This book provides a concise, non-mathematical summary of key astronomical discoveries, organized chronologically from the founding of the International Astronomical Union in 1919 to the present day. It highlights significant findings related to solar and space physics, exoplanets, astrophysics and cosmology.Focusing on the 20th century, this volume offers a comprehensive overview of major breakthroughs in heliophysics, planetary exploration, the study of the interstellar medium, and the recent discovery of exoplanets. Additionally, it gives an account of the exploration of pulsars, white dwarfs, and neutron stars, alongside developments in high-energy astrophysics, such as the study of supernovae, active galactic nuclei, extragalactic jets, quasars, black holes, and X- and γ-ray astronomy. Further, the book discusses discoveries in galactic hierarchy and the cosmic voids, the bubbles of the cosmic web as well as the discovery of gravitational waves and multi-messenger astronomy. It also explores the investigations into the early Universe, dark matter, and dark energy.This work serves as a valuable resource for students, educators, researchers, and the general public, offering insights into how these groundbreaking discoveries have shaped our understanding of both the nearby and the distant Universe over the last century and into the present day.
