11) A System around a Star
The second generation of suns had a longer and richer life than their forebearers, but they too had their time. The deaths and supernovae of the second generation seeded their galaxies with heavier, more complex and interesting elements than there ever were before. The dust was like the nutrients in a good compost, because it meant good things could grow from it.A long time ago, in an outer spiral arm of the Milky Way, a vast cloud of dust collapsed and cascaded into its own centre. The matter squeezed together, heated up, and span into a disk. This happened in much the same way that the previous two generations of stars began their lives. The difference this time was that this spinning disk had a lot more material to work with. It spread and separated into rings which held a mixture of elements. Like a centrifuge, the heavier ones spread to edges, and the light gases stayed towards the centre. Parts of the rings began to clump together, into balls, rocks and boulders, sweeping up matter as they orbited.
The earth, and everything on it, formed out of a ring of this disk. The earth is made of stardust. We are made of stardust.