"Moonbat" is a pejorative political epithet used in United States politics, referring to liberals, progressives, or leftists (especially the far-left).
[citation needed] Descriptions of bat-like people on the Moon were part of the 1835 Great Moon hoax.
A long poem, The Proving of Gennad: A Mythological Romance by Landred Lewis (1890), uses the term "moonbat" to refer to unsound ideas, but not specifically political ones.
[1] The term was used by science fiction author Robert A. Heinlein in the 1947 short story "Space Jockey" as the name of a rocket spacecraft used for the third step of a journey from the Earth to the Moon.
[2]