9 billion years after the Big Bang
Around 9 billion years after Big Bang, our Sun formed from a huge cloud of gas and dust. It was mainly composed of hydrogen and helium, but with some “contamination” by the heavier elements created by the previous generations of stars.
As the Sun was forming, the gas and dust left over from the initial cloud was forming a disc around it. Over hundreds of millions of years planets grew out of the dusty disc, forming the Solar System we see around us today.
At the same time, the same thing was going on throughout the universe. We can even see it happening today within nebulae in our Universe. Just a few billion years after the formation of the Solar System, we evolved and built satellites such as Planck to explore the history of the Universe.