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[[File:lighterstill.jpg]][[File:The_sun_solar.jpg|right|frame]]

[[File:lighterstill.jpg]][[File:The_sun_solar.jpg|right|frame]]

'''The Sun''' is the [[star]] at the [[center]] of [[Earth]]'s [[Solar System]]. The Sun has a [[diameter]] of about 1,392,000 kilometers (865,000 mi) (about 109 Earths). Its mass (about 2 × 10 30th power kilograms, 330,000 times that of Earth) and by itself accounts for about 99.86% of the Solar System's [[mass]]; the remainder consists of the planets (including Earth), [http://en.wikipedia.org/wiki/Asteroid asteroids], [http://en.wikipedia.org/wiki/Meteoroid meteoroids], [http://en.wikipedia.org/wiki/Comet comets], and dust in [[orbit]]. About three-quarters of the Sun's mass consists of [http://en.wikipedia.org/wiki/Hydrogen hydrogen], while most of the rest is [http://en.wikipedia.org/wiki/Helium helium]. Less than 2% consists of other elements, including [http://en.wikipedia.org/wiki/Iron iron], [http://en.wikipedia.org/wiki/Oxygen oxygen], [http://en.wikipedia.org/wiki/Carbon carbon], [http://en.wikipedia.org/wiki/Neon neon], and others.

'''The Sun''' is the [[star]] at the [[center]] of [[Earth]]'s [[Solar System]]. The Sun has a [[diameter]] of about 1,392,000 kilometers (865,000 mi) (about 109 Earths). Its mass (about 2 × 10 30th power kilograms, 330,000 times that of Earth) and by itself accounts for about 99.86% of the Solar System's [[mass]]; the remainder consists of the planets (including Earth), [https://en.wikipedia.org/wiki/Asteroid asteroids], [https://en.wikipedia.org/wiki/Meteoroid meteoroids], [https://en.wikipedia.org/wiki/Comet comets], and dust in [[orbit]]. About three-quarters of the Sun's mass consists of [https://en.wikipedia.org/wiki/Hydrogen hydrogen], while most of the rest is [https://en.wikipedia.org/wiki/Helium helium]. Less than 2% consists of other elements, including [https://en.wikipedia.org/wiki/Iron iron], [https://en.wikipedia.org/wiki/Oxygen oxygen], [https://en.wikipedia.org/wiki/Carbon carbon], [https://en.wikipedia.org/wiki/Neon neon], and others.

The Sun's [[color]] is white, although from the [[surface]] of the [[Earth]] it may appear yellow because of atmospheric [http://en.wikipedia.org/wiki/Scattering scattering]. Its [http://en.wikipedia.org/wiki/Stellar_classification stellar classification], based on spectral class, is G2V, and is informally designated a yellow star, because the majority of its radiation is in the yellow-green portion of the visible spectrum. In this spectral class label, G2 indicates its surface temperature of approximately 5,778 K (5,505 °C), and V (Roman five) indicates that the Sun, like most stars, is a [http://en.wikipedia.org/wiki/Main_sequence main sequence star], and thus generates its [[energy]] by [http://en.wikipedia.org/wiki/Nuclear_fusion nuclear fusion] of hydrogen nuclei into helium.  

The Sun's [[color]] is white, although from the [[surface]] of the [[Earth]] it may appear yellow because of atmospheric [https://en.wikipedia.org/wiki/Scattering scattering]. Its [https://en.wikipedia.org/wiki/Stellar_classification stellar classification], based on spectral class, is G2V, and is informally designated a yellow star, because the majority of its radiation is in the yellow-green portion of the visible spectrum. In this spectral class label, G2 indicates its surface temperature of approximately 5,778 K (5,505 °C), and V (Roman five) indicates that the Sun, like most stars, is a [https://en.wikipedia.org/wiki/Main_sequence main sequence star], and thus generates its [[energy]] by [https://en.wikipedia.org/wiki/Nuclear_fusion nuclear fusion] of hydrogen nuclei into helium.  

Once regarded by [[astronomers]] as a small and [[relatively]] insignificant star, the Sun is now presumed to be brighter than about 85% of the stars in the [[Milky Way]] [[galaxy]], most of which are [http://en.wikipedia.org/wiki/Red_dwarf red dwarfs]. The [http://en.wikipedia.org/wiki/Absolute_magnitude absolute magnitude] of the Sun is +4.83; however, as the star closest to Earth, the Sun is the brightest object in the sky with an [http://en.wikipedia.org/wiki/Apparent_magnitude apparent magnitude] of –26.74.[15][16] The Sun's hot [http://en.wikipedia.org/wiki/Corona corona] continuously expands in [[space]] creating the solar wind, a hypersonic stream of charged particles that extends to the heliopause at roughly 100 AU. The bubble in the [http://en.wikipedia.org/wiki/Interstellar_medium interstellar medium] formed by the solar wind, the heliosphere, is the largest [[continuous]] [[structure]] in the Solar System.

Once regarded by [[astronomers]] as a small and [[relatively]] insignificant star, the Sun is now presumed to be brighter than about 85% of the stars in the [[Milky Way]] [[galaxy]], most of which are [https://en.wikipedia.org/wiki/Red_dwarf red dwarfs]. The [https://en.wikipedia.org/wiki/Absolute_magnitude absolute magnitude] of the Sun is +4.83; however, as the star closest to Earth, the Sun is the brightest object in the sky with an [https://en.wikipedia.org/wiki/Apparent_magnitude apparent magnitude] of –26.74.[15][16] The Sun's hot [https://en.wikipedia.org/wiki/Corona corona] continuously expands in [[space]] creating the solar wind, a hypersonic stream of charged particles that extends to the heliopause at roughly 100 AU. The bubble in the [https://en.wikipedia.org/wiki/Interstellar_medium interstellar medium] formed by the solar wind, the heliosphere, is the largest [[continuous]] [[structure]] in the Solar System.

The Sun is currently traveling through the [http://en.wikipedia.org/wiki/Local_Interstellar_Cloud Local Interstellar Cloud] in the [http://en.wikipedia.org/wiki/Local_Bubble Local Bubble zone], within the inner rim of the [http://en.wikipedia.org/wiki/Orion_Arm Orion Arm] of the [[Milky Way]] [[galaxy]]. Of the 50 nearest stellar systems within 17 [[light-years]] from [[Earth]], the Sun ranks 4th in [[mass]]. The Sun orbits the center of the Milky Way at a distance of approximately 24,000–26,000 [[light years]] from the [http://en.wikipedia.org/wiki/Galactic_center galactic center], completing one clockwise orbit, as viewed from the [http://en.wikipedia.org/wiki/Galactic_coordinates galactic north pole], in about 225–250 million years.

The Sun is currently traveling through the [https://en.wikipedia.org/wiki/Local_Interstellar_Cloud Local Interstellar Cloud] in the [https://en.wikipedia.org/wiki/Local_Bubble Local Bubble zone], within the inner rim of the [https://en.wikipedia.org/wiki/Orion_Arm Orion Arm] of the [[Milky Way]] [[galaxy]]. Of the 50 nearest stellar systems within 17 [[light-years]] from [[Earth]], the Sun ranks 4th in [[mass]]. The Sun orbits the center of the Milky Way at a distance of approximately 24,000–26,000 [[light years]] from the [https://en.wikipedia.org/wiki/Galactic_center galactic center], completing one clockwise orbit, as viewed from the [https://en.wikipedia.org/wiki/Galactic_coordinates galactic north pole], in about 225–250 million years.

The mean distance of the Sun from the Earth is approximately 149.6 million kilometers (1 AU), though this varies as the Earth moves from [http://en.wikipedia.org/wiki/Perihelion perihelion] in January to [http://en.wikipedia.org/wiki/Aphelion aphelion] in July. At this average distance, [[light]] travels from the Sun to [[Earth]] in about 8 minutes and 19 seconds. The energy of this sunlight supports almost all life on Earth by [http://en.wikipedia.org/wiki/Photosynthesis photosynthesis], and drives Earth's climate and weather. The enormous effect of the Sun on the Earth has been recognized since [http://en.wikipedia.org/wiki/Prehistory pre-historic times], and the Sun has been regarded by some [[cultures]] as a [[deity]]. An accurate [[scientific]] [[understanding]] of the Sun [[developed]] slowly, and as recently as the [http://www.wikipedia.org/wiki/19th_Century 19th century] prominent [[scientists]] had little [[knowledge]] of the Sun's [[physical]] composition and [[source]] of energy. This understanding is still developing; there are a [[number]] of present-day [[anomalies]] in the Sun's [[behavior]] that remain [[Unknown|unexplained]].

The mean distance of the Sun from the Earth is approximately 149.6 million kilometers (1 AU), though this varies as the Earth moves from [https://en.wikipedia.org/wiki/Perihelion perihelion] in January to [https://en.wikipedia.org/wiki/Aphelion aphelion] in July. At this average distance, [[light]] travels from the Sun to [[Earth]] in about 8 minutes and 19 seconds. The energy of this sunlight supports almost all life on Earth by [https://en.wikipedia.org/wiki/Photosynthesis photosynthesis], and drives Earth's climate and weather. The enormous effect of the Sun on the Earth has been recognized since [https://en.wikipedia.org/wiki/Prehistory pre-historic times], and the Sun has been regarded by some [[cultures]] as a [[deity]]. An accurate [[scientific]] [[understanding]] of the Sun [[developed]] slowly, and as recently as the [https://www.wikipedia.org/wiki/19th_Century 19th century] prominent [[scientists]] had little [[knowledge]] of the Sun's [[physical]] composition and [[source]] of energy. This understanding is still developing; there are a [[number]] of present-day [[anomalies]] in the Sun's [[behavior]] that remain [[Unknown|unexplained]].

[[Category: Astronomy]]

[[Category: Astronomy]]