արեգակ
हिन्दी: सूर्य
hrvatski: Sunce
Ido: Suno
Ilokano: Init
Bahasa Indonesia: Matahari
interlingua: Sol
Interlingue: Sole
ᐃᓄᒃᑎᑐᑦ/inuktitut: ᓯᕿᓂᖅ
Iñupiak: Siqiñiq
Ирон: Хур
isiXhosa: UKat
isiZulu: Ilanga
íslenska: Sólin
italiano: Sole
עברית: השמש
Basa Jawa: Srengéngé
ಕನ್ನಡ: ಸೂರ್ಯ
Kapampangan: Aldo
къарачай-малкъар: Кюн
ქართული: მზე
kaszëbsczi: Słuńce
қазақша: Күн (жұлдыз)
kernowek: Howl
Kiswahili: Jua
коми: Шонді
Kongo: Ntangu
Kreyòl ayisyen: Solèy
Kurdî: Roj (stêrk)
Кыргызча: Күн
Ladino: Sol
лезги: Рагъ
latgaļu: Saule
Latina: Sol
latviešu: Saule
Lëtzebuergesch: Sonn
lietuvių: Saulė
Ligure:
Limburgs: Zon
lingála: Mói
Livvinkarjala: Päiväine
la .lojban.: solri
lumbaart: Suu
magyar: Nap
मैथिली: सूर्य
македонски: Сонце
Malagasy: Masoandro
മലയാളം: സൂര്യൻ
Malti: Xemx
मराठी: सूर्य
მარგალური: ბჟა
مصرى: الشمس
مازِرونی: خورشید
Bahasa Melayu: Matahari
Mìng-dĕ̤ng-ngṳ̄: Nĭk-tàu
Mirandés: Sol
мокшень: Шись
монгол: Нар
မြန်မာဘာသာ: နေ
Nāhuatl: Tōnatiuh
Dorerin Naoero: Ekwan
Nederlands: Zon
Nedersaksies: Zunne
Nēhiyawēwin / ᓀᐦᐃᔭᐍᐏᐣ: ᒌᔑᑳᐅᐲᓯᒽ
नेपाली: सूर्य
नेपाल भाषा: सूर्द्य
日本語: 太陽
Napulitano: Sole
нохчийн: Малх
Nordfriisk: San
norsk: Solen
norsk nynorsk: Sola
Nouormand: Solé
Novial: Sune
occitan: Soleu
ଓଡ଼ିଆ: ସୂର୍ଯ୍ୟ
oʻzbekcha/ўзбекча: Quyosh
ਪੰਜਾਬੀ: ਸੂਰਜ
Pälzisch: Sunn
پنجابی: سورج
Papiamentu: Solo
پښتو: لمر
Patois: Son
Перем Коми: Шонді
ភាសាខ្មែរ: ព្រះអាទិត្យ
Picard: Solel
Piemontèis: Sol
Tok Pisin: San
Plattdüütsch: Sünn
polski: Słońce
Ποντιακά: Ήλος
português: Sol
Qaraqalpaqsha: Quyash
qırımtatarca: Küneş
Ripoarisch: Sunn
română: Soare
Romani: Kham
rumantsch: Sulegl
Runa Simi: Inti
русиньскый: Сонце
русский: Солнце
саха тыла: Күн (сулус)
संस्कृतम्: सूर्यः
sardu: Sole
Scots: Sun
Seeltersk: Sunne
shqip: Dielli
sicilianu: Suli
සිංහල: හිරු
Simple English: Sun
سنڌي: سج
slovenčina: Slnko
slovenščina: Sonce
словѣньскъ / ⰔⰎⰑⰂⰡⰐⰠⰔⰍⰟ: Слъньцє
ślůnski: Słůńce
Soomaaliga: Qorax
کوردی: خۆر
српски / srpski: Сунце
srpskohrvatski / српскохрватски: Sunce
Basa Sunda: Panonpoé
suomi: Aurinko
svenska: Solen
Taqbaylit: Tafukt
татарча/tatarça: Кояш
తెలుగు: సూర్యుడు
тоҷикӣ: Офтоб
ᏣᎳᎩ: ᏅᏓ
Tsetsêhestâhese: Éše'he
ತುಳು: ಸೂರ್ಯ
Türkçe: Güneş
Türkmençe: Gün (ýyldyz)
Twi: Ewia
тыва дыл: Хүн (сылдыс)
удмурт: Шунды
українська: Сонце
اردو: سورج
ئۇيغۇرچە / Uyghurche: قۇياش
Vahcuengh: Daengngoenz
vèneto: Sołe
vepsän kel’: Päiväine
Tiếng Việt: Mặt Trời
Volapük: Sol
Võro: Päiv
walon: Solea
文言:
West-Vlams: Zunne
Wolof: Jant
吴语: 太陽
ייִדיש: זון
Yorùbá: Òrùn
粵語: 太陽
Zazaki: Tici
Zeêuws: Zunne
žemaitėška: Saulė
中文: 太阳
डोटेली: सूर्य
Kabɩyɛ: Wɩsɩ