The book is the product of efforts to collect, process, and edit university exercises in Astronomy-Astrophysics that were taught in the Physics Department at Aristotle University of Thessaloniki in previous years and includes - in terms of exercises - the entirety of the sections of the corresponding course of the 5th semester of the relevant department's curriculum.

The purpose of this project is to provide assistance that may potentially help students of Physics (and related departments) and any interested reader regarding the interpretation and understanding of astronomical-astrophysical phenomena.

The book is divided into chapters-sections based on the university textbook by H. Barvoglou and I. Ch. Seiradakis "Introduction to Modern Astronomy," while the material of Astrophysics is primarily covered by Frank H. Shu's book "Astrophysics. Structure and Evolution of the Universe" (I and II).

Sincere thanks to our dear professors in the Astronomy-Astrophysics department Charalampos Barvoglou, Ioannis-Chiou Seiradakis (who unfortunately is no longer with us), Stavros Avgoloupis, and Loukas Vlachos, who as instructors are behind this project, as well as to the younger colleagues Dimitris Sapalidis, Lazaros Pelekas, and Nikos Koutsopoulos, who thoroughly reviewed the original text.