Donald E. Osterbrock is Professor Emeritus of Astrophysics at the University of California, Santa Cruz, and former Director of the Lick Observatory. He is the author or coauthor of Yerkes Observatory. 1892-1950: The Birth, Near Death, and Resurrection of a Scientific Research Institution: Pauper & Prince: Ritchey, Hale, & Big American Telescopes: Astrophysics of Gaseous Nebulae and Active Galactic Nucler, and Eye on the Sky: Lick Observatory's First Century. He coedited Origins and Extinctions

• PREFACE vii 1.The Preparation: Gottingen and Hamburg, 1893-1927 1 2.The Path toward the Two Populations: Hamburg, 1927-1931 25 3.Before the War: Mount Wilson, 1931-1938 49 4.War and a Great Discovery: Mount Wilson, 1939-1947 82 5.Young Stars and Old: Palomar and Princeton, 1948-1953 112 6.Radio Astronomy and the Size of the Universe: Palomar and Pasadena, 1948-1958 147 7.Telling the Good News: America and Europe, 1953-1959 177 8.The Finale and After: Australia and Gottingen, 1959-1960 200 ABBREVIATIONS 229 NOTES 233 BIBLIOGRAPHY 259 INDEX 261

"A delightfully engaging account of Baade's life and times, and a welcome addition to the history of 20th century astronomy. A fascinating account of Baade's life, accomplishments, and perhaps most interestingly, his times."--S. Alan Stern, Astronomy "Walter Baade was one of the key players in mid-20th Century astrophysics and this biography by Donald Osterbrock is welcome and timely... His story is a fascinating one, well told and nicely illustrated with contemporary photographs."--David Strickland, The Observatory "Baade was arguably the most influential observational astronomer of the 20th century... Donald Osterbrock ... meticulously documents Baade's life and work, with references to correspondence from more than 20 archives... He has focused on hitherto unknown or overlooked facts, shown why they are important, and created a new understanding. This is the essence of good history."--Norriss S. Hetherington, Physics Today "A gripping story told by an accomplished astronomer."--Neil English, Astronomy Now "A well-written and meticulously researched biography... It paints a picture of an innovative, hard working scientist who spent his whole life at the forefront of astronomical observation."--John Masters, Astronomy & Space