This article is part of the “Building from Diversity” project.
Sandra Faber: A Luminous and Inspiring Scientific Career
Written by Nicole Araneda, PhD Student at the Universidad Autónoma de Madrid (Spain)
In the world of science, figures like Galileo, Newton and Einstein tend to dominate the spotlight, but many other notable figures have contributed significantly to our understanding of the cosmos. One of them is American scientist, Sandra Faber.
Her life and career are a testament to her dedication, curiosity and persistence. Through her passion for science, she has left a permanent mark on the exploration of the Universe, and her brilliant legacy lights the path for future generations.
Sandra Moore Faber was born in Boston, Massachusetts on December 28, 1944 . From an early age, her interest in science and astronomy grew despite the low representation of women in this discipline in the 60s. Her deep interest in this subject led her to become one of the most prominent figures of contemporary astronomy.
Sandra completed her bachelor’s degree in Astronomy at Swarthmore College in 1966 and subsequently earned her Ph.D. at Harvard University in 1972 , specializing in Optical Observational Astronomy under the direction of I. John Danziger . That same year, she joined the faculty at the Lick Observatory at the University of California, Santa Cruz, becoming the first woman to serve on the staff. Her research focused on using the lookback power of large telescopes to study the formation and evolution of galaxies .
In 1976, one of Sandra’s investigations, which consisted of observing the relationship between the brightness and spectra of galaxies and the orbital velocities and movements of the stars within them, resulted in the discovery of the Faber-Jackson relationship. This relationship assumes a direct connection between the galaxy’s brightness and its stars’ dispersion speed . This means that if we know the dispersion speed of stars in a galaxy, we can estimate their luminosity. The Faber-Jackson relationship is essential in astronomy since it allows us to measure the masses of galaxies more precisely. By knowing how massive galaxies are, we can better understand how they formed and evolved.
In 1979, Faber and John S. Gallagher published a paper that presented a review of the evidence for the existence of dark matter . This paper is regarded among astronomers as the turning point in the quest to determine whether 80 percent of the mass in the Universe is “missing”—mysterious, invisible and impervious to direct detection. This discovery of large amounts of dark matter (using indirect methods of detection) in a certain exotic species of galaxy led Sandra to conclude, in a paper of 1983 with UCSC astronomer Douglas Lin, that dark matter could not be neutrinos, subatomic particles that travels close to the speed of light (“hot,” in cosmological terms), but might be another species of subatomic particle, not yet known, that travels at a much slower rate (“cold”) .
On the other hand, Sandra played a fundamental role in large-scale projects, such as her contribution to installing the Keck Observatory in Hawaii, one of the biggest optical telescopes in the world. Her involvement in projects with the Keck telescope includes research on galaxy dynamics, the detection of supermassive black holes and the evolution of galaxy clusters.
Additionally, she is recognized in her field for her contributions to the design and use of large telescopes. For example, Sandra was part of the design team for the Hubble Space Telescope’s Wide-Field Camera  and is the principal investigator of the DEIMOS (Deep-Imaging Multiobject Spectrograph) project . She was also the co-principal investigator of the CANDELS Research Team , which used the Hubble Space Telescope to investigate galaxies in their initial stages of formation.
As a result of her outstanding academic and professional career, Sandra has received numerous awards and recognitions, including the U.S. National Medal of Science (2013) , the Gruber Prize in Cosmology (2017)  and the Gold Medal of the Royal Astronomical Society of the UK (2020) .
And Sandra has transmitted her wisdom and experience through teaching, too. She has been a professor at the University of California at Santa Cruz, teaching core subjects and guiding students in her research. She also holds the title of Professor Emerita at this university , where she has left an indelible mark on the academic and scientific community.
Sandra Faber’s legacy transcends her gender and inspires us all, regardless of our circumstances or obstacles. Her story reminds us that with passion, perseverance and commitment we can reach for the stars, both figuratively and literally. Her life is a powerful reminder that there are no limits that cannot be overcome in the search for knowledge. Science is a world of infinite possibilities, and anyone can be part of it, contributing to expanding our understanding of the Universe.
Article reviewed by Viviana Gammaldi, researcher at the Universidad Autónoma de Madrid (Spain).