NUCLEAR FUSION REACTION IN SUN

Sun is a yellow dwarf star located at 27000 light-years away from the center of the Milky Way galaxy in the Orion Cygnus arm. The Sun and the entire Solar System was formed from the gravitational collapse of the Solar Nebula 4.5 billion years ago. Sun comprises 99.8% of the total mass of the Solar System. The Sun is the heat source of the entire Solar System. The Sun is a gas giant mainly comprising of two major elements; hydrogen which occupies 70% and helium which occupies 27.4% of a total solar mass. The elements inside the Sun are held together by immense gravitational force and thereby producing a high amount of pressure and temperature and creating adequate conditions for the nuclear fusion reaction to occur. Our Sun is classified into six regions called the Core, the Radiative zone, the Convective zone, the Photosphere, the Chromosphere, and the Corona. The Core of the Sun has a whopping 27 million degrees Fahrenheit. Inside the core, nuclear fusion reaction takes place by fusing two hydrogen atoms into helium thereby releasing enormous amounts of energy in the process. There are two types of fusion reactions in the stars. The Proton-Proton cycle occurs in Sun-like stars and the Carbon-Nitrogen-Oxygen cycle that occurs in massive stars. In the Proton-Proton cycle, two protons which is positively charged hydrogen atoms coalesce and form one Deuteron, one Positron and one Neutrino. Positron annihilates with free electrons releasing greater amounts of energy in the form of Gamma rays. The Deuteron then collides with one proton creating a helium-3 nucleus. Two helium-3 nuclei then combine and form a stable helium-4 nucleus and 2 protons releasing tremendous amounts of energy in the form of radiation. This radiation travels through the Radiative zone to the Convective zone. It takes 170000 years for the formed radiation to travel from core to the Convective zone. The temperature at the convective zone is around 3-3.5 million degrees Fahrenheit. From here, the hot plasma of ionized radiation travels upward to the Photosphere. Here most of the radiation escape into the heliosphere and it takes eight minutes for the solar radiation to reach Earth. Solar radiations are basically electromagnetic radiation. Ultraviolet rays, Visible light, and Shortwave Infrared rays are the forms of electromagnetic radiation emitted by the Sun. UV rays reaching the Earth is reflected off by the Ozone protective layer shielding the Earth. Some of the infrared rays are reflected off into outer space while some is absorbed by the atmospheric gases like carbon dioxide to keep the Earth warm. Visible light is all the light that can be seen from the naked eye that is emitted by the Sun.