Mars, canals of

Apparent systems of straight-line markings on the surface of Mars, now known to be an illusion caused by the chance alignment of large craters and other surface features. Giovanni Virginio Schiaparelli (1835–1910) observed about 100 of what he described as channels. Percival Lowell called them canals and believed them to be evidence of intelligent life. Most astronomers could not see them, and many doubted their reality. The controversy was finally resolved only when pictures from Mariner spacecraft showed nothing resembling a network of channels.

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