Part 1 Cosmography: what the universe contains; the cosmic distance hierarchy and the determination of galactic densities; parallax; distance from velocity measurements; distance from apparent luminosity; weighing galaxies; the red shift and the expansion of the universe. Part 2 Physical basis of general relativity: the need for relativistic ideas and a theory of gravitation; difficulties with Newtonian mechanics - gravity, inertial frames and absolute space; inadequacy of special relativity; Mach's principle and gravitational waves; Einstein's principle of equivalence. Part 3 Curved spacetime and the physical mathematics of general relativity: particle paths and the separation between events; geodesics; curved spaces; curvature and gravitation. Part 4 General relativity near massive objects: spacetime near an isolated mass; around the world with clocks; precession of the perihelion of Mercury; deflection of light; radar echoes from planets; black holes. Part 5 Cosmic kinematics: spacetime for the smoothed-out universe; red shifts and horizons; apparent luminosity; galactic densities and the darkness of the night sky; number counts. Part 6 Cosmic dynamics: gravitation and the cosmic fluid; histories of model universes; the steady state theory; cosmologies in which the strength of gravity varies. Part 7 In the beginning: cosmic black-body radiation; condensation of galaxies; ylem. Appendices: labelling astronomical objects; theorema egregium.