When astronomer Vera C. Rubin was growing up, she built her own telescope to watch the night sky from her bedroom in Washington, D.C. After being rejected from Princeton for graduate school (where women were prohibited until 1973), she was accepted at Cornell and later began studying how galaxies in the night sky change over time. Her research throughout the 1970s uncovered a mystery about the universe that scientists are still trying to fully understand today.
In collaboration with Kent Ford, Rubin’s calculations are generally seen as the first substantial evidence supporting the idea that dark matter actually comprises the majority of the universe’s mass. Today, the National Science Foundation and the Department of Energy are honoring Rubin for her work by naming a new observatory in Chile after her.
Rubin’s calculations are generally seen as the first substantial evidence supporting the idea that dark matter actually comprises the majority of the universe’s mass.
As the first observatory named after a woman, the Vera Rubin Observatory will provide the most detailed map of the universe in history. While telescopes like Hubble and James Webb can zero in on specific regions of space to get high-quality images of particular galaxies, the Rubin Observatory instead casts a wide net, taking continuous snapshots of the entire visible night sky. Its Legacy Survey of Space and Time will measure the sky every three days over the course of a decade to create a slow-motion movie of observable changes in the universe.
“You can think of it as a Google for the sky,” says Mario Juric, Ph.D., an astronomer at the University of Washington and the principal investigator of UW's contribution to the Rubin Observatory. “It downloads everything that's in the sky and then organizes that into a nice searchable index to offer to astronomers.”
In partnership with thousands of astronomers across the globe, the observatory has the potential to help us better understand dark matter and dark energy, detect asteroids with the potential to crash into Earth and answer other astronomical questions that have tantalized scientists for decades. Most of the data it captures will also be publicly available for scientists and amateur astronomers alike within 60 seconds of its capture, said Melissa Graham, Ph.D., a UW astronomer and the Rubin Observatory’s Head of the Community Science Team.
“To me, it is important that this observatory is named after [Rubin] not only because the data will enable advances in understanding the dark matter she proved existed, but because it represents contributions of women to astronomy and our higher goals of research inclusion: providing a cutting-edge astronomical data set that is accessible to all,” Graham told Salon in an email.
Salon spoke with some of the scientists involved with the Rubin Observatory during its construction over the past two decades to get a better sense of what to expect from the observatory. Here are four big astronomical questions it could help explain when it goes online in 2025.
With the technology currently available, astronomers are constantly discovering new objects in the night sky, anything the size of a few feet across to objects as large as Pluto. Since the first asteroid was discovered 200 years ago, about 1.2 million asteroids at least one kilometer in diameter have been identified. The Rubin Observatory's massive scope is projected to nearly double that within the first three to six months after it opens, ultimately increasing the number of these objects we know about in the night sky to around five million by the end of its survey, Juric said. Asteroids detected by the observatory can provide clues into how the planets in our solar system formed and changed over time, he explained.
“If you think of the solar system as a big construction yard, these asteroids are like rubble that's left over after construction is finished,” Juric told Salon in a phone interview. “You can sort of walk through a construction yard and figure out what's been going on by where all the rubble wound up — or where the tools are.”
Although most new asteroids will probably be discovered in the main asteroid belt between Mars and Jupiter, Vera Rubin will also be able to detect “near-Earth asteroids” that have the potential to strike the planet, said Zeljko Ivezic, Ph.D., a UW astronomer and director of Rubin Observatory Construction.
“In order to rule out the possibility that they are dangerous, you need to observe them at least half a dozen times so that you can calculate their orbits,” Ivezic told Salon in a phone interview. “Then you can answer the question: Are they over the next few centuries going to pose any threat to Earth?”
When a star explodes in a supernova, it can release the same amount of light as one billion stars emit at once, making a single point in the sky where the explosion takes place as bright as an entire galaxy, Graham said. Because these supernovae take place light years away, it’s very rare to detect which star in a cluster is the one exploding, she explained.
Some supernovae can last 10 days, while others last months, with all sorts of changes in color and light throughout the process, Graham explained. The Rubin Observatory, which will host the largest digital camera in the world, will be able to detect changes in light during supernovae that help explain what provokes them and, in some cases such as with carbon-oxygen white dwarfs, whether they might happen because two stars are colliding, Graham said.
“By finding millions of supernovae with the Rubin Observatory and the LSST, we will be able to test theories like this for all kinds of exploding stars,” Graham said. “Understanding supernovae is important, in part because they release the heavy elements fused in stellar interiors [and] these elements go on to form metal-enriched objects like our own planet Earth.”
It has been proposed that dark matter and dark energy — the latter of which causes the universe’s expansion to speed up — together make up about 96% of the universe, with all of the matter and energy we encounter in our everyday lives making up the remaining 4%. This work builds on Rubin’s original calculations in the 1990s, which some have argued should have earned her the Nobel Prize.
Because dark energy is invisible — and no one is entirely sure what it is — scientists have to instead look to objects in space that are affected by it as clues that help explain its behavior. One of the main sources of evidence used to prove the existence of dark energy is supernovae. When a star explodes, scientists use the way its light ripples out to space to measure distances and calculate the expansion of the universe.
However, one controversial 2020 study found fluctuations in the brightness of supernovae, which cast doubt on whether they could be used to measure the expansion of the universe and put into question whether dark energy even exists. By measuring distortions of light across billions of galaxies, the Rubin Observatory has the potential to get to the bottom of this question that scientists have been disputing for the past decade.
“The ultimate result that we want to get is to see if there is really something that is dark energy that explains the accelerated expansion of the universe,” Ivezic said.
In 2017, a telescope in Hawaii detected Oumuamua, the first of two interstellar objects to ever enter our solar system. While the origins of Oumuamua have been debated because it lacked any sort of tail that a normal comet would have — with some suggesting it was a spacecraft but more likely evidence suggesting it was indeed a comet — another interstellar object detected in 2019, 2I/Borisov, did have a comet’s signature tail trailing behind it.
Scientists have long thought more interstellar objects are out there, and the Rubin Observatory is expected to find anywhere between one additional object per year or even one per month, Juric said. In the next decade, the European Space Agency (ESA) is also planning to launch its Comet Interceptor mission, which can be deployed to take photos of what these interstellar objects look like up close. Through the observatory, the mission will likely be able to detect many such objects that would otherwise be missed, Juric explained.
“We just don't know what's out there and that's what makes it so interesting,” he said. “This will tell us immediately how many of these things are floating through space.”
The thought echoes what Rubin herself once said when asked whether dark matter does indeed exist: "We know so little about our universe," she said. "It is a strange and mysterious universe. But that’s fun.”
Shares