cover image


star at the centre of the Solar System / From Wikipedia, the free encyclopedia

The Sun, also known as Sol, is a star at the center of our solar system. It is a white star that gives off different types of energy such as infrared energy (heat), ultraviolet light, radio waves and light. It also gives off a stream of particles, which reaches Earth as "solar wind". The source of all this energy is nuclear fusion. Nuclear fusion is the reaction in the star which turns hydrogen into helium and makes huge amounts of energy. It is a nearly perfect ball of hot plasma.

Quick facts: Observation data, Mean distance from Earth, V...
Sun ☉
Sun with sunspots and limb darkening as seen in visible light with solar filter.
False-color photo of the Sun as seen in ultraviolet light (wavelength of 30.4 nm)
Observation data
Mean distance
from Earth
1 au1.496×108 km[1]
8 min 19 s at light speed
Visual brightness (V)−26.74[2]
Absolute magnitude4.83[2]
Spectral classificationG2V[3]
MetallicityZ = 0.0122[4]
Angular size31.6–32.7 minutes of arc[5]
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[6] (relative to the cosmic microwave background)
Physical characteristics
Equatorial radius695,700 km,[7]
696,342 km[8]
109 × Earth[9]
Equatorial circumference4.379×106 km[9]
109 × Earth[9]
Surface area6.09×1012 km2[9]
12,000 × Earth[9]
Volume1.41×1018 km3[9]
1,300,000 × Earth
Mass1.9885×1030 kg[2]
333,000 × Earth[2]
Average density1.408 g/cm3[2][9][10]
0.255 × Earth[2][9]
Center density (modeled)162.2 g/cm3[2]
12.4 × Earth
Equatorial surface gravity274 m/s2[2]
28 × Earth[9]
Moment of inertia factor0.070[2] (estimate)
Escape velocity
(from the surface)
617.7 km/s[9]
55 × Earth[9]
TemperatureCenter (modeled): 1.57×107 K[2]
Photosphere (effective): 5,778 K[2]
Corona: ≈ 5×106 K
Luminosity (Lsol)3.828×1026 W[2]
≈ 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[11][12]
Rotation characteristics
(to the ecliptic)
(to the galactic plane)
Right ascension
of North pole[13]
19 h 4 min 30 s
of North pole
63° 52' North
Sidereal rotation period
(at equator)
25.05 d[2]
(at 16° latitude)25.38 d[2]
25 d 9 h 7 min 12 s[13]
(at poles)34.4 d[2]
Rotation velocity
(at equator)
7.189×103 km/h[9]
Photospheric composition (by mass)

The Sun looks yellow to a person standing on the Earth, but it is actually white. It looks yellow from the ground because the Earth's atmosphere scatters sunlight, causing shorter blue and green wavelengths to disperse, making the Sun's remaining visible light appear more yellow.

The Sun is a star like many others in our Milky Way galaxy. The Sun is a type of star called a G-type main-sequence star based on its spectral class.[15]

The Sun has existed for a little over 4.5 billion years.

The Sun is about a hundred times as wide as the Earth. It has a mass of 1.9891×1030 kg. This is 333,000 times the mass of the Earth. 1.3 million Earths can fit inside the Sun.[16] The Sun fuses about 600 million tons of hydrogen into helium every second.

The Sun is the main source of energy for the Earth. This energy is made deep inside the Sun in a process called nuclear fusion. Four hydrogen atoms are fused together to make one helium atom. Some of the leftover matter turns into energy. This is the same way energy is released in a hydrogen bomb.

It can take between 10,000 and 170,000 years for the energy in the core of the Sun to escape.