Some early observers, limited by their instruments — and perhaps seeing what they wanted to see — came to spectacular conclusions.
Italian astronomer Giovanni Schiaparelli mapped what he believed were straight lines on the surface of Mars in 1877. He called them "canali," meaning channels in Italian. American astronomer Percival Lowell sketched similar features and speculated that they were "canals" built by intelligent beings.
More detailed images showed that Lowell was mistaken. But telescopic observations have remained valuable for geologic studies and long-term climate monitoring.
Percival Lowell sketched these drawings of Mars based on his telescopic observations.