This module delves into stellar dynamics, revealing how gravity sculpts the behaviour and evolution of systems containing hundreds to billions of stars. You’ll learn how to describe and model the motion of stars within galaxies and clusters using classical mechanics, statistical methods, and dynamical theory. Key topics include gravitational potentials, orbital dynamics, the virial theorem, and the collisionless Boltzmann equation, alongside the physical processes that drive galactic evolution such as dynamical friction, phase mixing, and violent relaxation. By the end of the module, you’ll gain a deep understanding of how the collective motion of stars gives rise to the structure, stability, and long-term transformation of the galaxies we observe in the Universe.