There are many candidates. An article from the web site Brainpickings proposes the great innovator in astronomy and mathematics Johannes Kepler. He wrote his thought-experiment, Somnium, or The Dream, in 1608, but not until four years after his death was it finally published (in 1634 by Kepler’s son). The tale imagines a young astronomer traveling to the moon. Read it, and all about it, here. Recently, readers of interesting fiction may have encountered Kepler through Riva Galchen’s amazing historical novel (2021), Everyone Knows Your Mother is a Witch. She based it on actual historical documents, but she brings this account of Kepler’s mother’s witch trial alive through grim and hilarious imaginings and wonderful writing. The novel gives readers some great insights into the controversies and religious bigotry of the times, which Kepler as well as his mother had to battle their entire lives.