The very first sci fi, written at the height of people making stuff up and prtending it was history (looking at you, Herodotus). Nice to see the art of the spoof is so old...

From the wiki:

A True Story (Ancient Greek: Ἀληθῆ διηγήματα, Alēthē diēgēmata; Latin: Vera Historia or Latin: Verae Historiae), also translated as True History, is a long novella or short novel written in the second century AD by the Syrian author Lucian of Samosata. The novel is a satire of outlandish tales that had been reported in ancient sources, particularly those that presented fantastic or mythical events as if they were true. It is Lucian's best-known work.

It is the earliest known work of fiction to include travel to outer space, alien lifeforms, and interplanetary warfare. It has been described as "the first known text that could be called science fiction". However, the work does not fit into typical literary genres: its multilayered plot and its characters have been interpreted as belonging to science fiction, fantasy, satire or parody, and have been the subjects of scholarly debate.