Does one planet really matter among the immensity of the Cosmos? John Gribbin is here to persuade us that it does. In this ground-breaking and provocative new book Gribbin argues that we owe our existence to the impact of a 'supercomet' with Venus 600 million years ago. But this is only part of the story, just one of the astronomical and geophysical reasons why the Earth is special. For the first time, he makes the link between the whole series of cosmic events that have affected the Earth and given rise to our intelligent civilization - a civilization, Gribbin argues, that is unique within our Milky Way Galaxy. Even if other Earths are common, and life itself may be common, the kind of intelligent, technological civilization that has emerged on Earth occurs only here. If humankind can survive the present environmental crises, the whole of the galaxy may become our home. And if not, our demise may be an event of literally universal significance.