From the dawn of human civilisations, Sun has played a crucial role in
the wonderland of the human mind. It has been perceived as a powerful
deity in the mythology of many civilisations because of its role in providing
the life on Earth. Today, we know that it is an ordinary star, which is centred at our solar system. It bears more than 99% mass of the solar system and holds all the planets in the solar system together
by its gravity.
The Sun has formed 4.5 billion years ago from the collapse of a giant, rotating cloud of gas and dust, called the solar nebula. It is a Population I star that is rich in heavy elements, and formed from the remnants of the supernova explosion of a previous giant star. It is primarily composed of hydrogen (73%) and helium (25%) with a negligible amount of heavier
elements such as oxygen, carbon, neon, silicon, magnesium and iron.
The Sun is a main-sequence star with a spectral class of G2V. It is located at a distance of 1.496× 108 km (1 AU) from the Earth and has a radius of 696,342 ± 65 km, which is about 109 times the radius
of the Earth. The mass of Sun is 1.9885 × 1030 kg, and its luminosity
is 3.86 × 1026 W. The solar spectrum can be approximated by blackbody
radiation with a temperature of 5785 K, that corresponds to the effective
surface temperature of the Sun .
The study of the Sun can be divided into two parts. The solar interior
that is composed of the core, the radiative zone and the convective
zone, and the solar atmosphere that includes the photosphere, the chromosphere,
the transition region and the corona. Solar interior is primarily divided into three main regions based on energy
generation and transfer processes. They are - the core, the radiative &
the convective zone.
