Our story begins with the formation of our Earth about 4.55 billion years ago from the swirling disk of dust and gas, at the centre of which was the young Sun. The latter was formed from the large concentration of material in the middle of this disk. Other concentrations had begun to emerge outside the centre and these grew with time, attracting increasing amounts of material by their growing gravity. The more matter gathered in these concentrations the greater the gravity they had, this in turn causing some of them to steadily increase in size. These concentrations yielded the eight planets we know in our Solar System, with many smaller fragments forming asteroids in the region between Mars and Jupiter and other objects, far beyond the planets, in the Kuiper Belt and the even more distant Oort Cloud.