Galaxies and Space: From the Milky Way to the Big Bang

Galaxies are not just clusters of stars, but key elements of the Universe’s large-scale structure. Understanding their properties, evolution, and distribution is essential to answer fundamental questions in cosmology: how the Universe formed, what it is made of, and what the future holds. This course provides a systematic introduction to modern cosmology and astrophysics, based on observational data and core physical principles. The program covers the classification of galaxies (spiral, elliptical, irregular) and their morphological features. You will study Hubble’s law — the linear relationship between a galaxy’s distance and its recession velocity — which laid the foundation for the idea of the Universe’s expansion. The course examines the cosmic microwave background in detail: its discovery, spectrum, anisotropy, and its role as a “snapshot” of the early Universe. Special attention is given to dark matter — its indirect signatures (galaxy rotation curves, gravitational lensing) and hypotheses about its nature. Key scenarios for the Universe’s future fate are also analyzed: the Big Crunch, heat death, and the Big Rip, using the density parameter and the cosmological constant. The course methodology is based on analyzing real astronomical observations and interpreting graphs (Hubble diagram, cosmic microwave background spectrum). You will learn to distinguish reliable experimental facts from theoretical models and avoid common misconceptions (for example, equating the Universe’s expansion with galaxies moving through space). Emphasis is placed on understanding the logical chain from observation to inference, rather than memorizing formulas. The course is intended for students in natural science fields (physics, astronomy), school and university teachers who want to update their knowledge in cosmology, as well as for science journalists and science communicators who need accurate terminology and a fact-based foundation. Upon completion, you will have a basic conceptual toolkit for cosmology: redshift, the age of the Universe, event horizon, and critical density. You will be able to explain how galaxy rotation curves are used to estimate the mass of a dark halo and interpret graphs of recession velocity versus distance. You will gain tools for further independent study of science popularization literature and astrophysics news.