The spectacular reappearance of the aurora borealis at the beginning of the 18th century, often observed simultaneously from different observatories in Europe, mobilized and federated a large community of astronomers on a European scale. It encouraged them to communicate the results of their observations and, in compiling exhaustive catalogs of information, has helped to establish a system of the aurora borealis that can be further studied in the future, according to the experimental method inherited from the previous century. This book is dedicated to some of the main aurora observers in Europe and to the human, institutional and philosophical context in which they evolved in the first half of the 18th century. Its reading should be seen as a retrospective journey through the scholarly world of the Enlightenment, during which the same scholars are frequently encountered and reencountered, yet each time in different contexts, or from different angles, with the aim of compiling an account of the swarming of ideas and encounters that constituted the development of experimental science in this pivotal period.