The Sun, also referred to as "Sol", is the star at the center of the Solar System. Sun’s mass accounts for some 99.86% of the total mass of the Solar System.


Roughly three-quarters of the Sun’s mass is hydrogen, with the rest mostly helium. Only 1.69% of the Sun (which is still 5 628 times the mass of the Earth) is made up of heavier elements like carbon, iron, neon and oxygen.


The mean distance of the Sun from the Earth is approximately 149.6 million kilometres (1 AU). On average, it takes light from the Sun about 8 minutes and 19 seconds to reach the Earth.


Once thought to be a relatively insignificant star, the Sun is now considered to be brighter than about 85% of the stars in the Milky Way galaxy. It is located about two thirds of the way out from the centre of the Milky Way.


Layer Composition
PhotosphereOpaque layer
Convective zoneHeat circles in thermal columns
Radiative zoneHeat radiates outward
CoreFusion reactions


The photosphere is a thin outermost layer of the Sun. Below photosphere, the Sun becomes opaque. However, the photosphere itself is only slightly less opaque than the air on Earth.

Convective zone

Thermal columns carry hot material to the surface of the Sun. Once the material cools off, it plunges back towards the hot radiative zone.

Radiative zone

The radiative zone carries the intense heat of the core outward as thermal radiation, with material rapidly cooling and the density of solar material decreasing a hundredfold from the top of the core to the top of the radiative zone.


99% of all power generated by the Sun comes from within 24% of the Sun’s radius.