Abstract: How are intrinsic planetary magnetotails, leaky taps and certain types of coiled-spring systems related? Each system has a characteristic tension force which can be the source of oscillations. More specifically they can all be viewed as "relaxation oscillators" that exhibit different types of behaviour depending on system parameters. This seminar investigates the analogy between these different physical systems and discusses the observed types of behaviour of a model that qualitatively fits all of them, from the perspective of dynamical systems theory. The principle modes of behaviour are limit cycles and chaotic dynamics. These behaviours are defined and evidence for them in the model is presented. Implications for studies of planetary magnetotails are discussed. No background in dynamical systems theory or chaos theory is required.​