In this essential, the author discusses astroparticle physics in a short historical outline and describes the latest results without going into mathematical detail. As an introduction to this new field of research, he gives an overview of what happens in the sky, between stars and between galaxies. By now, many things are quite well understood, but with every solution found, new questions arise - the author also deals with this spectrum of questions with some answers. Today, astroparticle physics is an active, interdisciplinary field of research that includes and combines astronomy, cosmic rays and elementary particle physics. This Springer essential translation of the original German was done with the help of artificial intelligence (machine translation by the service DeepL.com). A subsequent human revision was done primarily in terms of content, so that the book will read stylistically differently from a conventional translation. Springer Nature works continuously to further the development of tools for the production of books and on the related technologies to support the authors.