In this essay, Jan Golinski explores the careers of Adam Walker and his sons, who delivered public lectures on astronomy in London and the English provinces from the 1780s to the 1820s. Golinski traces the Walkers’ long-running success in the market for popular scientific lectures to their deployment of the “eidouranion,” or transparent orrery, and makes a suggestion about the design of this theatrical display apparatus. As the centerpiece of the Walkers’ shows, the eidouranion was complemented by a presentation that emphasized the aesthetic appeal of astronomy, especially in terms of the sublime. By conveying the majesty of the cosmos in their lectures, the Walkers elicited quasi-religious feelings of wonder and awe in their audiences. The rhetorical accomplishment secured the eidouranion’s place among the scientific spectacles of the Regency metropolis, and allowed the Walkers to discuss even the potentially controversial topic of the existence of life on other planets.