Question: How were stars formed?

Hussain Jaffery answered on 14 Nov 2015:

The first stars were formed in the early universe and most of them have probably died off, and given birth to new stars. How does this happen?

Stars are composed of mainly hydrogen – the first element in the periodic table and composed of just one proton. Stars join two hydrogen atoms together in a reaction called nuclear fusion, which gives off that brilliant light and other kinds of radiation. In the early universe, 13.8 billion years ago, after the Big Bang and the rapid expansion of the universe, there was a lot of hydrogen that formed, from the energy of the Big Bang. As the universe kept expanding, it started to slightly cool. This allowed the the newly formed hydrogen gas to start collecting together – caused my the force of gravity. Gravity pulls everything that mass together.

Clouds of hydrogen gas start to combine into balls, which get bigger and bigger as they collect more hydrogen, then they start getting hot, because of the heat from all of the hydrogen atoms rubbing together and squeezing each other. This started the first fusion reactions. If you were to look at the universe at this time, you would see small specks lighting up here and there – the first stars. These stars would have only been ‘babies’ and would have looked a lot like spinning clouds or hurricanes – with the inner hot core and outer arms of gas.

Over time, they matured in to the clean rounded stars. And many have died since. Our own star, the Sun has come from the explosions of old stars that died out. The gas and dust which the old stars left behind in the explosions eventually collected together again, because of gravity, and once again a star could form from the same process above! 🙂