This book is organized by physical subjects, such as planetary surfaces, planetary interiors and atmosphere. Only this approach allows true comparative planetology (i.e., presentation of general physical principles, such as volcanism, tectonic evolution, mantle convection, cratering processes, and atmosphere temperature structure, followed by applications to various individual planets, satellites and interplanetary bodies). It is aimed at a short course in planetary science which covers planetary surfaces and interiors, atmosphere, origin of the solar system, and small bodies such as asteroids, comets and meteoroids.