In the late 19th to early 20th century, the Harvard College Observatory set up a field station in Arequipa, Peru to document the skies of the Southern hemisphere.
In the late 19th to early 20th century, the Harvard College Observatory set up a field station in Arequipa, Peru to document the skies of the Southern hemisphere. By Monica Zheng

Astronomical Imperialism: Harvard In the Peruvian Skies

The data collected by Harvard College Observatory in Arequipa in the late 19th to early 20th century, is foundational in the study of astronomy and has furthered our understanding of the cosmos. But this type of cross-continental scientific undertaking cannot be separated from its impact on its workers — both the Indigenous people building Harvard facilities in Peru and the low-paid women astronomers in Cambridge.
By Sarah W. Faber

At a convent atop a hill in Arequipa, Peru, stands a small, white chapel, shaded by two towering trees. Cacti and small pink flowers grow in front of the stone wall lining its entrance. It’s next to the house where the nuns live: a 19th-century mansion, painted cherry red and framed by the outline of the dormant volcano El Misti. And from 1895 until 1927, it housed Harvard’s Bruce Telescope: at the time, the most powerful photographic telescope in the world.

In the late 19th to early 20th century, the Harvard College Observatory set up a field station in Arequipa, Peru, to document the skies of the Southern hemisphere. The data collected from Harvard’s station in Peru has been foundational in the study of astronomy — serving as the basis for discovering the period-luminosity relation, which is used to measure the brightness of stars — and has furthered our understanding of the cosmos. But this type of cross-continental scientific undertaking cannot be separated from its impact on its workers — both the Indigenous people building Harvard facilities in Peru and the low-paid women astronomers in Cambridge.

Social scientist Javiera Barandiarán argues that these sorts of international astronomical research projects have created structures that perpetuate colonialism and leave periphery countries dependent on development capitalism. The case of Harvard’s Boyden Observatory is not just a story of scientific development, but a story of the labor behind its construction and operations.

The Bruce Telescope in Arequipa, Peru.
The Bruce Telescope in Arequipa, Peru. By Courtesy of Harvard Archives

Claiming Mount Harvard

Uriah A. Boyden was a self-taught engineer who made his fortune on the patents of his hydraulic inventions. Upon his death in 1897, Boyden left nearly all of his money, $230,000, to whichever astronomical institution could use it to build a weather station “at such an elevation as to be free, so far as practicable, from the impediments to accurate observations which occur in the observatories now existing, owing to atmospheric influences.”

The money was eventually secured for the Harvard College Observatory by director Edward Charles Pickering. Pickering had long wanted to build an observatory in the Southern Hemisphere so that Harvard astronomy’s observations could span the whole sky. He settled on the Pacific coast of South America because of its location due south of Boston. To lead the expedition Pickering chose Solon I. Bailey, a charismatic and well-respected staff member who had worked his way up from an unpaid internship at the Observatory in Cambridge.

Bailey arrived in Peru in late 1889 with his wife, son, and brother. Employees and equipment — including telescopes and materials for construction and photography — had arrived in the Choisa Valley, imported smoothly and duty-free thanks to Charles Eliot’s connections in the U.S. State Department.

Solon I. Bailey at a telescope.
Solon I. Bailey at a telescope. By Courtesy of Harvard Archives

Local guides led Bailey and his team around the land, past abandoned Inca developments. Bailey wrote, “from many trips taken among these ancient towns later, I should place the population of the valley near Choisa in the days of the Incas at six thousand. To-day there are perhaps 500. This may be an extreme case, but it well illustrates how Peru has changed since she fell into the hands of Spanish conquistadors.”

During one of these days of scouting, after climbing hand-over-foot up a mountain about a kilometer tall, Bailey reached a clear view of the sky that he quickly decided would be the best fit for the observatory. He named it Mount Harvard. Bailey writes simply, “No site was found that presented so many advantages as Mount Harvard, and here I finally decided to place the field station.” There is no record of a sale of land or transference of ownership, nor the original indigenous name for the mountain.

Mansions, Mountains, Mars

Before choosing Mount Harvard, Bailey had met with Peruvian President Andrés A. Cáceres, who ordered the governors to “furnish peons” to assist in transporting astronomical instruments to the new site. Similarly to the American system of sharecropping, debt peonage in Peru went into effect shortly after slavery was abolished in 1854, and was a cycle of debt in which (mostly Indigenous and Black) people were held in service to their contractor, usually a wealthy landowner or the government.

In his journals, Bailey noted that colleagues had warned him against taking advantage of Cáceres’ offer, “as it would cause ill feeling, for the Government compels the peons to do the work without any pay [sic].” But at some point Bailey did choose to use peons. He noted in the annals that “some 10-12 peons” put up the road to Mount Harvard.

Peruvians workers work on the Bruce Building at Harvard College Observatory, Arequipa, Peru.
Peruvians workers work on the Bruce Building at Harvard College Observatory, Arequipa, Peru. By Courtesy of Harvard Archives

Building and starting up the station at Mount Harvard was no easy feat. Food and water had to be hauled to the site from the nearest town, which was eight miles away and 4,000 feet lower. The weather at Mount Harvard was impeding data collection; it was often raining, the station was enveloped in clouds for days at a time between December and March, and it was so cold that their fuel supply was running out.

In 1890, one year after the station was built, Bailey wrote to Pickering in Cambridge that Mount Harvard should be abandoned and the project relocated to Arequipa, a region roughly 600 miles south. Pickering agreed, and decided to give Bailey a break from running operations. Bailey sailed off to France with his wife and son, and Pickering installed his brother, William Pickering, to run the site instead.

William Pickering’s tenure as field director was brief but eventful. Before he arrived, he was afforded $500 to spend on his accommodation if he found the accommodation provided to be lacking. His first missive upon arrival was simply: “Send four thousand more.” When Edward Pickering asked for a justification, William explained that he had bought a tract of land, and actually needed $7,000 to build a house that could sustain his family and servants, as well as $2,000 for the cost of upkeep. Edward reluctantly sent the money along with a note that he expected precise scientific data very soon.

He received no such data. Instead of taking meteorological data, William was using the equipment for a project of his own: attempting to document alien life on Mars. Edward Pickering found out when he saw the photos of Mars appear in a New York tabloid. Edward promptly fired his brother, and Bailey traveled back to Peru to head the Arequipa observatory, where he was met with financial crises and maladjusted telescopes.

Though William had gone, he had already strained the budget with the new construction on the site — the centerpiece of which was a mansion made of white sillar stone from local volcanoes. The roughly 1.5 acres of land, purchased for $750 from a local wealthy landowner, Sr. Polar, had been used communally by the locals of Arequipa.

Though a deed of ownership had been transferred, people continued to farm the land and graze their animals on it. Attempts to keep people out by placing barbed wire around the site proved futile as villagers cleared them away for ease of access. Conceptualizations of private property in communal Andean ayllus differed from Western capitalist understandings.

According to Bailey, locals eventually started to destroy and steal equipment. He asked Pickering for $100 to $300 more to buy more land from Polar on which to build an adobe wall to hold additional telescopes. The walls would also serve another purpose: fortifications for the site during the impending Civil War — by 1893, when Bailey arrived back in Arequipa, tension was stirring among Peruvian dissidents, who were unsatisfied with President Cáceres.

The Metereological Station at Arequipa, Peru.
The Metereological Station at Arequipa, Peru. By Courtesy of Harvard Archives

In addition to the field station in Arequipa which housed the photographic telescope and a lab, Bailey decided that Harvard needed another meteorological station at a higher elevation. He set his sights on El Misti, a nearby dormant volcano that he had tried to climb years earlier, but failed to summit because he was knocked unconscious by altitude sickness.

Eventually Bailey realized that mules were able to withstand the altitude better than humans, and they were used to transport equipment to the top of El Misti with the guidance of some hired workers. The meteorological station on El Misti stood in addition to the field station in Arequipa, and the one member of Bailey’s team who was physically able to summit the mountain went about once a week to collect records and reset the instruments.

“We made a photograph of Misti, including part of the river. An Indian, with a troop of llamas, was just coming up the bank, and he was directed to stand still for a moment,” wrote Bailey about scouting the El Misti station site. “He evidently took us for dangerous people, and the camera for some engine of war, for he stood without moving a muscle until we had finished and begun to pack up, when he fled down the hill as fast as he could drive his animals.”


In January of 1895, Bailey and his family were traveling into the nearby city of Mollendo when a group of revolutionaries wielding revolvers stopped the train with shouts of “Viva Piérola!” The passengers remained locked in the train while the group seized the town, which didn’t take too long, Bailey noted, because there were only 15 soldiers defending it. Bailey wrote that the revolutionaries acted with “great moderation” and “offered us no indignity whatever.” Even still, when the Baileys spent the night at the house of a local shipping agent, the host and Bailey guarded the house with weapons all night.

Arequipa was besieged by the revolutionary faction shortly after the Baileys returned. The astronomers fortified the site and buried the telescope lenses but continued to send someone out each night under the cover of darkness to take observations.

Bailey was not worried about the war. In an earlier letter to Pickering, he joked that he might have to remove lenses from telescopes to turn them into cannons. But after receiving no word from Bailey due to the telegraph lines in Arequipa being cut, Pickering sent a telegram through Eliot to the American minister in Lima telling him to “spare no efforts” in protecting the observatory.

Once the war was over, and Nicolás de Piérola was installed as President, Bailey set up a meeting with him as he had with Cáceres to curry favor. Bailey also opened the doors of the site to local and foreign visitors, and in 1899 installed a public tennis court on the premises.

Back in Cambridge, the plates were being analyzed by a team of all-female astronomers known as the Harvard Computers. Their work consisted of meticulously calculating the brightness of spots on the plates — which were stars — and analyzing spectra.

The Harvard Computers made 25 cents an hour, or around 6.85 dollars adjusted for inflation. This pay rate was deemed unacceptable by many men, leaving the job for women who didn’t have many other employment options available. Male observatory assistants working on similar clerical tasks were paid around 40 percent more than their female counterparts.

The post-war period marked the move into the golden age of the Arequipa observatory. The collection of plates sent to Cambridge from the Mount Harvard and Arequipa stations constitute 25 percent of the world’s total astronomical photographic plates. It was thanks to the plates from Arequipa of the Magellanic Clouds that Henrietta Swan Leavitt, one of the Computers, discovered the period-luminosity relationship, a cornerstone of astronomical research now known as the Leavitt Law.

An astronomical photographic plate taken in Peru from Harvard College Observatory's Arequipa Station.
An astronomical photographic plate taken in Peru from Harvard College Observatory's Arequipa Station. By Courtesy of Harvard Archives

The work at Arequipa was not without problems. The severe physical demands of the site made it hard to retain assistants for long periods of time, and as the team had experienced at Mount Harvard, the cloudy season lasted about four months and made work difficult. Bailey returned to Cambridge in 1900 after his five-year term as director of the Boyden Station, and in 1908, was enlisted by Pickering to find an even better location for the station. Some other astronomers had suggested South Africa, so he sent Bailey with meteorological instruments and three telescopes to scope out a site. He chose Bloemfontein, which had very clear skies and only occasional dust storms and violent thunder.


At the 1893 World’s Fair in Chicago, the Harvard College Observatory showcased photographs from the station in Arequipa. Harvard’s photographs were credited from “Harvard Photometry and Henry Draper Memorial Catalogue of Stars” rather than explicitly the Arequipa Observatory, and no credit was given to the Peruvians who actually took the photos being exhibited. At the event, Peru was only represented as the subject of anthropological research. Ahead of the 1900 World’s Fair, a commission from the Peruvian government asked the Observatory if they could do an exhibit together, partially as an opportunity to showcase Peru’s place as a modern nation on the world’s stage. The request was denied.

Currently, a team at the Harvard College Observatory is working to digitize a century’s worth of astronomical data, totalling half a million glass plates. According to Astronomical Plates Curator Thomas Burns, this amounts to 1.2 petabytes of information — roughly three times larger than Harvard Library’s digital collections.

In digitizing the material from Arequipa, including the written records, Burns says the Observatory is consciously highlighting the overlooked history of the project. In a concrete sense, that means re-transcribing notebooks from Arequipa to disambiguate the observer column to give credit to the people that took the photographs.

But it also means reflecting on the people Harvard’s research has harmed or left out, from Arequipa locals to the women who processed the data — and how to rectify those harms.

The Arequipa Station with El Misti in the background.
The Arequipa Station with El Misti in the background. By Courtesy of Harvard Archives

“The thing that we have to investigate and be very critical of is: What promises did Harvard give before?” Burns asks. “Arequipa we left. Bloemfontein we left. What did that leave do? What was the impact?”

In an 1893 letter from Arequipa to Cambridge, Bailey wrote: “An old priest, who comes here occasionally, was very much surprised to learn that we send our plates of stars to the U.S. He said, ‘Aha! You take our stars and you send them to Cambridge and they have the use of them there, Aha!’ with a very suspicious look.”

— Associate Magazine Editor Sarah W. Faber can be reached at Follow her on Twitter @swfaber.

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