Early universe was mostly composed of hydrogen and some amount of helium the two lightest element found on earth. These elements are still most abundant in our universe. These elements are available in a huge quantity in intergalactic spaces. Due to gravitational pull sometimes these elements in their gaseous form creates huge cloud, often called as the inter-galactic cloud. As the cloud becomes denser it loses its opacity – means light from inside this cloud cannot easily diffuse out. These regions are where initial star formation starts taking place. Inside the star forming cloud, often called as “Protostar”, due to huge pressure of the gas column from above temperature starts to rise. At the same time gravity of the Protostar starts pulling more and more gas from cloud until the temperature becomes so high at the center that nuclear reaction starts taking place. Nuclear reaction uses the hydrogen gas as fuel and produce huge amount heat and light. Here is where our element cooking starts taking place. Once, a star starts burning the radiation emitted by it swipes away the cloud surrounding it. The star will now be visible from outside the cloud. It is worth to mention here that as the early universe was mostly composed of hydrogen and helium, the main composition of primitive stars were also the same. So the cooking was actually started with the lightest element. We will see in our next blog post how the heavier elements are produced.