What did the ancient Greeks and Romans think about the possibility of life on other worlds? What would extra-terrestrial life-forms look like? What would they eat, and how would they reproduce? What would the climate of their world be like – and why? And how can we speculate, reasonably, about the nature of other worlds, when we cannot visit these worlds ourselves?

It is not widely known that such questions, which underlie the modern science of astrobiology, also concerned philosophical, scientific and imaginative thinkers throughout Greek and Roman antiquity, as far back as the fifth century BC. In antiquity, these debates focused on the Moon, which was widely considered to be an inhabited world. This presentation will introduce some of the principal theories in ancient astrobiological thought, and explore how the ancient Moonmen represented a sophisticated combination of philosophical and scientific thinking.