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This article is about the star. For other uses, see Sun (disambiguation).[1][2]

The Sun [3]
[4]
Observation data
Mean distance

from Earth

1.496×108 km8 min 19 s at light speed
Visual brightness (V) −26.74 [1]
Absolute magnitude 4.83 [1]
Spectral classification G2V
Metallicity Z = 0.0122[2]
Angular size 31.6′ – 32.7′ [3]
Adjectives solar
Orbital characteristics
Mean distance

from Milky Way core

~2.5×1017 km26,000 light-years
Galactic period (2.25–2.50)×108 a
Velocity ~220 km/s (orbit around the center of the Galaxy)~20 km/s (relative to average velocity of other stars in stellar neighborhood)

~370 km/s[4] (relative to the cosmic microwave background)

Physical characteristics
Mean diameter 1.392×106 km [1]109 × Earth
Equatorial radius 6.955×105 km [5]109 × Earth[5]
Equatorial circumference 4.379×106 km [5]109 × Earth[5]
Flattening 9×10−6
Surface area 6.0877×1012 km2 [5]

11,990 × Earth[5]

Volume 1.412×1018 km3 [5]1,300,000 × Earth
Mass 1.9891×1030 kg[1]333,000 × Earth[1]
Average density 1.408×103 kg/m3 [1][5][6]
Density Center (model): 1.622×105 kg/m3 [1]Lower photosphere: 2×10−4 kg/m3

Lower chromosphere: 5×10−6 kg/m3 Corona (avg.): 1×10−12 kg/m3 [7]

Equatorial surface gravity 274.0 m/s2 [1]27.94 g

28 × Earth[5]

Escape velocity

(from the surface)

617.7 km/s [5]55 × Earth[5]
Temperature Center (modeled): ~1.57×107 K [1]Photosphere (effective): 5,778 K [1]

Corona: ~5×106 K

Luminosity (Lsol) 3.846×1026 W [1]~3.75×1028 lm

~98 lm/W efficacy

Mean Intensity (Isol) 2.009×107 W·m−2·sr−1
Rotation characteristics
Obliquity 7.25° [1](to the ecliptic)

67.23° (to the galactic plane)

Right ascension

of North pole[8]

286.13°

19h 4min 30s

Declination

of North pole

+63.87°

63°52' North

Sidereal rotation period(at equator) 25.05 days [1]
(at 16° latitude) 25.38 days [1]25d 9h 7min 12s [8]
(at poles) 34.4 days [1]
Rotation velocity

(at equator)

7.189×103 km/h [5]
Photospheric composition (by mass)
Hydrogen 73.46%[9]
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%
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The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields.[10][11] It has a diameter of about 1,392,000 km, about 109 times that of Earth, and its mass (about 2×1030 kilograms, 330,000 times that of Earth) accounts for about 99.86% of the total mass of the Solar System.[12] Chemically, about three quarters of the Sun's mass consists of hydrogen, while the rest is mostly helium. The remainder (1.69%, which nonetheless equals 5,628 times the mass of Earth) consists of heavier elements, including oxygen, carbon, neon and iron, among others.[13]

The Sun's stellar classification, based on spectral class, is G2V, and is informally designated as a yellow dwarf, because its visible radiation is most intense in the yellow-green portion of the spectrum and although its color is white, from the surface of the Earth it may appear yellow because of atmospheric scattering of blue light.[14][15] In the spectral class label, G2 indicates its surface temperature of approximately 5778 K (5505 °C), and V indicates that the Sun, like most stars, is a main-sequence star, and thus generates its energy by nuclear fusion of hydrogen nuclei into helium. In its core, the Sun fuses 620 million metric tons of hydrogen each second. Once regarded by astronomers as a small and relatively insignificant star, the Sun is now thought to be brighter than about 85% of the stars in the Milky Way galaxy, most of which are red dwarfs.[16][17] The 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 apparent magnitude of −26.74.[18][19] The Sun's hot corona continuously expands in space creating the solar wind, a stream of charged particles that extends to the heliopause at roughly 100 astronomical units. The bubble in the interstellar medium formed by the solar wind, the heliosphere, is the largest continuous structure in the Solar System.[20][21]

The Sun is currently traveling through the Local Interstellar Cloud in the Local Bubble zone, within the inner rim of the Orion Arm of the Milky Way galaxy. Of the 50 nearest stellar systems within 17 light-years from Earth (the closest being a red dwarf named Proxima Centauri at approximately 4.2 light years away), the Sun ranks fourth in mass.[22] The Sun orbits the center of the Milky Way at a distance of approximately 24,00026,000 light years from the galactic center, completing one clockwise orbit, as viewed from the galactic north pole, in about 225–250 million years. Since our galaxy is moving with respect to the cosmic microwave background radiation (CMB) in the direction of the constellation Hydra with a speed of 550 km/s, the Sun's resultant velocity with respect to the CMB is about 370 km/s in the direction of Crater or Leo.[23]

The mean distance of the Sun from the Earth is approximately 149.6 million kilometers (1 AU), though the distance varies as the Earth moves from perihelion in January to aphelion in July.[24] 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 photosynthesis,[25] and drives Earth's climate and weather. The enormous effect of the Sun on the Earth has been recognized since prehistoric 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 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 unexplained.

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