The Star Diaries (Dzienniki gwiazdowe) by Stanislaw Lem, often published together with their sequel Memoirs of a Space Traveller, are supposedly the journals and travelogues of Ijon Tichy, a famous space traveller, recording his remarkable adventures exploring the cosmos. That, or a charlatan and liar, who makes a living off bamboozling gullible Earth-lubbers with astronautical folklore and hair-raising tall tales too absurd to be believed by anyone with so much as a grain of common sense. Take your pick.