Since Kepler’s Somnium, the imagination of other planets has played a decisive role in the controversy over the inhabited galaxy; in this respect cosmographic phantasy, i.e. the “extraterrestrial experience”, supports the astronomical argument. Even so, however, how does cosmographic phantasy explain itself? Although the epistemological principles of the conditio extraterrestris have already been investigated satisfactorily, the evolution of the poetic concepts that assist the meaningful representation of the extraterrestrial space still remains untold. To shed light on them is of great scientific relevance, not least because from its inception, extraterrestrial imagination receives its images from a network of information that is, in turn, managed by the spirits of outer planets. The phantasy of the universe, stellar knowledge and stellar beings are closely related to each other from the very start. The historical transformations of this alliance – i.e. the semantic reshuffle of planetary worlds, the gradual emancipation of the universe and its inhabitants from early modern systems of knowledge, the reprocessing of ‘astronomical revolutions’ by literary phantasy — define the research area of the present study. The project follows cosmographic narration from its beginnings until well into 20th century Science Fiction by finding the path that goes from axiomatic learned fiction to cosmological interpretation, from the flood of popular scientific images to the literary expeditions into the infinite All. In this way, the project fulfils its aim and sheds light on the spatial narrative principles of the conditio extraterrestris.