Percival Lowell's Lonely Vigil: The Observatory That Found a Planet

Percival Lowell was a Boston Brahmin, a graduate of Harvard, a successful author of books about Japan, and a man who became convinced in the eighteen nineties that Mars was inhabited. Not speculatively inhabited. Inhabited, he believed, by an intelligent civilization that had constructed an elaborate network of canals to carry water from the polar ice caps to the equatorial deserts as their planet dried out. He built an observatory on a mesa above Flagstaff, Arizona, in eighteen ninety-four to prove it.

He spent the rest of his life trying to. He mapped the Martian canals in meticulous detail, publishing three books on the subject and sustaining a career-long argument with the astronomical establishment, which increasingly questioned whether the canals existed at all. He died in nineteen sixteen, the argument unresolved in his favor. The canals, as subsequent observation confirmed, are optical illusions. They are not there.

What Lowell built at about thirty-five degrees north latitude and seven thousand two hundred feet of elevation turned out to be good for other things. Lowell Observatory sits on Mars Hill, on land that in eighteen ninety-four was dark enough for the work he had in mind, in air clear enough that it remained productive for serious science well into the twentieth century.

In nineteen thirty, a twenty-four-year-old self-taught astronomer from Kansas named Clyde Tombaugh was working at Lowell's observatory as an assistant. He had been hired after sending homemade drawings of Mars and Jupiter to the observatory's director. On February eighteenth, nineteen thirty, Tombaugh discovered a new planet in the outer solar system by comparing photographic plates taken six days apart and noticing a tiny point of light that had moved. He named the discovery for the Roman god of the underworld. The name Pluto was submitted by an eleven-year-old British schoolgirl named Venetia Burney, whose suggestion was cabled to the observatory and accepted.

Coconino National Forest surrounds the plateau the observatory sits on. The forest's elevation and the distance from city lights produced the darkness that made Tombaugh's work possible. He found Pluto, classified as the ninth planet for seventy-six years and reclassified as a dwarf planet in two thousand six, at an elevation the ponderosa pines of the Coconino plateaus helped keep dark.