Among Schiaparelli's contributions are his telescopic observations of
Mars. In his initial observations, he named the "
seas" and "continents" of Mars. During the planet's "great
opposition" of 1877, he observed a dense network of linear structures on the surface of Mars, which he called in Italian, meaning "channels", but the term was mistranslated into English as "canals". While the term "canals" indicates an artificial construction, the term "channels"
connotes that the observed features were natural configurations of the planetary surface. From the incorrect translation into the term "canals", various assumptions were made about life on Mars; as these assumptions were popularized, the "canals" of Mars became famous, giving rise to waves of hypotheses, speculation, and
folklore about the possibility of
Martians, intelligent life living on Mars. Among the most fervent supporters of the artificial-canal hypothesis was the American astronomer
Percival Lowell, who spent much of his life trying to prove the existence of intelligent life on the red planet. After Lowell's death in 1916, astronomers developed a consensus against the canal hypothesis, but the popular concept of Martian canals excavated by intelligent Martians remained in the public mind for the first half of the 20th century and inspired a corpus of works of classic
science fiction. Later, with notable thanks to the observations of the Italian astronomer
Vincenzo Cerulli, scientists came to the conclusion that the famous channels were actually mere
optical illusions. The last popular speculations about canals were finally put to rest during the spaceflight era beginning in the 1960s, when visiting spacecraft such as
Mariner 4 photographed the surface with much higher resolution than Earth-based telescopes, confirming that there are no structures resembling "canals". In his book
Life on Mars, Schiaparelli wrote: "Rather than true channels in a form familiar to us, we must imagine depressions in the soil that are not very deep, extended in a straight direction for thousands of miles, over a width of 100, 200 kilometres and maybe more. I have already pointed out that, in the absence of rain on Mars, these channels are probably the main mechanism by which the water (and with it organic life) can spread on the dry surface of the planet." == Martian nomenclature ==