Percival Lowell spent years mapping spoke-like features on Venus that turned out to be the blood vessels of his own retina, and he popularized a network of Martian canals that never existed. Yet the same man pioneered high-altitude observatory placement and set in motion the discovery of Pluto. This episode follows the Boston Brahmin from a Harvard mathematics degree and six years running the family cotton mills, through a decade in Korea and Japan writing about psychology and imagination, to the founding of Lowell Observatory in Flagstaff, Arizona in 1893.

We explain why atmospheric seeing matters more than city lights, how a mistranslation of Schiaparelli’s canali primed Lowell to see engineered canals, and how a stopped-down 24-inch refractor turned into an ophthalmoscope. We then cover his final decade searching for Planet X through gravitational perturbations, the team of human computers led by Elizabeth Williams, Clyde Tombaugh’s 1930 discovery of Pluto, and the later realization that the Neptune wobbles were a data error, making the find a coincidence. We close with Lowell’s imprint on H.G. Wells, Edgar Rice Burroughs, Ray Bradbury, and the Pluto symbol itself.

• Why Lowell chose thin, dry, high-altitude air and sealed refracting telescopes for planetary work
• How gestalt pattern-finding and confirmation bias stitched Martian craters into straight lines
• How shrinking a telescope’s aperture to three inches projected his own retinal veins onto Venus
• Why Pluto’s tiny mass and Voyager 2’s measurement of Neptune undermined the Planet X math
• How a spectacularly wrong theory became the mythology of twentieth-century science fiction