The Sun is the star at the center of the Solar System. It is a nearly perfect sphere of hot plasma,[18][19] heated to incandescence by nuclear fusion reactions in its core. It radiates the energy mainly as visible light, ultraviolet light, and infrared radiation. It is by far the most important source of energy for life on Earth. Its diameter is about 1.39 million kilometers (864,000 miles), or 109 times that of Earth. Its mass is about 330,000 times that of Earth; it accounts for about 99.86% of the Solar System's total mass.[20] Roughly 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.[21]
Details of sun 🌞
Names
Sun, Sol /ˈsɒl/,[1] Sól, Helios /ˈhiːliəs/[2]
Adjectives
Solar /ˈsoʊlər/[3]
Observation data
Mean distance
from Earth
1 AU ≈ 1.496×108 km[4]
8 min 19 s at light speed
Visual brightness (V)
−26.74[5]
Absolute magnitude
4.83[5]
Spectral classification
G2V[6]
Metallicity
Z = 0.0122[7]
Angular size
31.6–32.7 minutes of arc[8]
≈ 0.5 degrees
Orbital characteristics
Mean distance
from Milky Way core
≈ 2.7×1017 km
≈ 29,000 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 the average velocity of other stars in the stellar neighborhood)
≈ 370 km/s[9] (relative to the cosmic microwave background)
Physical characteristics
Equatorial radius
695,700 km,[10]
696,342 km[11]
109 × Earth radii[12]
Equatorial circumference
4.379×106 km[12]
109 × Earth[12]
Flattening
9×10−6
Surface area
6.09×1012 km2[12]
12,000 × Earth[12]
Volume
1.41×1018 km3[12]
1,300,000 × Earth
Mass
1.9885×1030 kg[5]
333,000 Earths[5]
Average density
1.408 g/cm3[5][12][13]
0.255 × Earth[5][12]
Center density (modeled)
162.2 g/cm3[5]
12.4 × Earth
Equatorial surface gravity
274 m/s2[5]
28 × Earth[12]
Moment of inertia factor
0.070[5] (estimate)
Escape velocity
(from the surface)
617.7 km/s[12]
55 × Earth[12]
Temperature
Center (modeled): 1.57×107 K[5]
Photosphere (effective): 5,772 K[5]
Corona: ≈ 5×106 K
Luminosity (Lysol)
3.828×1026 W[5]
≈ 3.75×1028 lm
≈ 98 lm/W efficacy
Color (B-V)
0.63
Mean radiance (Isol)
2.009×107 W·m−2·sr−1
Age
≈ 4.6 billion years (4.6×109 years) [14][15]
Rotation characteristics
Obliquity
7.25°[5]
(to the ecliptic)
67.23°
(to the galactic plane)
Right ascension
of North pole[16]
286.13°
19 h 4 min 30 s
Declination
of North pole
+63.87°
63° 52' North
Sidereal rotation period
(at the equator)
25.05 d[5]
(at 16° latitude)
25.38 d[5]
25 d 9 h 7 min 12 s[16]
(at poles)
34.4 d[5]
Rotation velocity
(at the equator)
7.189×103 km/h[12]
Photospheric composition (by mass)
Hydrogen
73.46%[17]
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%
Shape and size of sun 🌞
The Sun is a G-type main-sequence star (G2V) based on its spectral class. It is informally and not completely accurately referred to as a yellow dwarf (its light is closer to white than yellow). It formed approximately 4.6 billion[a][14][22] 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's core fuses about 600 million tons of hydrogen into helium every second, converting 4 million tons of matter into energy every second as a result. This energy, which can take between 10,000 and 170,000 years to escape the core, is the Sun's light and heat source. When hydrogen fusion in its core has diminished to the point at which the Sun is no longer in hydrostatic equilibrium, its core will undergo a marked increase in density and temperature. At the same time, its outer layers expand, eventually transforming the Sun into a red giant. After this, it will shed its outer layers and become a dense cooling star known as a white dwarf, and no longer produces energy by fusion but still glow and give off heat from its previous fusion. It is calculated that the Sun will become sufficiently large to engulf the current orbits of Mercury and Venus and render Earth uninhabitable – but not for about five billion years.
The enormous effect of the Sun on Earth has been recognized since prehistoric times. The Sun was thought of 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 Gregorian calendar, the predominant calendar in use today.
Why is it so hot 🔥?
The sun's core is so hot, and there is so much pressure, nuclear fusion takes place: hydrogen is changed to helium. Nuclear fusion creates heat and photons (light). The sun's surface is about 6,000 Kelvin, 10,340 degrees Fahrenheit (5,726 degrees Celsius).
Position of sun.
The Sun, and everything that orbits it, is located in the Milky Way galaxy. Our Sun is in a spiral arm called the Orion Spur that extends outward from the Sagittarius arm.
Gases present on Sun.
A tiny percentage (1.69 percent) of the sun's mass comprises other gases and metals: iron, nickel, oxygen, silicon, sulfur, magnesium, carbon, neon, calcium, and chromium. This 1.69 percent may seem insignificant, but its mass is still 5,628 times the mass of Earth. The sun is not a solid mass.
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