The Cosmologist Working to Preserve the Night Sky for the Future

Dr. Aparna Venkatesan studies the distant reaches of space and time, while advocating for a night sky undamaged by orbital clutter.
Image: Michelle Urra
Image: Michelle Urra
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As 2020 draws to a close, Dr. Aparna Venkatesan is struck by how her personal experience of grief—set against a year of collective mourning—has changed something fundamental in her life: the way she looks at the Moon.

Venkatesan, a cosmologist at the University of San Francisco, lost her father in March; a man she described as “my lifelong best friend” and “one of my greatest allies” in a call. 


“I think all girls should have a dad like that,” she said.

With international borders locked down in response to the pandemic, Venkatesan was not able to mourn her father alongside his community in India, where she grew up bouncing from city to city as the only child of enterprising parents. But though the wound is deep, she has found solace in the lunar cycle, which she calls her “grief calendar.”

“My father passed at New Moon,” she said. “As somebody who is a pretty rational scientist, the Moon cycles have become enormously important this year for me. Every time there's a New Moon, it’s like: ‘I'm eight lunar cycles past when I lost this beloved friend; I'm nine lunar cycles past.’ It's become huge.” 

“The Hindu death rites happen monthly in the first year after they pass away—it's a lunar calendar,” she added. “In a way, that's brought me back to my culture.”

For Venkatesan, the human relationship to the Moon—and to the night sky as a whole—is enriched by the cross-cultural diversity of perspectives on the meaning and value of the expanse beyond Earth. Though she is an expert in the otherworldly phenomena of the early universe, an era that is distant in time and space, Venkatesan also wants to protect our collective bond with the skies close to home. 


To the dismay of many astronomers and skywatchers worldwide, the deployment of satellites in mega-constellations, such as SpaceX’s Starlink, creates bright scars across the night sky due to the sunlit glare of the spacecraft. In addition to this light pollution in orbit, the Moon is getting more visitors: NASA hopes to land humans there this decade as part of its Artemis program; China has placed three missions on the lunar surface since 2013, and India and Israel recently attempted Moon landings that ended in crashes.

“By 2025, near-Earth space, the night skies, and the Moon will be permanently altered in my opinion,” Venkatesan said.  

This is profoundly troubling to her not only from a scientific point of view, but because she is an ardent defender of marginalized communities, especially Indigenous peoples, whose astronomical traditions are at risk from busier skies. In an article published in Nature Astronomy last month, Venkatesan and her colleagues propose that we need “a radical shift” towards “the view of space as an ancestral global commons that contains the heritage and future of humanity’s scientific and cultural practices.”

For Venkatesan, the idea of space as an ancestral realm has a special relevance this year, as she looks at the New Moon in a new way. But it is also a natural progression of her fascination with, and respect for, the codes and secrets of the universe, which was sparked in childhood.


“I always loved math, as the universal language,” she said. “I also really loved the night skies, despite growing up in extremely congested, polluted, major cities in the tropics.”

As a teenager, Venkatesan applied to Cornell University to pursue her budding love of space, and remembers the suspense as she waited for the response (her acceptance letter was eventually delivered by telegram). The adjustment to life in small-town New York had some initial rough patches—Venkatesan missed her parents, and wished she’d listened more to her mother’s cooking tips—but she cherished the overall experience and her family’s pride when she became the first woman to receive an undergraduate degree in astronomy at the university. 

“When my father came to my graduation at Cornell, he cried,” Venkatesan recalled. “He was like: ‘Look, I could spend years in these libraries.’ He loved Cornell's libraries. I had very encouraging parents and I really commend them, given what a conservative society we are.”

Under the guidance of her advisor Steve Squyres, a prolific planetary scientist, Venkatesan spent much of that first degree combing through observations of Venus taken by NASA’s Magellan orbiter, which studied the planet from 1989 to 1994. The work was thrilling, as sometimes she would be the first human ever to behold a part of Venus as new data flowed in on her overnight shifts. 


When she arrived at the University of Chicago as a graduate student, she shifted gears to focus on big cosmological questions: When were the first stars born? What is dark matter? What is the precise source of all the elements? 

“I was eager to work in cosmology because I had gone to Cornell to do that, but ended up, you know, working on literally the nearest planet,” Venkatesan said. “It was time to go back to the other end of the universe.”  

With the help of dedicated mentors like astronomer Jim Truran, who she said taught her an “integrative approach” to cosmology, she learned to appreciate the whole spectrum of evidence about our cosmic origins, from the light of long-dead stars to the elements that make up our bodies.

“There are some lovely puzzles in lithium, calcium, carbon, and titanium that we don't understand, when we look at the element abundances in the oldest stars in our galaxy, or even just in galaxies,” Venkatesan said. 

“Look, I'm never going to get tired of looking at ancient light,” she continued. “It is a visceral thrill to say: ‘Oh, my God, when light left this galaxy, cyanobacteria hadn't even begun on Earth or the oceans, or maybe the Earth wasn't even around.’ I'm never gonna get tired of that. But the elements are here, in a very real way. We are the evidence.”


After earning her PhD in Chicago, Venkatesan served as a research associate at the University of Colorado, Boulder, for a few years, before becoming the first female professor of physics at the University of San Francisco. Since 2012, she has also participated in the Arecibo Legacy Fast ALFA (ALFALFA) collaboration, which involved accompanying students to study at Puerto Rico’s Arecibo Observatory. 


Venkatesan under Arecibo’s dish. Image: Aparna Venkatesan

Like so many people who loved Arecibo, Venkatesan was heartbroken when it collapsed earlier this month after multiple cable malfunctions. She has countless fond memories of the iconic observatory: celebrating the 21st birthday of a student during an observation shift, listening to nocturnal frog calls in the dense misty foliage under the dish, or watching the Southern Cross constellation illuminate the Caribbean skies in the crepuscular hours before dawn.

“The science of working there is just unparalleled and I loved the people of Puerto Rico, both the observatory staff and the people beyond the observatory,” Venkatesan said. “I also really loved the scientists who live there year round. I mean, these people were on-the-ground geniuses: they could listen to the hum of the telescope and tell you which panel or receiver was off.”

“All observatories have this magical mystical side to them—you can't help but feel it, being out under this glowing sky, taking data—but Arecibo had it more than most,” she added.


For Venkatesan, Arecibo is one of many beloved elders that we lost this year. As a busy mother of two teenagers, she is juggling new school and work challenges like so many during the pandemic, but she has managed to find moments to work through the grief by remembering loved ones lost, and cherishing those who remain.

During our call, she talks about many of her mentors and inspirations over the years, heaping praise and gratitude on these bright stars in a dark night. The list includes her parents, her professors, the Moon, Arecibo, and the redwood forests of California.

But an elder that sticks out in particular, at the nadir of 2020, is blues musician Blind Willie Johnson, who suffered racism, poverty, and illness until his death in 1945. Venkatesan has an eclectic musical taste and a passion for singing across genres, but she is particularly keen on Johnson, whose haunting voice reverberates with the transcendent sorrow that shaped his life. 

As she often tells her students, Johnson’s song “Dark Was the Night” is on the Voyager Golden Record, a repository of sounds and images from Earth carried by NASA’s twin Voyager probes, which have passed into interstellar space. On this Monday, the winter solstice and the darkest day of a harrowing year, the song has special resonance.

“The blues is so beautiful,” Venkatesan said, “it's actually left the solar system.”