This book illustrates how the study of astrophysics requires training in several fields of physics, mathematics and technology. Based on the author's extensive teaching experience, it focuses on the basic observational data and theoretical methods used to build models for stars, galaxies and large-scale structures in the universe. Part I deals discusses gravitational theories, including basic general relativity and gravitational waves. In turn, Part II illustrates the radiation and plasma processes that are fundamental to interpreting the observed data and to modeling cosmic objects. Part III addresses the observational techniques needed in astrophysics, and the analysis of astrophysical parameters derived from photometry and spectroscopy. The book also includes an introduction outlining the historical development of the study of the universe, and a concluding chapter summarizing the physical properties of cosmic objects.

Attilio Ferrari was Professor Emeritus of Astronomy and Astrophysics at the Faculty of Sciences of the University of Torino, Italy until his passing in 2022.

Professor Ferrari served as Director of the Astronomical Observatory of Torino from 1986 to 2001. During this period, he was a member of the board of directors of the National Consortium of Astronomy and Astrophysics CNAA (1996-2001) and the Istituto Nazionale di Astrofisica - INAF (2000-3). Throughout his career, he contributed to numerous scientific boards. He served as President of the Inter-University Consortium for Space Sciences and also President of the Torino Museum of Astronomy and Space Science. In 2012, he was recognized with the Bruno Rossi Prize (High Energy Astrophysics Division, American Astronomical Society) as a member of the AGILE Team.

Professor Ferrari's research interests encompassed a broad spectrum, including theoretical models of the energetics and morphology of extragalactic radio sources and active galactic nuclei, numerical simulations of nonlinear hydrodynamical and magneto-hydrodynamical supersonic flows from active stars and galaxies and accretion disks, and high-energy plasmas in astrophysics and in fusion machines. He authored over 250 scientific papers in international journals and two textbooks.

1 Historical Outline.- 2 Newtonian gravitation.- 3 Relativistic theory of gravitation.- 4 Electromagnetic radiation mechanisms in astrophysics.- 5 Fluid processes.- 6 Plasma processes.- 7 Supra-thermal particle acceleration.- 8 Astronomical reference.- 9 Astronomical instruments.- 10 Elements of photometry and spectroscopy.- 11 Observable physical parameters of cosmic objects.