Advances in observational techniques have produced a wealth of data and unexpected discoveries which have helped to reshape astrophysics as a field with well-formulated theories and sophisticated numerical calculations. In nuclear particle physics, plasma physics, as well as in general relativity, the universe has become a laboratory for research. The courses collected in the book are intended to provide students with this insight, giving a general background on each topic such as cosmic rays, nuclear and neutrino astrophysics, solar physics and strong fields, as well as a presentation of the current research and open problems. The book is aimed at graduate students in physics and astrophysics, as well as researchers, bridging a gap between the specialized reviews and the comprehensive books.