In the preface to this book, Rhodri Evans describes cosmology as ‘understanding the beginning, evolution and nature of the Universe’. Probably every culture in human history has made a stab at doing this. What sets modern cosmology apart, however, is that it’s based on physical observations rather than metaphysical speculations. In a nutshell, that’s what this book is about – a chronological history of observational cosmology from the renaissance to the present day. The first chapter describes how careful observations by successive generations of astronomers gradually built up an accurate picture of the structure and scale of the solar system, followed by the extension of the cosmic distance scale to other stars in the Galaxy. The second chapter deals with the rapid progress made during the early decades of the 20th century in understanding the structure and dynamics of the Galaxy, the distances to other galaxies, and the expansion of the universe. A lot of the material in these fi