Picture of desk with dark blue print, brushes, and gold leaf for gilding.

How notes from the mothers of astronomy were reclaimed in art

On glass negatives of distant starscapes, women scientists analyzed discoveries. Their work was nearly erased, until an artist saved it.

Artist Erika Blumenfeld chose materials forged by stars. Gold—now known to be a product of stellar explosions—gilds the marks of Harvard College Observatory’s “women computers.“ The deep blue paper bearing those marks is a cyanotype, its inky color the product of two separate chemical-emulsion applications each exposed to sunlight for 20 minutes.
Photograph by Jake Eshelman

The print that artist Erika Blumenfeld shows me is an expanse of deep blue, a rich color that speaks of romance and night. It’s stippled with gold marks, some as lines, some as arrows, some as dots. Her art is formed by ink on paper—but it’s rooted in century-old artifacts, inspired by unsung astronomy pioneers, and animated by a quest to understand light.

At the Harvard College Observatory in Cambridge, Massachusetts, three floors of metal cabinets house more than 550,000 glass plates, most of them eight by 10 inches, a photographic negative format dating from the mid-19th century. These plates recorded astronomical data from telescopes trained on celestial regions and objects. One side bears the print of light from distant stars; the other side had been marked with equations, arrows, circles, letters, and other notations by women who were hired to interpret the data. 

From 1885 until the 1950s, hundreds of so-called women computers studied the plates. They discovered how variations in brightness of specific stars revealed their energy output, a relationship that provided a way to measure great distances. They examined a star’s light spectrum and determined that the intensities of the star’s colors indicated its chemical composition. They counted and cataloged galaxies. With such discoveries, these women laid the foundation for modern astrophysics. 

They left marks of many kinds: on some of the plates, only a few arrows or characters; on others, notes from conversations between women across decades, each striving to better understand the universe. 

Then the marks were removed from roughly 470,000 plates. 

So that the world’s researchers could access the plates’ historic trove of astronomical data, the collection needed to be digitized. In the early 2000s, Harvard astrophysicist Jonathan Grindlay began a project that’s now nearly complete: Digital Access to a Sky Century @ Harvard, or DASCH, an archive of digital scans from the bulk of the collection. 

According to Grindlay, getting the clearest image of a glass plate’s astronomical data requires eliminating all marks on the other side of the plate before scanning. This is the process: Each plate is placed on a table with its nonastronomical-data side—that is, the area where the women computers had written their observations, measurements, and notes—facing up. After an overhead camera photographs that side, the plate is moved to an area where all marks are erased by scrubbing with an ethanol-water mixture and, if necessary, scraping with a razor blade.

By the time Blumenfeld heard about this process in 2019, more than 400,000 plates had been scanned. “When I learned that they were actually wiping the plates clean of the marks, I was deeply saddened,” she tells me. She set out to preserve the beauty and meaning of the marks, if only on a handful of plates. In honor of the women whose work inspired her own, Blumenfeld calls her art “Tracing Luminaries.”

Blumenfeld’s father says the first word she spoke—standing in her crib, pointing at the fixture overhead—was “light.” Her fascination with light “was there somehow from the beginning,” she says.

That affinity led her to take up photography in high school in the late 1980s and later earn a degree in it from Parsons School of Design. In the years between, Blumenfeld created art inspired by light and ways to capture it. But she draws a distinction: Unlike some artists and photographers, she’s not interested in capturing the way light reflects off landscapes or people. She aims to capture the light itself. 

Starting in the late 1990s, Blumenfeld began building novel lensless cameras uniquely geared to collecting celestial light, from the faint to the squintingly bright. As she made art from the beams of lunar phases, sun cycles, and solstices, Blumenfeld launched what would become continuing engagements with scientific researchers and data.

“I’m always looking for connections,” Blumenfeld says, like the shared traits that she believes connect scientists and artists: an inquisitive nature, strong powers of observation, a gift for thinking deeply about the natural world. She sees those attributes clearly in the words and drawings on the glass plates. “The marks are the material evidence of the women’s passion for and devotion to their research,” she says, and to “the stars themselves.”

Art that would preserve the women computers’ contributions—that’s what Blumenfeld wanted to create. By 2019 she had devised a plan to transfer the marks themselves—the ink laid by the women’s hands—from the plates onto another material. Harvard gave Blumenfeld permission to try that approach with 50 select plates, starting in mid-March 2020. But before the artist could begin, the COVID-19 pandemic forced Harvard to close its facilities to visitors. 

The DASCH project’s in-house work continued: photographing a plate’s hand-inscribed side, wiping it clean, then scanning its astronomical-data side. As the pandemic stretched on, plates that Blumenfeld had hoped to use in her art slipped out of reach. 

Some of the plates with distinctive markings or historical value were permanently secured in a special archive (named the Williamina Fleming Collection, after one of Harvard’s groundbreaking women computers and astronomers). Other plates that Blumenfeld had hoped to protect were run through the scanning process, all of their marks removed. 

Without access to the physical plates, Blumenfeld resorted to working virtually. She spent weeks looking through thousands of plate photographs in the DASCH digital-image portal. Eventually, she chose images of six plates: observations made from 1892 through 1923, including views of both the Small and Large Magellanic Clouds, the Taurus and Pegasus constellations, and Jupiter with its eighth moon.

Blumenfeld shared the digital images of the plates with printmaking collaborators at the design and visual arts school of Washington University in St. Louis. The team mapped a creation process from this first step: “We basically did the inverse of what DASCH did,” Blumenfeld says. “They wiped the marks; I wiped the stars,” so the marks could stand alone.

Based on those marks, each piece took shape through a combination of historical art techniques, new technology, and materials that struck Blumenfeld as the stuff of stars. 

The result: “Tracing Luminaries,” a portfolio of six gold leaf prints. It tells the story of women who studied light to understand the universe, who saw the stars in a way others of their time did not; of a love language to those stars across generations; and an effort to honor that language and those women.

From the beginning, Blumenfeld tells me, “my whole idea was to return their marks to the stars somehow.” She may have, in her way: by bringing those who left the marks—and their discoveries and achievements—out from the shadows into the light.

Liz Kruesi is a science journalist focused on cosmology and astronomy. Her last essay for the magazine was about the Fermi Gamma-ray Space Telescope.

This story appears in the August 2022 issue of National Geographic magazine.

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