Before revision: Mars canals thumbnail|Map of Martian "canals" by Percival Lowell A notable example of pareidolia occurred in 1877, when observers using telescopes to view the surface of Mars thought that they saw faint straight lines, which were then interpreted by some as canals (see Martian canals) .
After revision: Mars canals thumbnail|Map of Martian "canals" by Percival Lowell A notable example of pareidolia occurred in 1877, when observers using telescopes to view the surface of Mars thought that they saw faint straight lines, which were then interpreted by some as canals .