Introduction with Sun
Sun is a star present at the center of our solar system around which all our eight planets of our solar system revolve.It is nearly perfect sphere of hot plasma, which provides energy for life on Earth.
The diameter of Sun is about 1.39 million kilometers which is around 109 times the diameter of Earth and has mass about 3,30,000 times that of Earth, which constitutes about 99.86% of the total mass of our solar system.The temperature of the visible part of Sun is about 5500 degree celsius while the temperature of core is about 15 million degree celsius.
Sun orbits around the center of Milky Way galaxy from a distance of about 25,000 light years and takes around 250 million years to complete its one rotation.
Formation and Evolution of Sun
The Sun was formed about 4.6 billion years ago (means current age of our Sun is 4.6 billion year). How the formation of this star takes place, indeed an interesting question.
According to Scientists, the Sun and rest of our solar system formed from a giant, rotating cloud containing gases(like hydrogen and helium) and dust known as solar nebula.Something like that:-
Credit:-NASA; Source: (https://www.nasa.gov/mission_pages/spitzer/multimedia/spitzer-20090513anim.htmlv)
With the passage of time, the gases and dust inside the cloud started collapsing with each other due to high gravity. The collapsed gases and dust then leads to the formation of disk like structure, which started to spun faster. As result of which some of its mass was pushed towards the center, resulting in the formation of Sun and rest of mass give rise to our planets and rest of our solar system.
Composition of our Sun
Sun mainly consists of chemical elements like hydrogen and helium .The composition of hydrogen is about 74.9% , whereas helium has a composition around 23.8% ; rest 2% of total percentage consists of heavy elements like oxygen(1%), carbon (0.3%), Neon(0.2%) and iron (0.2%). Hydrogen and helium in the Sun was produced by Big Bang Nucleosynthesis while heavy elements were introduced from previous generations of star before the Sun was formed.
According to a study; for every 1 million atoms of hydrogen in Sun, there are 98,000 of helium, 850 of oxygen, 360 of carbon, 120 of neon, 35 of iron and rest of other elements like silicon, nitrogen and magnesium.
Source of Sun's energy
From its birth, Sun is releasing energy to all solar system in form of heat and light which helps Earth to maintain life on it.But the main question here is that how Sun produces so much energy?? So the short answer is nuclear fusion - the process in which hydrogen on Sun gets converted into helium.The specific type of fusion that occurs inside the Sun is proton-proton fusion.
In proton-proton fusion two protons(hydrogen ions) after undergoing a series of steps, fuse together to form helium with release of large amount of heat and light energy, which make Sun and other solar system hot and bright.The basic chain of reaction is as shown below:-
Img source:(https://en.wikipedia.org/wiki/Proton%E2%80%93proton_chain_reaction)
The various steps involved during the reaction are as follows:-
In first step, two protons (hydrogen ions) break down to form a neutrino and a positron, along with the formation of neutron. The neutron combines with proton to form Deuterium isotope of hydrogen.
In second step, deuterium collides with another proton, resulting in the formation of helium-3 nuclei and gamma rays, which are released as sunlight.
Then two helium-3 nuclei collide with each other, creating a helium-4 nucleus .
As the final helium-4 has less mass as compared to first 4-protons, there is release of energy according to Einstein's equation:-
This reaction continues, hence we get continues release of heat and light energy.
Citations:-
(https://www.space.com/58-the-sun-formation-facts-and-characteristics.html)
(https://energyeducation.ca/encyclopedia/Nuclear_fusion_in_the_Sun)
