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Photo: Clyde Tombaugh stands with one of his homemade telescopes.

The eldest of six children, Clyde Tombaugh was born on a farm near Streator, Illinois. He began helping his father around the farm at an early age, planting corn, threshing oats and wheat, and various other labor-intensive tasks. He loved reading in his spare time, particularly on the subjects of geography and history. Exploring the world, both in the past and the present, helped make small-town farm life feel a little less small. When Clyde reached his teenage years, however, the world wasn’t enough—the thought of what lay beyond it captured his imagination, and astronomy took over as his favorite interest. Clyde was lent a three-inch telescope and an astronomy book by his Uncle Lee. Clyde would later say it was this book that introduced him the astronomers who would become his heroes: Galileo Galilei, William Herschel, and Percival Lowell.

In 1920, Clyde’s father and uncle purchased a 2¼ -inch telescope from Sears-Roebuck, which Clyde would use to view the cosmos as often as he could. Two years later, the Tombaugh family relocated to Burdette, Kansas, in search of better farming conditions. There, Clyde was overjoyed to discover that the dark skies provided ideal viewing conditions for his telescope.

Clyde became adept at building his own facilities to suit his various interests around the farm, including a football field and tennis court in the family’s pasture, and of course, his own telescopes. The first telescope he built was an 8-inch reflector, constructed with pine board tubes and repurposed farm machinery. Without a temperature-constant environment to test the telescope in, the final product fell short of Clyde’s expectations. To improve his mirror-making capabilities, he used a pick and shovel to dig an underground testing room that doubled as a storage cellar and tornado shelter. After he cemented the walls and ceiling, it became the perfect place to grind telescope mirrors into the right figure.

Clyde Tombaugh, standing at the entrance to the Pluto Discovery Dome.

In February of 1927, he built a 7-inch reflector that he sold to his uncle. He used the money to begin building a 9-inch telescope, which he finished early in 1928. That same year, the Tombaugh family’s crops were destroyed by a hailstorm, and Clyde realized that the farm life wasn’t for him. He was offered a job by a Wichita telescope maker, but before he could accept it, an even better offer fell into his lap. Clyde had been reading some of his older issues of Popular Astronomy Magazine when he saw an observation report on Mars written by staff members from Lowell Observatory. Inspired, he sent some of the drawings he’d created while observing the planets to V.M. Slipher, then Lowell Observatory’s director. After exchanging several letters with Slipher, Clyde received one that would change his life forever. In it, Slipher offered him a position at the observatory on a trial basis, stating that if he could prove his worth to the observatory, he would be offered a more permanent position there.

As we now know, Clyde would go on to discover Pluto, the fabled “Planet X” that Percival Lowell had spent much of his life searching for, within a mere few months of rekindling the search. He then earned bachelor’s and master’s degrees in astronomy from the University of Kansas, fulfilling his lifelong dream of attending college. Clyde would study astronomy for the rest of his life, even after leaving Lowell Observatory in 1945. He taught astronomy at New Mexico State University from 1955 until his retirement in 1973. During World War II, he contributed his experience to the effort by teaching naval personnel navigation at Northern Arizona University and working at White Sands Missile Range. He was inducted into the International Space Hall of Fame in 1980. He died on January 17, 1997, in Las Cruces, New Mexico, at age 90. A small portion of his ashes was placed aboard the New Horizons spacecraft, which flew by Pluto in 2015.

Photo: The Pluto Discovery Dome | Sarah Gilbert

Construction on the building known today as the Pluto Discovery Dome was completed in September of 1928, 11 years and 10 months after the death of observatory founder and Planet X seeker Percival Lowell. Though Percival himself would not live to see his Planet X found, this unassuming, two-story telescope dome made of local basalt rock is where the decades-long quest would finally come to an end.

A New Beginning

The fevered search for Planet X was placed on hold for nearly a decade after Percival’s passing in November of 1916, due large in part to a tense legal battle between the observatory and his widow, Constance Lowell, concerning the contents of his will.  This, coupled with the onset of World War 1, brought the observatory to the brink of financial ruin. By 1927, however, the role of sole trustee had been passed onto Roger Lowell Putnam, Percival’s nephew. Determined to bring the observatory back to prominence after a period of financial hardship and low morale, Roger resurrected his uncle’s tireless search for the 9th planet in our solar system. To accomplish this, he enlisted the help of then-director V.M. Slipher. While Slipher planned out the construction of a telescope dome, Roger went about searching for a telescope to inhabit it.

Building a Piece of History

For the location of the telescope dome, Slipher chose a hill located 100 yards west of the observatory’s administration building (now known as the Slipher Building), on land leased from the U.S. Forest Service. This land, as well as the acres behind it, would later become observatory property. Construction on the dome began in early 1928, lead by observatory instrument maker Stanley Sykes. Stanley used a design very similar to the one that his brother Godfrey had used to construct the Clark Telescope Dome decades earlier, employing the same inverted bucket shape for the dome’s roof. The most significant difference in the new design was the addition of a second story, where the telescope itself would be housed and operated. The walls were constructed with cement and Malpais rock* collected from the observatory grounds.

An original sketch of the 13″ Lawrence Lowell Telescope.

Meanwhile, Roger searched for a telescope manufacturer to make use of three partially figured, 13 inch-diameter glass discs acquired from the estate of recently-deceased optician Joel Metcalf, who had been working on the discs at the time of his death. After looking into several options, Roger chose Robert Lundin of Alvin Clark & Sons, whose father had assisted in the construction of the Clark, for the task of assembling a 40-inch reflector to be used in the renewed search for Planet X. The telescope would be an astrograph, meaning that it would be designed solely for the purpose of taking photos of celestial objects. The scope was officially named the Lawrence Lowell Telescope, after Percival’s brother, Abbott Lawrence Lowell.

*A type of basalt found in the Southwestern U.S., Mexico, Spain, and other Spanish-speaking regions of the world. Many of the buildings on our Mars Hill campus and around the town of Flagstaff are constructed with it!

Not in Kansas Anymore

While construction on the telescope and its dome progressed, Slipher received a letter from Clyde Tombaugh, a 23-year-old farm boy from Kansas asking for a professional opinion on the sketches he had made while observing planets through his homemade telescope. Impressed, Slipher exchanged several letters with Tombaugh before offering him a job at the observatory on a trial basis. Slipher was somewhat vague about what Tombaugh’s responsibilities would include, alluding to photography and janitorial work, but stated that he might be offered a more permanent position at the observatory if he could prove his usefulness. As history would show, Tombaugh would go on to prove his worth and then some. He accepted Slipher’s offer and arrived in Flagstaff on January 15, 1929, two weeks after receiving the letter.

Clyde Tombaugh at the guide scope for the 13″ astrograph.

The astrograph and its dome were completed the following month of the same year, and the first exposure was taken on February 16. It was in this dome that Clyde would spend many cold, tedious nights alone, guiding the telescope in search of the elusive Planet X. On one of these such nights, Clyde found himself suddenly feeling very warm and sleepy in the otherwise freezing telescope dome. Had he not recognized this as a sign of hypothermia setting in, he might have frozen to death. On another night, he was trapped inside the dome for several hours while a hungry mountain lion prowled outside. However, these hardships would pay off in a big way on February 18, 1930—exactly 1 year and 34 days following the date that Tombaugh first began his employment at Lowell. He discovered Planet X, which he would later name Pluto, while comparing two exposures he had taken with the astrograph.

Today, the Pluto Discovery Dome stands as a monument to an unforgettable moment in astronomy history. Though the Lawrence Lowell Telescope is no longer used for observation, it was refurbished in 2017 along with the dome to ensure that its legacy can be preserved for generations to come.

The Pluto Telescope before it was refurbished in 2017.

The Pluto Telescope after being refurbished.

New Additions

If you look closely at the telescope, you’ll notice a red boxing glove attached to its metal arm. Ralph Nye, who maintained the Lowell telescopes in the 1990’s, was working on the telescope when he hit his head on the end of the arm. This made him see the wrong kind of stars, so he added the glove as a cushion to prevent it from happening again.

Hidden in a cabinet beneath the motor that drives dome movement is a time capsule. It contains Pluto memorabilia including scientific publications, a hat Clyde Tombaugh wore while observing, and a pencil used by scientists during the 2015 New Horizons Mission. Created in collaboration with New Horizons Principal Investigator Alan Stern, the capsule is to remain sealed until an orbiter is sent to explore the surface of Pluto.

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@lowellobservatoryWhat’s in that time capsule? And how did that boxing glove get up there? 🤔 The observatory is full of mysteries, but our blog may have some answers.♬ Moonlight Serenade – Glenn Miller