Route de la Belle Etoile (Route of the Beautiful Star) documents the world of amateur astronomers across four continents. Over five years, photographer Daniel Stephen Homer traced a tangled web of collaborators who have made an outsized contribution to professional astronomical research, photographing amateurs and their observatories in the UK, France, Germany, Belgium, the Netherlands, India, Australia and Canada. His resulting photographs blend the domestic and the scientific, the mundane and the cosmic, taking the viewer on a journey into the world of astronomical citizen science. 'Many professional astronomers were once amateurs. The latter often leads to the former, but there is a gossamer thread between them: it's the subject of this book, a sort of grey zone of possibility where an amateur's reach can exceed their grasp.' Professional astronomers have never had the resources to chart the heavens completely alone, and amateurs have long filled in the cracks—tracking asteroids, discovering new celestial objects and sometimes working alongside professionals. The book features prolific citizen scientists alongside field notes detailing key astronomical discoveries and archival 'star glass' images: historical glass-plate negatives hand-annotated by women at Harvard College Observatory. The title is taken from a road in Grenoble, France, renamed at the request of an amateur spectroscopist.