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On Wednesday morning, it wasn’t the faint glimmer of distant stars, but bright winter sunlight that flooded into the wood-paneled dome of Lowell Observatory’s Pluto Discovery Telescope.

The structure’s wooden shutters had been thrown open for a crane arm to reach through and carefully extract the telescope’s 7-foot, 350-pound tube, counterweights, and giant steel mount from their astronomical nest.

The removal marks the beginning of Lowell’s yearlong renovation of the telescope, used by Clyde Tombaugh to first spot Pluto 87 years ago, as well as its dome.

With visitation at the observatory growing -- in 2016 alone, Lowell saw a record 100,000 visitors -- and the recent focus on Pluto spurred by the New Horizons mission, Lowell thought it was time to give the aging telescope some much-needed TLC, said Kevin Schindler, the observatory’s public information officer.

The $155,000 renovation will be funded through crowdsourced dollars, private donations and grants.

A century of stargazing

The Pluto Discovery Telescope and its dome were built on Mars Hill in the late 1920s for the express purpose of finding “Planet X,” the ninth planet that observatory founder Percival Lowell insisted had yet to be discovered. The instrument was used by Tombaugh and others at Lowell’s Flagstaff campus until the 1970s, when it was moved to Anderson Mesa to take advantage of darker skies. It was reinstalled at Lowell in 1995 and was last used for astronomical observation in 1997.

Since then, the instrument has been sitting there, “basically gathering dust,” said Ralph Nye, the mechanical engineer at Lowell who is heading up the restoration project.

“We would like to make it knock people's socks off,” Nye said of the renovation. “It’s a relic of the past that put us on the map because of the Pluto discovery and it should be taken care of properly and preserved.”

While the restoration process will be similar to what was done on the Clark Telescope two years ago, much more work is needed on the Pluto Discovery Telescope’s dome, Nye said.

Water that drips down the structure’s tin roof gets absorbed by the porous rock exterior, causing plaster inside to flake off. The tin roof siding is coming apart as well, leading to leaks that are causing water damage to the historic wood paneling inside.

“When it’s raining you can hear it, drip drip drip,” Nye said.

The panels, which date back to the 1930s, are different dimensions than those made today, so the observatory has to buy a $600 saw to cut custom boards that match the others, then go through a process of antiquing them, Nye said.

The entire structure will also be weatherproofed.

On the telescope itself, all the pieces have been removed to be tested, cleaned and refurbished or replaced if needed. The lens will be cleaned, photographic plate holders will be cleaned and repaired and the electrical system will be updated. The telescope’s entire exterior needs a paint job as well, Nye said.

New educational exhibits also will be added to the dome once the telescope is finished.

Future use?

Known as an astrographic camera, the Pluto Discovery Telescope has three 13-inch lenses that focus light on a single glass photographic plate. Producing each image required an exposure time of about an hour. It was the glass negatives of these images that Tombaugh, as a young observatory assistant, analyzed using the Zeiss blink comparator to find Pluto.

The lens system was crafted by an experienced optician with Alvan Clark & Sons, the maker of Lowell’s 24-inch and 42-inch telescopes. While that part is “beautiful,” Nye said everything else was kind of scrounged together and built in-house because the observatory didn’t have much money to spend.

“They built it to do a job without caring what it looked like,” Schindler said. “It was 80 years ahead of its time.”

After restoration is complete, Nye said he would like to see the telescope put into use again to produce color images of the night sky. While that final purpose is still under discussion, Nye put forward a good argument.

“The telescope will be better taken care of if it’s actually used” he said, “You'd be surprised what old lenses can do.”

Though the Pluto Discovery Telescope will be removed from the dome during restoration work, the facility will be open from time to time for public tours.

Emery Cowan can be reached at (928) 556-2250 or


Environment, Health and Science Reporter

Emery Cowan writes about science, health and the environment for the Arizona Daily Sun, covering everything from forest restoration to endangered species recovery efforts.

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