One of the nation's most famous observatories turns 125 years old. Let's all wish it a happy birthday!

Percival Lowell observes
Percival Lowell observes Venus during the daytime on October 17, 1914, from the observer's chair of the Clark Refractor.
Lowell Observatory

One hundred and twenty-five years ago today, on May 28, 1894, Percival Lowell, scion of a wealthy Bostonian textile family, arrived in Flagstaff, Arizona. There, he established a private observatory, just in time for that year's opposition of Mars. Fascinated by Italian astronomer Giovanni Schiaparelli’s work on Mars, Lowell’s quest was to find intelligent life on the Red Planet. To do this, he sent a young astronomer named Andrew Douglass west to test out potential observing sites. Douglass set up camp at 14 "stations" around Arizona, using a 7-foot-long, 6-inch refractor to study the skies. Station 11, a mesa west of Flagstaff's downtown, was selected as the future site of the observatory based on Douglass's reports.

Initially, Lowell carried out his work in Arizona using borrowed instruments — an 18-inch refractor from Harvard College Observatory and a 12-inch refractor from John Brashear — but in 1895, he commissioned Alvan Clark & Sons of Cambridgeport, Massachusetts, to build a 24-inch refractor for the observatory. The Clark Refractor, as it came to be known, arrived at Lowell’s observatory in 1896. Naught came of Lowell’s Martian endeavors, but the observatory spawned a plethora of groundbreaking discoveries in the decades that followed.

For instance, instruments at Lowell Observatory played an important role in the measurements that demonstrated the expanding nature of the universe. Although the discovery of galaxy redshift is most often attributed to Edwin Hubble, it was Vesto Slipher, using the Clark coupled with a spectrograph, who first noted the redshift of spectral lines of galaxies in 1912.

Clyde Tombaugh used this telescope to discover Pluto in 1930.
Packbj / CC BY-SA 4.0

Perhaps the most famous discovery to come out of Lowell Observatory was that of Pluto in 1930. Lowell himself was convinced that there must have been a trans-Neptunian planet, and he spent the years between 1902, when he first postulated the idea, until his death in 1916 intermittently searching for it. But like life on Mars, this, too, remained elusive to Lowell. In the mid-1920s (after squabbling over Lowell’s estate was settled) Percival’s  brother, A. Lawrence Lowell (then President of Harvard University) funded a telescope and dome specifically for the search for the elusive Planet X. In 1929, Slipher, then the director of the observatory, hired a young, self-taught astronomer, Clyde Tombaugh, to resume the search. Tombaugh discovered Pluto shortly after, in early 1930, and the announcement was made on March 13, 1930, Lowell’s birthday.

In the 1960s, the Clark was used to create detailed maps of the Moon for the upcoming Apollo lunar missions. Several of the Apollo astronauts visited Flagstaff not only for lunar observations and interaction with the scientific staff of the observatory, but also for geological training in the area, most notably in Meteor Crater.

Nowadays, the Clark Refractor and the Pluto Telescope are not in scientific use. But both have been restored to their former glory. The Clark underwent an extensive restoration between January 2014 and August 2015. Operations included: dismantling the tubes and painting them inside and out; applying a new set of hand-painted numbers and measuring marks to the setting circle; the glass lens of the telescope was removed for the first time since 1895 for cleaning. The Pluto Telescope was restored by the same team in 2017 — they not only restored the historic telescope, but they also took care of the wooden dome. (The Pluto Telescope was returned to the observatory in the 1990s, after a stint at the Anderson Mesa dark-sky site.)

The Alvan Clark Dome houses the 24-inch Clark Refractor.

Lowell Observatory is a remarkable mélange of cutting edge scientific work and astronomical outreach at the highest level. Located on the appropriately named Mars Hill just west of downtown Flagstaff, the main observatory campus houses the Clark and the Pluto telescopes, as well as the Rotunda Museum and the Putnam Collection Center. Along with the two telescopes, all these facilities are open to visitors (but check opening times). On Anderson Mesa, some 12 miles as the crow flies southeast of Flagstaff, the observatory operates four research telescopes, including an optical interferometer in conjunction with the Naval Research Laboratory. On the peak of Happy Jack, just past Anderson Mesa, is the 4.3-meter Discovery Channel Telescope.

With a staff of some 16 astronomers, research at Lowell covers a wide variety of topics. Lowell has a long, historical tradition on the research of small bodies in the solar system, which is still active today. They have also stepped farther afield, and are also involved in exoplanet studies. In stellar astronomy, researchers cover the evolution of massive stars, as well as trying to understand our Sun better through detailed photometric and spectroscopic observations of Sun-like stars. Stepping outside our galaxy, Lowell astronomers also address the puzzling question of star formation in dwarf galaxies.

The 4.3-meter Discovery Channel Telescope is on the peak of Happy Jack, just past Anderson Mesa southeast of Flagstaff.
SSR2000 CC BY-SA 3.0

But, important as research is, Lowell Observatory offers much more. Staff at the facility conduct a Native American Astronomy Outreach program. Multiple camps are offered for children of all ages. And the observatory is active in promoting dark skies. In September 2018, Lowell Observatory broke ground on the 4,300-square-foot Giovale Open Deck Observatory (GODO). GODO, which is slated to open to the public in late 2019, features an observing deck six telescopes for public viewings. Lowell sees more than 100,000 visitors per year, so this expanded viewing facility will be put to good use.

You can visit the observatory throughout the year, but bear in mind that the observatory is closed on major public holidays. You can also become a member of Lowell Observatory, which will allow you to stay up-to-date with everything going on, and you’ll receive the Lowell Observer, the quarterly newsletter.

Join us as we wish "Happy Birthday" to Lowell Observatory — may there be many more years of great discoveries and inspiring outreach!


Image of Stephen Gagnon

Stephen Gagnon

May 28, 2019 at 3:41 pm

I assume the date for the first photo is wrong? Maybe 1914 rather than 1814?

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Monica Young

May 28, 2019 at 9:14 pm

Yes indeed, thanks for the catch!

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May 31, 2019 at 5:36 pm

I've enjoyed being a contributor at Lowell while completing my second Masters degree in astronomy. I researched the Lowell archives as part of my paper on Mr. Lowell. I was pleasantly surprised to discover how the first evidence for an expanding universe was done by V.M. Slipher. I got a rare opportunity to view these important documents and thoroughly enjoyed the opportunity,, Happy birthday Lowell!

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Diana Hannikainen

June 5, 2019 at 8:57 am

Hi. Thank you for sharing your experiences at Lowell! They sound inspiring.
Best, - diana

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June 2, 2019 at 10:13 am

Thanks for an interesting article on Lowell Observatory.

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Diana Hannikainen

June 5, 2019 at 8:58 am

You're welcome!

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