Five billion years ago, the universe had already existed for a long time. Countless stars had appeared, were exploded or extinct. The Milky Way already existed in our galaxie, and a huge cloud of gas, dust and rocks (a result from the explosion of stars) took the place of our solar system .
For reasons yet unknown, maybe due to the close explosion of a supernova, the solar nebula condensed, and its temperature rose considerably. 4.57 billion years ago, the sun shone for the first time. The planets needed another couple of million years to stabilize.
Among them was a large ball with a liquid surface which had until then gained only 2/3 of its future size: the Earth.