Lowell Observatory

Percival Lowell came to astronomy as an enthusiastic amateur from a wealthy and intellectually serious Boston family — the same Lowell family that produced poet Amy Lowell, Harvard president Abbott Lawrence Lowell, and the mill-town namesakes of Lowell, Massachusetts. Percival was fascinated by Italian astronomer Giovanni Schiaparelli's 1877 observations of what Schiaparelli called canali (channels) on Mars, a term that English-speaking observers translated as canals, with all the implications of artificial construction that the English word carried. Lowell became convinced that Mars was inhabited by an intelligent civilization that had built a planet-wide irrigation system, and he wanted his own observatory to study Mars during the planet's close approaches to Earth.

Lowell hired a young astronomer named Andrew Douglass in 1893 to survey potential observatory locations across the American Southwest. Douglass tested sites in Arizona, New Mexico, and other Western locations for atmospheric clarity using a small portable telescope, and ultimately recommended Flagstaff's Mars Hill as the optimal site. Construction of the original observatory building began in 1894, and the 24-inch Clark refractor telescope — built by the renowned Alvan Clark & Sons firm of Cambridgeport, Massachusetts — was installed in 1896 and remains in working order today. Lowell spent the next 20 years of his life largely at the Flagstaff observatory, publishing books on Mars, the asteroid belt, and the search for a hypothetical Planet X beyond Neptune that he believed must exist to explain orbital irregularities he had observed in Uranus and Neptune.

Lowell died in 1916 without finding his Planet X, but he left an endowment specifically for the continued search. That endowment funded the construction of a new 13-inch astrograph telescope at Lowell Observatory in the late 1920s, and that telescope is the one that a young Kansas farm boy named Clyde Tombaugh would use in 1930 to discover what was eventually named Pluto in honor of Percival Lowell's initials and his role in funding the search.

Clyde Tombaugh was 24 years old in 1930 — a self-taught amateur astronomer from a Kansas farming family who had built his own telescopes from scratch and mailed observational drawings of Jupiter and Mars to Lowell Observatory in hopes of finding professional work. Lowell director Vesto Slipher was impressed enough by Tombaugh's drawings to hire him as a junior observatory assistant in 1929, specifically to operate the new 13-inch astrograph and search systematically for Lowell's hypothetical Planet X. The methodology was painstaking — Tombaugh photographed small sections of the night sky on glass plates, waited several nights, photographed the same sections again, and then used a device called a blink comparator to flip rapidly between the two plates to identify any objects that had moved against the fixed background of stars.

On February 18, 1930, after nearly a year of systematic searching, Tombaugh identified a faint moving object on plates he had taken in January of that year. He confirmed the discovery on subsequent observations and reported it to Slipher and the observatory's senior staff. The discovery was announced to the public on March 13, 1930 — Percival Lowell's birthday — and the new planet was named Pluto a few weeks later, with the first two letters honoring Percival Lowell's initials. Tombaugh became internationally famous overnight as the discoverer of the ninth planet and went on to a distinguished astronomy career; he died in 1997 at age 90, having lived long enough to see the launch of the New Horizons mission that would eventually photograph Pluto up close in 2015.

Pluto's reclassification as a dwarf planet in 2006 by the International Astronomical Union was controversial among Lowell staff and among many Americans generally, but the original discovery's significance was never disputed. The original 13-inch astrograph telescope that Tombaugh used remains at Lowell Observatory today and is one of the highlights of the standard daytime tour. Visitors can see the actual eyepiece through which Tombaugh first observed Pluto's motion and the blink comparator he used to identify the new planet against the background of fixed stars.

Lowell Observatory completed a substantial campus expansion in 2019 with the opening of the Giovale Open Deck Observatory — a roughly 7,500-square-foot outdoor viewing platform with six advanced research-grade telescopes available for public use during evening programs. The Giovale Deck (named for donors Gary and Diane Giovale, who funded the project) represented the largest single addition to the observatory's public-access infrastructure in its history and substantially expanded the evening visitor experience. The six telescopes include a 32-inch reflector, a Dall-Kirkham astrograph, a wide-field refractor, and several specialized instruments for different kinds of celestial viewing.

The deck operates every clear evening when the observatory's evening programs are scheduled — typically year-round, though winter snowstorms can occasionally close evening operations. Lowell staff astronomers and trained docents operate each telescope and adjust them throughout the evening to point at planets, star clusters, nebulae, and galaxies appropriate for the season. Visitors typically rotate through the six telescopes during a 90-minute evening session and see a substantial variety of objects — Saturn's rings, Jupiter's moons, the Orion Nebula, the Andromeda Galaxy, and dozens of other targets are typical sightings depending on season.

Beyond the Giovale Deck, the modern campus includes the Putnam Collection Center (a substantial indoor exhibit space covering Lowell's history and modern research), the historic Slipher Building (where the observatory's research administration is still based), the 1896 Clark Telescope dome (which remains the campus's iconic architectural feature), the Pluto Discovery Telescope dome, and several smaller historic buildings and modern visitor facilities. A new Astronomy Discovery Center building, larger than anything currently on campus, opened in late 2024 and significantly expanded the indoor exhibit and educational capacity.

Flagstaff's designation as the world's first International Dark Sky City in 2001 is genuinely important context for understanding why Lowell Observatory continues to be a serious research institution and why the public stargazing experience is as good as it is. The International Dark-Sky Association is a nonprofit organization that awards Dark Sky designations to communities, parks, and reserves that meet strict standards for outdoor-lighting design, light-pollution reduction, and community awareness. Flagstaff was the first community anywhere in the world to receive the urban-area designation, and the city has continued to refine and tighten its lighting ordinances over the subsequent two decades.

The practical effect is that Flagstaff's outdoor lighting is dramatically different from typical American cities. Street lights are low-pressure sodium or amber LED rather than the white or blue-white LED that most American cities have adopted, and they are shielded to direct light downward rather than horizontally. Commercial signs are restricted in size, brightness, and color. Residential exterior lighting is regulated. The result is that the night sky over Flagstaff genuinely remains dark enough that the Milky Way is typically visible from anywhere in the city on a clear moonless night, which is increasingly impossible in most American urban areas.

For Lowell Observatory specifically, the Dark Sky designation is what allows the observatory to continue serious research from a site that is otherwise immediately adjacent to a city of 75,000 people. For visitors, the practical impact is that the evening stargazing programs at Lowell genuinely show the night sky in something close to its natural state, with thousands of visible stars and clearly visible deep-sky objects that would be invisible from a typical American city.

Lowell Observatory works naturally as either an afternoon-into-evening anchor or as the main draw of an evening visit. The classic plan: spend the morning exploring historic downtown Flagstaff (10 minutes east of the observatory), have lunch at Beaver Street Brewery or one of the downtown restaurants, arrive at Lowell around 2pm for the afternoon daytime tour of the Clark Telescope and the Pluto Discovery Telescope, stay through sunset, and join the evening stargazing program on the Giovale Open Deck Observatory. Total time on-site typically runs 4 to 6 hours for this kind of full visit.

For visitors based in Flagstaff for multiple days, Lowell pairs naturally with day trips to Walnut Canyon National Monument (10 miles east of downtown), Wupatki and Sunset Crater Volcano National Monuments (45 minutes north), the Grand Canyon's South Rim (90 minutes north via Highway 180 or 89), Sedona's red rock country (45 minutes south via Highway 89A), Williams (35 miles west on I-40 and the gateway to the Grand Canyon Railway), and Winslow (60 miles east on I-40, home of the Eagles' Take It Easy corner). Flagstaff functions as the natural high-country base camp for all of these destinations.

For Route 66 road-trippers, Flagstaff and Lowell Observatory are typically the standard overnight stop on the long stretch between Albuquerque and the Grand Canyon. The observatory works particularly well as an arrival-evening activity — drivers arriving in Flagstaff in the late afternoon can check into a downtown hotel like the Hotel Monte Vista, walk to dinner at Beaver Street Brewery, and arrive at Lowell by 8pm or 9pm for the evening stargazing session. The combination of historic Route 66 atmosphere downtown and serious astronomical history at Lowell is one of the most genuinely satisfying evenings available anywhere along the Mother Road.