Welcome to the planet earth. A place of blue nitrogen skies, oceans of liquid water, cool forests, soft meadows; A world positively rippling with life. From the cosmic perspective, it is, for the moment, unique. The only world on which we know with certainty that the matter of the cosmos has become alive, and aware. There must be many such worlds scattered through space, but our search for them begins here, with the accumulated wisdom of the men and women of our species, acquired at great cost, over a million years.