In the beginning, some 13.8 billion years ago, our universe was empty. Perhaps we can’t even say empty because there was no time, no space, no matter; there was nothing. Then came that wonderful moment we have titled The Big Bang, when there appeared the whole of our universe contained in a concentrated ball of energy smaller than an atom. That ball exploded outward in every direction. This explosion began as pure energy but quickly congealed to produce matter, and after some time (400k years), atoms appeared. Where these atoms were more densely compacted, the power of gravity increased and produced clouds of matter. As the density increased, temperature increased. When the temperature rose above 10 million degrees, protons fused, massive energy was released- boom, we have our first batch of stars.