Carnegie Science Celebrates Hubble Discovery Centennial
The skies above Los Angeles are more hazy today than they were in October 1923, when Edwin Hubble looked through the eyepiece of the 100-inch Hooker Telescope—at the time the world’s largest observing facility—and changed the course of human history. Light and air pollution have transformed Carnegie Science’s historic Mount Wilson Observatory from the crown jewel of astronomical innovation into a historic, and captivating site for education and outreach in recent decades. But 100 years ago, the mountaintop facility enabled one of the most transformational discoveries in modern astronomy when Hubble discovered Andromeda.
A seasoned astronomer, Hubble was granted the rare opportunity to work on what was then the most advanced telescope technology in the world, conceptualized by George Ellery Hale and funded by Carnegie Science. One wonders what he thought that night, and in the days and weeks that followed, as he employed the mathematical techniques pioneered by Harvard University “computer” Henrietta Swan Leavitt to confirm the distance of a far-away, pulsating Cepheid variable star. If anyone could understand the gravity such a discovery would have on the course of astronomical study, it was Hubble, whom Hale had recruited on the basis of his extraordinary promise. Though the dividends of that investment are now well-known, and the facts of the discovery clear, the only indication we have of Hubble’s emotional reaction to that pivotal moment of revelation is a “VAR!” written in a shaky hand on a cloudy glass plate.
That exclamation point was a harbinger of the long tail and consequences of the discovery. Following its public announcement at the American Astronomical Society’s Annual Meeting in January 1925, it would come to inspire generations to explore the unseen forces beyond our atmosphere, like the dark matter revealed by Carnegie’s Vera Rubin, and the search for planets beyond the Milky Way, pioneered by several Carnegie scientists and alumni. Even for Hubble, it would form the basis of his later revelation that the universe is continually expanding.
For his contributions to astronomy at large, NASA designated Hubble as the namesake of its 1990 space telescope, which has itself captured countless images that have helped to further unravel mysteries of the deep universe and captivated the public imagination. While Hubble’s legacy lives on in that telescope and the data it continues to collect, his reputation was forged on individual, compounding discoveries that are each worthy of celebration in their own right. And in observing the Andromeda discovery centennial, Carnegie Science used that singular occasion to zoom out and explore the past, present, and future of space exploration.
The 16-month celebration kicked off in October 2023 with a VIP reception, educational presentation, and viewing of Hubble’s famous plate in the Observatories’ library in Pasadena. Understanding that Carnegie Science’s long legacy in astronomy continues with field-defining research in Pasadena and at the Las Campanas Observatory in Chile, donors and guests also toured the bespoke instrumentation facilities and learned about current technology employed by our astronomers today.
The next day, President John Mulchaey and Staff Scientist Juna Kollmeier offered a public presentation at the Los Angeles County Museum of Art, a sneak preview of the museum’s Mapping the Infinite: Cosmologies Across Cultures exhibition, for which the Hubble plate was on display from October 2024 to March 2025.
And closing an extraordinary kickoff weekend of events, the Observatories Open House welcomed the public to explore our facilities and see the “VAR!” plate in its home archive. Mulchaey delivered a presentation on the history of the plate and the trajectory of the Andromeda discovery, and Carnegie astronomers were on hand to answer questions about the institution’s work.
The following year brought plenty of opportunities to observe with the anniversary celebration, including the annual Astronomy Lecture Series, an Ode-win Hubble poetry contest, a Hubbleween pumpkin carving contest, and other engagement opportunities across Carnegie’s communications platforms.
And, of course, the LACMA exhibit officially launched and brought thousands of visitors to learn about Hubble’s work and the long line of stargazers of which he is a member. The plate was on view alongside scores of centuries-old artifacts and cultural objects from more than a dozen civilizations, including a floor-to-ceiling projection of video of a survey of galaxies by the Sloan Digital Sky Survey’s fifth generation, of which Kollmeier serves as director, and an image of the Milky Way’s central region captured by a team of scientists including Carnegie Science postdoc Allison Matthews using the MeerKAT radio telescope in South Africa. The exhibition was presented as part of the Getty Foundation’s PST ART: Art & Science Collide initiative.
The celebration culminated at the American Astronomical Society’s Annual Meeting in January 2025 with a reception to honor Hubble and all of the astronomers—including Carnegie staff and alumni—who have built on his work to shape and expand our understanding of the universe. Carnegie Observatories astronomer and Outreach Coordinator Jeffrey Rich made a public statement regarding the centennial of Hubble’s public announcement in a joint press conference with the AAS that featured additional presentations by scientists from NASA’s Jet Propulsion Laboratory, Rhodes College, Duke University, and the University of Arizona. Rich and the other presenters fielded questions from reporters and attending scholars following the presentation. The event garnered media attention from outlets including Space.com and Smithsonian Magazine.
It’s difficult to imagine the last century of astronomy had Hubble not had the tools and facilities made available to him on Mount Wilson. Carnegie Science is inextricable from the revolutionary advancements in science—not only in observational astronomy, but deep-space exploration and planetary science—that have come to shape the United States’ scientific reputation over the past century. We are proud to have been a professional home to Hubble, Hale, Rubin, and so many scientists who have pushed the boundaries of knowledge, and to continue to be so for the scientists who walk boldly in their footsteps and push those boundaries still further.
