GK Chronicle GK Chronicle

World Geography / Universe and Solar System

External and Internal Structure of the Sun


    The internal structure of the Sun is having 3 parts, namely Core, Radiative Zone and Convection Zone whereas the external structure comprises of Sun's atmosphere. Sun is made up of 75% Hydrogen, 24% Helium and 1% other elements. Around 70 elements are common to both Earth and the Sun.

    Internal Structure of the Sun

    • Of the three parts of the internal structure of the Sun, Core is the innermost part. It is the most densest part ( having specific gravity of 100 ) and accounts for 1/3rd mass of the Sun. In core, thermonuclear reactions take place. Average temperature of core is around 15 million0C.

    • The layer next to Core is Radiative zone ( having specific gravity of 1 ). It accounts for another 1/3rd mass of the Sun. This layer allows radiation to go out. Temperature of Radiative zone is 2.5 million 0C.

    • The layer next to Radiative zone is Convective zone ( having specific gravity of 0.1 ). It is made up of opaque gases. This layer generally tries not to allow the heat energy to go out. The temperature of Convective zone is 1.1 million 0C.

    External Structure of the Sun

    • The atmosphere of Sun has 3 layers, Photosphere, Chromosphere and Corona.

    • When the heat energy reaches to the end of the convection zone, it cools by giving light. The region where this light emerges is Photosphere. Photosphere is an extremely thin layer ( having specific gravity 1/(1 million) to 1/(10 million) ). The temperature of Photosphere is about 50000C. It is the visible yellow surface of sun.

    • The layer of Sun's atmosphere above the Photosphere is known as Chromosphere. The temperature rises as we move outward and it reaches up to about 20,0000C at the top of the Chromosphere.

    • The topmost part of the solar atmosphere is Corona. Corona is visible at the time of total solar eclipse. The temperature in Corona is higher than that of Chromosphere and it has an average temperature of 1 to 2 million 0C.

    • Sunspots can be found on the surface of the Sun. These are relatively cooler and darker regions. Sunspots occur in cyclic manner and the cycle duration is generally 11 years. Intensity of solar radiation is more when there is maximum number of sunspots. Its impact can be found on the earth and it disturbs our terrestrial communication as well.