From The Washington Post:
In 1877, the Italian astronomer Giovanni Schiaparelli was looking at Mars through his new telescope, and he noticed intricate etchings in the equatorial region of the planet’s surface. Schiaparelli called these lines canali, by which he probably meant something like “gullies” or “grooves,” but his coinage got wrongly translated into English as “canals.” It was a regrettable linguistic slip.The idea of Martian canals grabbed the imagination of American astronomer Percival Lowell, scion of the famous Boston Lowell clan, who spun out an elaborate story of a Martian civilization with a central planetary government and the technological wizardry to engineer a massive system of aqueducts. Lowell even used his own Arizona observatory to identify the Martian capital, called Solis Lacus.
There are no canals on Mars. No cities either, and no government. Indeed, no signs of past life whatsoever, as we know today. All of this was an elaborate phantasm of Lowell’s fertile mind, yet as late as the 1950s, popular culture was saturated with imagery of Martians as a technologically advanced extraterrestrial race. The late Carl Sagan used the misbegotten tale of Martian engineers, in his 1985 Gifford Lectures in Natural Theology at the University of Glasgow, as a cautionary tale about the power of belief and yearning to trump science and reason.
More here.