Until Mariner 4 photographed craters on Mars in 1965, Earth-bound telescopes were the only way to map the red planet. BibliOdyssey looks at Schiaparelli’s 19th-century maps of Mars, which gave rise to the idea that canals — canali or channels in Italian — criscrossed the Martian surface. It was an optical illusion, but it was an idea that Percival Lowell took up as proof of intelligent life on Mars. (See also io9.)