Observers in the nineteenth century reported seeing many straight-line features crisscrossing the surface of Mars, and these were interpreted as canals constructed by intelligent beings. What is the most likely present-day explanation for these observations?
A)stationary linear cloud formations (mountain lee wave clouds) and weather fronts, rotating with the planet
B)optical illusions caused by vague shadings on the planet surface
C)rifts at the boundaries of geological tectonic plates
D)lines of volcanoes similar to those of the Hawaiian Islands on Earth

Question

Quizplus · Accepted Answer

The straight-line features seen on the surface of Mars were likely optical illusions caused by vague shadings on the planet's surface. This theory is supported by modern spacecraft observations, which have not detected any evidence of artificial canals or other intelligent constructions.

Observers in the Nineteenth Century Reported Seeing Many Straight-Line Features