In this book a great deal of complicated material is skillfully handled and presented in comprehensible form; although the treatment is necessarily superficial, the author manages not to descend into didactic baby-talk. He surveys a number of evolutionary theories of the universe and its components: whether the universe evolved from an enormous explosion or whether there is constant autonomous creation of matters, why the retreating galaxies are shaped as they are; how stars are formed and why they don't burn out more quickly; how planets come to revolve about a sun, and whether there are other solar systems like our own with planets where intelligent life might have developed. He considers what our own Earth is like on the inside and out, how our changing relation with our Moon will sometime make our life on earth impossible; but how by that time the Sun will have cooled to such an extent that it will be too cold to live here anyway. Reassuringly, all of this is billions of years off. Meanwhile, other events may make life difficult: the polar ice-cap may grow and extend downwards into the now temperate zones just as it has before, and the Earth's crust, which once broke up to form continents with seas in-between, can't be counted on to stay put. This readable book is a model of its kind.