Although some of the observational and conceptual roots of modern cosmology can be traced back to the nineteenth century, it was only in the twentieth century that the study of the universe as a whole emerged as a genuine physical science. The development through the twentieth and now well into the twenty-first century has been far from smooth, but in spite of a number of false trails it has been tremendously fruitful and surprisingly successful scientifically. The volume presents a comprehensive overview of the development of cosmology from about 1860 to the most recent discoveries. It describes and explains the historical background to what we know about the universe today and what people in the past thought they knew about the universe, starting with the first observations of spiral nebulae and ending with the discovery of gravitational waves. The book is organized into thirteen roughly chronologically ordered chapters, some focusing on theory and others more on observations and technological advances. A few of the chapters are of a more general nature, relating to larger contexts such as politics, philosophy and religious world views. The chapters are written by eight different authors, some of whom are astrophysicists or cosmologists while others have backgrounds in the history and philosophy of science. Each chapter can be read separately but also has a symbiotic relation with the other chapters. As a result, the book describes the history of modern cosmology coherently, comprehensively and with ample references to the relevant sources. Helge Kragh gained doctoral degrees in physics (1981) and in philosophy (2007). He was a high school teacher in physics and chemistry (1970-87), and then later a professor of history of science at Cornell University, USA; University of Oslo, Norway; and University of Aarhus, Denmark (1987-2015). After retiring, he is now emeritus professor at the Niels Bohr Institute, University of Copenhagen, Denmark.

Malcolm Longair is Director of Development and Outreach, Jacksonian Professor Emeritus of Natural Philosophy at the Cavendish Laboratory, University of Cambridge, UK. He also holds the position of Editor-in-Chief of the Biographical Memoirs of Fellows of the Royal Society (2016-2020). Longair has previously held positions as a university lecturer in the Department of Physics, University of Cambridge (1970--80); Astronomer Royal for Scotland, Regius Professor of Astronomy, University of Edinburgh, Director of the Royal Observatory, Edinburgh (1980-90); Jacksonian Professor of Natural Philosophy, University of Cambridge (1991-2008); and Head of Cavendish Laboratory (1997-2005).