This book relates an attempt to decrypt the still-obscure first billion years of history of the young Earth, during a cataclysmic period during which our planet was heavily bombarded by bodies ranging in size from that of Mars to 0.1 mm sized tiny micrometeorites. It was thus found that micrometeorites played an essential role in the formation of the post-lunar atmosphere. They also provided a surprisingly large diversity of reactions in the organic prebiotic chemistry required for the birth of life on our blue planet. The author presents a wide-ranging review of the type of knowledge required to decrypt this history, which provides extensive background information from astronomy, planetary dynamics, planetology, astrobiology and earth sciences. This book will appeal to both the scientist and the general reader. It will be a source of material for lectures, and possibly new investigations, in these fields.