Martin Harwit is Professor Emeritus of Astronomy at Cornell University, New York. For many years he also served as Director of the National Air and Space Museum in Washington, DC. For much of his astrophysical career he built instruments and made pioneering observations in infrared astronomy. His advanced textbook, Astrophysical Concepts (1973), has taught several generations of astronomers through its four editions. Harwit has had an abiding interest in questions first raised in Cosmic Discovery on how science advances or is constrained by factors beyond the control of scientists. His subsequent book, In Search of the True Universe (Cambridge, 2014), explores how philosophical outlook, historical precedents, industrial progress, economic factors, and national priorities have affected our understanding of the cosmos. This new book rounds out his informal trilogy on the themes of cosmic discovery. Harwit is a recipient of the Astronomical Society of the Pacific's highest honor, the Bruce Medal, which commends 'his original ideas, scholarship, and thoughtful advocacy'.

Preface; Part I. Instruments, Messengers, and Cosmic Messages: 1. Instruments, Messengers, Astrophysics and Cosmochemistry; 2. Primordial Messengers and their Interpretation; Part II. The Bounded Energies of Nature's Messengers: 3. Cosmic Ray Particles, Photons, and Leptons; 4. Gravitational Waves; 5. Gravitational Lensing; Part III. Parameters Specifying Individual Messengers: 6. The Ranges of Messenger Parameters; Part IV The Pace of Progress; 7. An Era of Surveys; 8. The Accumulation of Discoverable Phenomena; 9. The Human Aspect of the Cosmic Search; Appendix: Symbols, Glossary, Units and their Ranges; Index.