During the second half of the 19th century the French scientist and popularizer Camille Flammarion wrote many discourses on the subject of extraterrestrial life. His On the Plurality of Habitable Worlds was a much-read general treatment of the subject. Another work, entitled Imaginary Worlds and Real Worlds, was a review of all previous writings on the habitability of worlds and the possibility of interplanetary communication.45
In still another volume, Lands in the Sky, Flaminarion stated with conviction:
The Humanities of the heavens are no longer a myth. Already the telescope brings us in touch with their countries; already the spectroscope enables us to analyze the air they breathe…. From the bottom of our abyss we can visualize these far-away nations, these unknown cities, these extraterrestrial people!733
The publication of Darwin’s Origin of Species (1859) was soon followed by the development of an idea advanced by Swedish chemist Svante Arrhenius: Life may be ubiquitous thoughout the cosmos, carried from planet to planet by tiny space-spores (panspermia).1906
The modern era of scientific xenology was ushered in with Henderson’s important little book The Fitness of the Environment (1913), in which the Harvard biochemist attempted to demonstrate that both water and carbon are necessary in any living system on any planet in the universe.879 Superior astronomical data was becoming available, providing a still more accurate view of our solar system and galaxy.
The father of Russian astronautics, Konstantin E. Tsiolkovskii, wrote extensively on spaceflight and the possibility of ETs colonizing the Galaxy ahead of us. Alien civilizations, he pointed out, might well exist at many different levels of technological development;20 in 1925, Tsiolkovskii summarized by noting the distinct probability that “perfection and dominance of the mind” have been spreading throughout the cosmos.702
Fictional treatments of extraterrestrial life proliferated. During the late 19th and 20th centuries the use of aliens became a vehicle for both romantic and far-flung scientific speculative statement.
Achille Eyraud’s Voyage to Venus (1865) was the first fictional visit to that planet at a time when the idea of an inhabited Moon was virtually a dead letter.45 In another trip to Venus, Garret Putnam Serviss’s A Columbus of Space (1909), we find ape-like cave dwellers and beautiful telepathic humanoids.742 John Munro painted a most delightful picture of life on Venus in A Trip to Venus (1897);1872 Edgar Rice Burroughs also took us to Venus and Mars, as did C. S. Lewis in his well-known trilogy.364,348And Jupiter’s steaming jungles, replete with dinosaurs and pterodactyls, appeared in John Jacob Astor’s A Journey in Other Worlds (1894) — along with a brief excursion to Saturn.742
Voyages to other stars began to be written. With the French author Charles Ischir Defontenay we are transported to the star system of Psi Cassiopeia, in his 1854 novel of the same naine, for a quick dose of haunting space opera.564 David Lindsay’s A Voyage to Arcturus (1920) likewise is a romance, describing a visit to the extrasolar planet Tormance by spaceship and various adventures with the inhabitants there.1872
But it was certainly “Mars Fever” that inaugurated the present epoch of science in science fiction. In 1877, under unusual conditions of good seeing, the Italian astronomer Giovanni Schiaparelli observed what appeared to be “channels” crisscrossing the martian surface. Schiaparelli never maintained that his “channels” were relics of alien technology. Yet the word gained something in the translation into English: “Channels” became “canals,” with the connotation of intelligent engineering efforts.