life on the Moon
Map of the Moon by Hevelius.
Among ancient philosophers to speculate about possible lunar inhabitants were Anaxagoras, Xenophanes, Pythagoras and his followers, Plutarch, and (in fiction) Lucian. In the late middle ages, Nicholas of Cusa favored life on the Moon. However, speculation became more intense following the Copernican Revolution and Galileo's first lunar studies with the aid of a telescope (1608). In his Discovery of a New World in the Moone (1638), John Wilkins summarized what were then widely held beliefs:
That those spots and brighter parts which by our sight might be distinguished in the Moon, do show the difference between the Sea and Land of that other World... The spots represent the Sea, and the brighter parts Land... That there are high mountains, deep valleys, and spacious plains in the body of the Moon... That there is an atmosphere, or an orb of gross vaporous air, immediately encompassing the body of the Moon... That it is probable there may be inhabitants in this other World, but of what kind they are is uncertain...
Even at this early stage, however, there was sharp disagreement over how to interpret what the telescope showed. The two great lunar map-makers of the seventeenth century, Johannes Hevelius and Giovanni Riccioli, stood at opposite poles of the debate. Whereas Hevelius populated his chart with seas and "selenites" (as he called his lunar inhabitants), Riccioli's Moon was dry and dead. The battle over lunar life continued throughout the 18th century, Johann Bode and William Herschel being notable among the pro-selenites.
By the turn of the nineteenth century, persuasive evidence was accumulating that the Moon lacked both sufficient air and water (see Moon, water on) to support substantial life. Yet still the selenites had their champions, including the extremists Schröter and Gruithuisen, and the moderates Gauss, von Littrow, and Olbers. Improved lunar maps in the 1830s, by Wilhelm Lohrmann and by Beer and Mädler, helped persuade most astronomers that the Moon was unlikely to be inhabited. Even so, this did not prevent Richard Locke from creating a worldwide sensation in 1835 with his great "Moon Hoax".
By the end of the nineteenth century, lunar life had passed more or less from the realm of science into that of science fiction. Jules Verne posed the question in Around the Moon (1870) and teased with his reply, George Griffith's adventurers in Stories of Other Worlds (1900) find the ruins of a civilization and its bestial offspring, while, as late as 1901, in The First Men in the Moon, H. G. Wells was able to exploit lingering public credulity with his tale of a hollow Moon, richly varied selenites, and massively cerebral Grand Lunar (see Moon, voyages to).
And yet the romance did not quite end with these gaslight fantasies. In the 1920s, William H. Pickering, a staunch advocate of Martian vegetation (see Mars, life on) argued that certain dark areas on the Moon which changed shape were due to spreading plants,1 while almost half a century later the remote possibility of microbial lunar life was still on the minds of NASA scientists when they quarantined the first Apollo astronauts and their rock samples (see back-contamination) – a well-advised (but, in the event, ill-performed) precaution in view of the bacterial survivors found on the returned camera of Surveyor 3. Arthur C. Clarke suggested remains of another kind on the Moon in his short story "The Sentinel"2 which blossomed into 2001: A Space Odyssey.
In reality, it seems, the Moon has always been dead. However, the prospects for future intelligent (human) life on our nearest neighbor have been greatly improved by the discovery of billions of tons of ice in some deep lunar craters (see Lunar Prospector).
1. Pickering, W. H. "Eratosthenes," 1 to 6, Popular Astronomy,
nos. 269, 287, 312, and 317 (1919-25).
2. Clarke, Arthur C. "The Sentinel." In Expedition to Earth. New York: Harcourt, Brace and World (1970).