How the rise (and fall) of Pluto put Flagstaff’s observatory on the map
It is a mere speck, an orbiting ball of ice far beyond the reach of warming solar rays. Just 1,420 miles across, it’s smaller than our moon, and nearly imperceptible at an average of 3.6 billion miles from the sun.
Yet more than 80 years ago, this cosmically insignificant object was larger than life and riveted a nation in need of good news.
On March 14, 1930, as the 5-month-old stock-market crash continued to destroy jobs and lives, newspapers across the country ran front-page headlines of a stunning discovery.
“Ninth planet discovered on edge of solar system; first found in 84 years,” the
New York Times announced. In Phoenix, The Arizona Republican blared, “Discovery of Ninth Planet Ends
25-year Quest by Lowell Men.”
Suddenly, people were pulling out atlases to find Flagstaff, Arizona, home to the planet-finding Lowell Observatory and Clyde W. Tombaugh, an assistant credited with the discovery.
The number of planets had just increased by 12.5 percent thanks to this mysterious outlier. Dubbed “Planet X,” it captured the imagination like nothing else, and thousands of people mailed or wired potential names for an object initially believed to be larger than Jupiter.
About seven weeks later, Planet X had a name: Pluto, the Roman god of the underworld.
Time magazine would herald Pluto as the greatest scientific discovery of the decade.
Pluto continues to make news to this day, from being kicked to the curb as a planet to a starring role in a years-long NASA mission.
It remains Lowell Observatory’s legacy, and visitors still come to peer through the telescope that put Pluto and Flagstaff on their respective maps. They imagine Tombaugh’s amazement the fateful night he scanned the skies and spied a distant sphere moving across the heavens.
And they find that perception is as far from the truth as Pluto is from the sun.
Unlikely path to fame
Even as his hands were firmly planted in the earth, Clyde Tombaugh’s eyes were always skyward.
The stars and planets mesmerized the Kansas farmhand like crops never could. He’d even built his own telescope, and was surely the only resident of tiny Burdett who spent nights jotting notes and sketching planets as others went to bed early, preparing to rise with the sun.
Tombaugh considered astronomy more of a hobby than career in 1928, when he affixed a 2-cent stamp to an envelope addressed, “Lowell Observatory, Flagstaff.” Inside he stuffed examples of his work and asked for a job.
By early 1929, he was on a train to Flagstaff. Lowell’s director, V.M. Slipher, offered Tombaugh a position that would include “uncomfortable hours” with the instruments, if not some “janitor work.”
At the time, Lowell astronomers had devoted themselves to a project designed to redeem their late founder.
Percival Lowell’s belief that Mars was home to intelligent life had been long discredited. He believed Martians had carved canals to bring water from polar ice caps to the planet’s arid middle — a theory he admitted was wrong in 1907, more than a decade after first positing it.
As a result, astronomers paid little attention to Lowell’s claim of a ninth planet, one so massive that it was altering the orbits of Neptune and Uranus.
When Lowell died in 1916, so did the search for Planet X — until Slipher decided in 1927 that it was time to redeem the observatory’s namesake.
In the final days of 1928, Slipher penned a lengthy, rambling note to a Kansas farmhand who had a knack for astronomy. He offered the 23year-old Tombaugh a job, demanding much and expecting little.
He had no idea what was in the stars.
A tedious exploration
Searching for a planet that might or might not exist was a tedious, mindnumbing job, Lowell’s astronomers knew. Naturally, it should fall to their young assistant, who was more apprentice than anything else.
Starting in April 1929 and for the next 10 months, Tombaugh was in charge of developing and analyzing photos taken by a telescope built to find the mysterious planet theorized by Lowell.
Tombaugh did so without complaint, knowing how the search was personal for the Flagstaff astronomers. It was their mission to put Planet X, and Lowell Observatory, on the map.
On clear nights, the astronomer-in-training slipped a 14-by-17-inch glass photographic plate into the base of the telescope, exposing it to the stars for up to four hours. When developed, it looked like a snapshot of thousands of grains of pepper, one dot nearly indistinguishable from another.
Yet if Planet X existed, it would eventually appear on one of the hundreds of plates being amassed over days and weeks. The trick was to spot it.
To do so, Tombaugh used a Blink Comparator, See PLUTO, Page 9A
“It feels rather strange to be famous. Tho (sic) I don’t feel to be so aware of it because I don’t see multitudes. Flagstaff has become use to it by now.” CLYDE TOMBAUGH DISCOVERER OF PLUTO
which allowed him to switch between two plates exposed five or six days apart. Stars remained in place, so he was looking for a stray speck that moved slightly.
Focusing 1 square inch at a time, Tombaugh spent hours on the comparator several times each week. Over time, he discovered everything from asteroids to bits of dust on the lens. The click of the device was so constant that it became part of the background noise, like footsteps or the hum of the lights.
Until 4 p.m. Feb. 18, 1930, when the clicking stopped.
Discovery, secrecy
Astronomer Carl Lampland looked up from his desk in the observatory, curious about the odd silence. It stretched on to 15 minutes, then 30, finally 45. Perhaps Tombaugh had taken up another task, or needed a break. So when Lampland heard the assistant call for him, he quickly joined Tombaugh in the comparator room.
Tombaugh also fetched Slipher, telling the director, “I have found your Planet X.”
Tombaugh had been measuring and plotting and analyzing one particular speck of the thousands on the two plates. For the next hour, the three men did the same thing, noting size and brightness and movement.
Everything backed up Tombaugh’s finding. The gravity of the situation sank in. “It hit me like a ton of bricks,” Tombaugh would tell an Arizona Republic reporter 60 years later, the moment as vivid as ever.
Slipher ordered Planet X be kept secret until, unlike Martians, its existence could be proved beyond all doubt.
Clouds thwarted their overwhelming desire to point the telescope toward Planet X and start work on a project that would vindicate Lowell Observatory.
Instead, Tombaugh hiked down to Flagstaff, hoping to push Planet X from his mind even as he knew his life would never be the same.
He stepped into the Black Cat Cafe (now a sushi restaurant), where he was a familiar face. After dinner, he headed to the Orpheum Theater to see “The Virginian,” a Western starring Gary Cooper.
Planet X remained a stubborn resident in his mind, and would remain so even as the rest of the world was finally let in on the secret.
System’s new star
On the evening of March 12, 1930, Slipher sent a telegram to astronomers at Harvard College Observatory, which was responsible for announcing notable discoveries.
The next day — Percival Lowell’s birthday — the world heard about Planet X.
It would be yet another day before the news arrived in Burdett, Kansas, rolling in on the noon train. Word spread quickly of the discovery by the town’s new most famous son. “Goodness it most took us off our feet,” Adella Tombaugh wrote to her son. “You know everyone was talking about it.”
The Tombaughs became instant celebrities in their hometown. Adella wrote that “telephone calls came so thick for a while they almost swamped us.”
Tombaugh seemed to take it in stride, barely mentioning his newfound attention in a letter home 11 days after the announcement.
“It feels rather strange to be famous,” Tombaugh wrote. “Tho (sic) I don’t feel to be so aware of it because I don’t see multitudes. Flagstaff has become use to it by now.”
The discovery put Tombaugh’s life in a new orbit. Shortly after his arrival in Flagstaff, he wrote his family that he’d stay three years before returning to farming, where his roots lay.
Pluto launched him toward a college education and a long career as an astronomer and teacher.
Pluto would have an altogether different fate.
Pluto’s demotion
Slipher’s telegram to Harvard left out some details that would eventually come into play, because size would eventually matter. While it was impossible at the time to determine the planet’s size, the astronomers knew it was not large enough to affect the orbits of Uranus and Neptune, as Percival Lowell had theorized, according to Lowell Observatory historian Kevin Schindler.
In 1930, planetary size was irrelevant. Space was still a mystery, providing fertile ground for dimestore novelists writing of trips to Mars and alien invasions. But the discovery of a far-off orbiting sphere trumped science fiction.
Still, Tombaugh and his colleagues believed Planet X was two to three times the size of Earth.
Doubts arose with further study, Schindler said. They worried it might not be large enough to be a planet at all, even if a precise scientific definition didn’t exist.
They kept those concerns to themselves.
“They were working at an observatory built on the belief Mars had life,” he said. “They didn’t need to give astronomers more reasons to look down on them.”
Pluto lived a charmed planetary life for decades. It starred in science textbooks and solar-system mobiles. Even as astronomers determined Pluto’s diminutive size, it remained a member of the planetary club, as the runt of the litter.
That just made it more endearing, Schindler said, and thus difficult to accept when, in 2006, Pluto was kicked to the celestial curb. The International Astronomical Union voted overwhelmingly to reclassify Pluto as a dwarf planet. “Pluto is dead,” Mike Brown, a Caltech researcher, told reporters gleefully after the vote. “Pluto is not a planet. There are finally, officially, eight planets in the solar system.”
Tombaugh, who became a college professor, had died in 1997 and thus didn’t have to witness the demotion, even as Lowell Observatory visitors arrived with sympathetic looks.
“They asked if we were OK. I told them we’d be fine,” Schindler recalled, noting that the Lowell gift shop sells T-shirts saying, “When I was your age, Pluto was a planet.”
The IAU vote put Pluto back in the spotlight, setting the stage for its starring role 10 years later, when the New Horizons spacecraft flew by, sending back photos of the shimmering ball of ice.
“Those photos really put Pluto in perspective,” Schindler said. “I wouldn’t be surprised if some people regretted their vote (to reclassify Pluto) when those came in.”
Today, a new generation is searching for the large planet that computer simulations insist is out there. And the hunt is open to everyone.
In February, NASA created Backyard Worlds, a website urging people to look through an astronomical flipbook and report any moving specks. Without a Tombaugh to do the demanding and tedious work, the space agency decided the best way to go was to crowdsource the job.
Tombaugh, however, had the last word. When New Horizons sped toward and then past Pluto, it carried a bit of Tombaugh’s ashes.
And they were much more than a speck.