Source : Google

Stars are the fixed luminous bodies in space. They are one of the major sources of all the light there is in the universe. The observable universe has a humungous number of stars and galaxies which includes at least 1 to 2 trillion galaxies in the observable universe out of which one is our own galaxy, i.e. Milky Way which itself packs approximately 100 thousand million stars making one fact very clear that — The observable universe has many many many stars.


We are now aware of the fact that there are trillions and trillions of stars in our entire universe, but how did so many stars actually come into existence? Did they just show up or did they go through a complete process? Well, they did go through a process that resulted in the birth of a single star.

Post 20 minutes of the Big Bang, the universe witnessed the formation of atoms of Hydrogen and Helium, which were indeed the very first elements in existence at that time. These gases, over the period of time (millions of years), started to accumulate into giant clouds of gases known as a Nebula which, on average, had a width just more than a lightyear (1 lightyear = 9.46 x 10¹² km). Gases, in general, exert an outwards force, that is, gas molecules get pushed outwards. Similar phenomena happens with the gas clouds and it experiences an outward push. But, as the gas clouds are also made up of matter, it exerts an inward force pulling the gas cloud inwards. Thus, both the forces simply cancel out and the gas cloud attains a state of equilibrium (It is a state where the physical state of a body does not change).

Even though the Nebula is in a state of equilibrium, it still collects mass from its surroundings by accumulating more Hydrogen and Helium atoms until it crosses a limit known as Jeans Mass (Jeans mass is a fixed amount of mass which when crossed forces to the body to collapse under its own gravity). In this scenario, after the Nebula crosses its Jeans mass, its gravitational force overrides the outward pressure exerted by the cloud and forces it to collapse.

Due to the nuclear fusion, that takes place in the core, a tremendous amount of energy is generated. This energy now pushes against the force of gravity, cancelling out its effects which put the gas cloud in a stable state. The process is now complete, and a star is born.

Image of a nebula. Source : Google

Such beautiful phenomena are taking place even right now as you are reading this blog. We, as humans, miss out a lot of such events just because of our limitations but let us hope that someday there is going to be a time when we will not have anything or any particular barriers stopping us from witnessing such beauties. At the end, I would like to end this read with one of the best words by Stephen Hawking…
Be curious…

A physics lover forever and ever… Come witness the beauty of the universe once and forever be in love of it and bow down to its grand design.