As the Earth and Mars race in circles around the Sun, with Earth on the inside track, Mars laps the Earth about every 26 months.

The two planets come relatively close together at that point, called an opposition (Mars and the Sun are on opposite sides of Earth), and exceptional viewing occurs, not only because Mars appears bigger and its surface features can be more easily examined, but also because the entire illuminated side of red planet faces the dark side of Earth.

Accordingly, Percival Lowell spent time during each opposition observing the "canals" on Mars, and the time in-between writing and lecturing about what he’d seen.

In his 1897 article, Atmosphere: In its Effects on Astronomical Research, Lowell described his secretary Miss Leonard as a “neophyte.” The fact that her untrained eye saw the canals on Mars proved that the canals actually existed, he explained. Her more primitive form of vision – not influenced by prior knowledge or viewing experience – was the opposite of what he called his own “intelligent eye.”

Miss Leonard's typewriter at Lowell Observatory

It was Miss Leonard’s job to type and help edit his manuscripts; as she prepared this article, she very likely took umbrage at his less-than-flattering words.