What constitutes a scientific discovery? What role do discoveries play in science, its dynamics and social practices? The paper explores these questions by first critically examining extant philosophical explications of scientific discovery—the models of scientific discovery, propounded by Kuhn, McArthur, Hudson, and Schindler. As an alternative, we proffer the “change-driver model”. In a nutshell, it conceives of discoveries as problems or solutions to problems that have epistemically advanced science. Here we take a problem to be generated by a datum that (...) we want to account for and make sense of—by putting it in contact with our wider web of scientific knowledge and understanding. The model overcomes the shortcomings of its precursors, whilst preserving their insights. We demonstrate its intensional and extensional superiority, especially with respect to the link between scientific discoveries and the dynamics of science, as well as with respect to its reward system. Both as an illustration, and as an application to a recent scientific and political controversy, we apply the considered models of discovery to one of the most momentous discoveries of science: the expansion of the universe. We oppose the 2018 proposal of the International Astronomical Union as too simplistic vis-à-vis the historical complexity of the episode, and as problematically reticent about the underlying—and in fact crucial—philosophical-conceptual presuppositions regarding the notion of a discovery. The change-driver model yields a more nuanced and circumspect verdict: (i) The redshift-distance relation shouldn’t be named the “Hubble-Lemaître Law”, but “Slipher-Hubble-Humason Law”; (ii) Its interpretation in terms of an expanding universe, however, Lemaître ought to be given credit for; (iii) The Big Bang Model, establishing the expansion of the universe as an evidentially fully warranted result in the 1950s or 1960s (and a communal achievement, rather than an individually attributable one), doesn’t qualify as a discovery itself, but was inaugurated by, and in turn itself led to, several discoveries. (shrink)