Martian canals, 1884.

UNITED KINGDOM - FEBRUARY 06: Plate from 'Les Terres du Ciel' (The Worlds of the Sky) written by the French astronomer Camille Flammarion (1842-1925). The plate is an artist's impression of how canals on Mars might have looked. The idea that there might be canals on Mars originated with the Italian astronomer Giovanni Schiaparelli, who claimed to have observed features he described as canali (channels) in 1877. Flammarion was not the only supporter of the idea; the respected American astronomer Percival Lowell (1855-1916) theorised that a civilization, faced with climate change, had built the canals to transport water from the planet�s ice caps to irrigate crops. In fact the canals did not exist; they are now thought to have been optical illusions possibly caused by dust storms. (Photo by SSPL/Getty Images)