Vera Rubin was the GOAT of dark matter
How the pioneering scientist, and namesake of an enormous new telescope, forced astronomers to rethink the universe. Astronomer Vera Rubin spent much of her career at the Carnegie Institution's Department of Terrestrial Magnetism in Washington, D.C. She's best known for convincing the world that dark matter exists. Photograph by Richard Nowitz, Nat Geo Image Collection
Vera Rubin had just finished her ice cream when she saw something that would change astronomy forever. It was long past midnight one early morning in the 1960s, and Rubin and her colleague Kent Ford were at Kitt Peak National Observatory in the middle of the Arizona desert. That night they were tracking how hot gas from young stars circled Andromeda, the Milky Way's galactic neighbor. Rubin and Ford would trade off recording the gases' chemical fingerprints or processing photographic plates. While waiting for the plates to develop, Rubin would eat an ice cream cone.
Four cones in, Rubin could draw Andromeda's rotation curve—she could plot the distance of gas clouds on an X-axis and their speeds on the Y-axis. At the time, astronomers assumed the stars circling a galaxy would act like the planets circling the sun in our solar system. Stars closer to the galaxy's center would circle quickly, while stars farther out would orbit slowly because core's gravitational pull was weaker out there. The curve, then, should start high and fall the farther the distance from a galaxy's center, astronomers assumed.
Rubin never liked assumptions. She'd rather collect data, even if it met expectations. But what Rubin saw in that rotation curve didn't. The close-in and far-out stars seemed to be circling Andromeda at roughly the same speeds. The curve was flat.
The ice-cream fueled find, and those that followed, forced astronomers to rethink not only what we know about galaxies but also what we know about the universe. It forced them to reimagine the fabric of the cosmos. They'd ultimately conclude that that fabric included a mysterious substance, an invisible form of matter now known as dark matter, that to this day we don't fully understand.
But it wasn't just this Copernican-esque discovery of flat rotation curves that made Rubin a legend. It was the way she discovered it, the way she advocated for equality in astronomy, the way she welcomed new astronomers into the field without hesitation and kept going to the telescope well into her eighties, which is when I got to know her.
It was November 2007 when I joined Rubin at Kitt Peak. No photographic plates. No winter ice cream. Just a veteran astronomer, a cub reporter, and a spiral galaxy to observe. It was in her reminiscing during those nights that I came to understand that her dark matter discovery story wasn't one of a cliché lone genius and a eureka moment. Her observations were a fold in the braid that led to dark matter becoming astronomy dogma. And, her decades of discoveries were only part of her legacy, with her outspokenness and moral compass cementing it to memory. It's this layered legacy I see in the new Vera Rubin Observatory, which will deliver its first images this month.
(A century ago, this pioneering astronomer discovered what stars are made of.) The immense Andromeda galaxy, also known as Messier 31, is captured in this NASA image. Rubin's observations of Andromeda would change our understanding of the universe. Photograph by NASA/JPL-Caltech/UCLA
Eleven-year-old Vera Rubin—Vera Cooper, then—stared at an imaginary line running down the bed she shared with her sister, Ruth, then rolled over, defeated. She was the younger of the two and was told she couldn't sleep next to the small row of windows that lined the inner wall of the bedroom and fortuitously faced north in their rented townhouse in Washington, D.C. But even from the inside edge, the starlight caught Vera's attention; she was mesmerized. Every night, she'd crawl over her sister Ruth to get a better view of the sky. 'There was just nothing as interesting in my life,' Rubin once said, 'as watching the stars.'
Through her childhood in the 1930s, she would hang out by the window tracing star trails, check out library books about scientists, and build her first telescope with her dad, who worked for the Department of Agriculture. He'd also take her to the local amateur astronomy club where she heard talks by astronomers like Harlow Shapley, then the director of the Harvard Observatory.
By the time Vera was in high school, she sought out cosmology books like James Jean's The Universe Around Us and Arthur Eddington's The Internal Constitution of Stars. At Vassar College, she majored in astronomy, taught herself how to observe using the college's telescopes, and took summer positions at the Naval Research Laboratory to gain experience doing science experiments. Around then, her parents introduced her to Robert Rubin. They began dating and were married in August of 1948—what many assumed was the end to Rubin's astronomy career.
Vera had gotten accepted to Harvard for her master's degree. But she chose to go to Cornell University, where Bob was working on his Ph.D. in physical chemistry, instead. There were roadblocks, but Rubin found mentors in physicist Richard Feynman and astronomer Martha Star Carpenter, and her husband, who helped her launch a research project see if the universe rotated—all while they started a family. When she presented her results at the 1950 American Astronomical Society meeting in Ithaca, New York, the press was sensational. 'A young mother startled the American Astronomical Society,' the Associated Press reporter wrote. Her work challenged convention, and she would again while working on her Ph.D. at Georgetown University. Vera Rubin (pictured in 1965) and her observing partner Kent Ford also used telescopes at the Lowell Observatory in Flagstaff, AZ, to study the rotation curves of galaxies. Photograph by The Washington Times/ZUMA Press/Alamy Stock Photo
Despite her research, Rubin often felt like an imposter. She earned her Ph.D. in 1954, and about a year later, took a faculty position at Georgetown. She and Bob were growing their family then, and for the next few years, she took on a variety of research projects, always analyzing others' data. Even then an imposter in her own mind, she'd advocate for her students, threatening to pull a paper from publication because the journal wouldn't print the names of the students who worked on it, for example. But, after nearly a decade, Rubin grew tired of relying on others' work to do her own.
Finally, she got a break. Observational astronomers Margaret and Geoffrey Burbidge, famous for their paper on the origin of chemical elements in the life and death of stars, invited Rubin to work with them. They were also interested in galaxies and taught her the technique to calculate stars' and gas clouds' speeds. A first taste of being a real astronomer, she said. Shortly after, Rubin knew she needed access to a telescope. She went to the Department of Terrestrial Magnetism, part of the Carnegie Science Institution and talked with radio astronomers there. Then, she asked for a job. She moved into Kent Ford's office on April Fool's Day in 1965 and never left.
A few years later, she and Ford discovered Andromeda's flat rotation curve. Then flat curves in other galaxies. By the early seventies, Princeton theorists Jeremiah Ostriker and Jim Peebles were running computer simulations of galaxies to figure how to get the galaxies to stay together in dizzying spirals like Andromeda. Only when the duo enveloped particles representing galaxies in spherical halos in their simulations would the galaxies cease to fly apart. They needed some extra mass to hold them together.
Observations and simulations combined, astronomers knew they needed to rethink how the universe worked, and slowly the idea of dark matter took hold. By the early 1980s, consensus emerged: Dark matter existed, most conceded.
(How will the universe end? The answer might surprise you.)
While this shift was happening, Rubin was pushing for another—equality in astronomy. She worked on an American Astronomical Society report that highlighted issues such as discrimination in hiring, both "blatant or not", a pay gap between men and women with the same qualifications, and lower pay for married women. And, of course, she placed a cutout of a woman on the door of the historic men's-only bathroom at Palomar Observatory in California.
Younger astronomers looked up to Rubin, appreciating her candor on sexism and having it all—career, family, and a loving relationship. 'For many of us, Vera had a personal impact. She demonstrated that a woman who was as cheerful, warm, generous, and down-to-earth as she was could be a successful astronomer,' astronomer Deirdre Hunter wrote not long after Rubin's death in 2016. She fostered a sense of belonging, one I felt too.
It's how I, at 22, found myself at Kitt Peak with Rubin, on her final time observing, absorbing her life lessons on her grace, wit and grit. She was humble and a deep thinker. Many say she deserved a Nobel Prize. She questioned if she wanted it. 'It changed your life,' she said, and 'not always in a good way.' While studying her galaxy, I sensed of battle of wills, the tug of homelife and professional life. Her husband was ill and her childhood wonder of the universe unfulfilled.
Rubin's wonder lives on in the observatory that will bear her name. It will challenge our assumptions just as she did, and I hope it will remind us that her legacy is more than a telescope. It is a blueprint for humanity—to be curious, never assume, and above all be kind.
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a day ago
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Vera C. Rubin debut images: How to see the groundbreaking space photos from the world's largest camera
When you buy through links on our articles, Future and its syndication partners may earn a commission. The new Vera C. Rubin Observatory is set to release its debut images — taken with the largest digital camera ever built — on Monday (Jun. 23). The world-first images and videos will be ultra-high-definition and will show off the observatory's highly anticipated, cutting-edge capabilities for the first time. Here's what you need to know. If you want to watch from home, a news conference will be streaming on YouTube in English and Spanish at 11:00 a.m. EDT on Monday. The link to watch is posted on the observatory's website, and is also embedded here. If you'd prefer to bask in the awe of the cosmos with friends, you may be able to attend a watch party near you — or even host one of your own. Groups will gather across the globe in planetariums and universities to admire the highly detailed images and videos as they are released. The observatory has shared links to a map of all registered watch parties, as well as a link to sign up to become a host. During the news conference, the observatory team will introduce the Rubin Observatory before showcasing the new images and discussing their significance. Watch parties may also hear from local scientists and special guests. Be sure to check out the details of a watch party before you attend to learn about any extra programming. The observatory, perched high on a mountain in the Chilean Andes, will peer at interstellar comets and dangerous asteroids, as well as larger objects, like twisting galaxies and exploding supernovas. Related: 'People thought this couldn't be done': Scientists observe light of 'cosmic dawn' with a telescope on Earth for the first time ever Inside Rubin lies the world's largest digital camera and six of the largest optical filters ever produced. Together, they allow researchers to observe different facets of the universe in many wavelengths of light and remarkably high detail. The camera will take a new high-resolution photo of the sky around every 40 seconds. The images will then be transmitted via fiber optic cables to a supercomputer in California, which will analyze the photos. When stitched together, the images can act as a time-lapse video of space, one that is planned to span 10 years. RELATED STORIES —Space photo of the week: Observatory, or alien planet? Boggle your mind with this 360-degree image —Vera C. Rubin Observatory: The groundbreaking mission to make a 10-year, time-lapse movie of the universe —3,200-megapixel camera of the future Vera Rubin Observatory snaps record-breaking 1st photos Using its groundbreaking instruments, the observatory is expected to contribute to current understanding of widely debated phenomena, including dark energy and dark matter — two components that are thought to make up a vast majority of the universe, but remain poorly understood. The new images could be the first of many that vastly improve our understanding of the cosmos. Whether you join a watch party or tune in from the comfort of your couch, these photos are not to be missed.
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The 4 biggest mysteries the new Vera Rubin Observatory could solve
On a mountaintop in Chile's sprawling Atacama Desert, a new telescope has turned its mechanical eyes to the heavens, stargazing with unprecedented intensity. The Vera C. Rubin Observatory will take hundreds of pictures, every night, for the next 10 years. Astronomers around the world are absolutely giddy over Rubin, which is named for the late astronomer who discovered evidence for the existence of dark matter. The observatory's mirrors will collect a tremendous amount of light, catching the glint of very faint, faraway objects. That light will be focused into the largest digital camera on the planet, a 3,200-megapixel camera the size of an SUV, capable of producing pictures from multiple wavelengths of light. Instead of focusing on one segment of sky for hours at a time, Rubin is designed to take in a wide field of view, swiveling every five seconds to stare at a new spot with minimal shakiness. Stitched together, the observations will produce unprecedented time-lapse views of the entire night sky from the Southern Hemisphere, revealing a lively universe. (Vera Rubin was the GOAT of dark matter) Rubin is scheduled to begin full operations later this year, after technicians complete some final testing. So where does one point a half-billion dollar telescope? Scientists predict that the observatory will discover millions of asteroids and comets, several million supernova, 17 billion stars in the Milky Way, 20 billion galaxies, and other astrophysical phenomena that may have never been detected before. Our cosmic cup runneth over. Other observatories, on the ground and in space, have granted us countless cosmic wonders, but no telescope has basked in the night sky quite like this before. One might wonder whether 10 million exploding stars is perhaps too many, and indeed, astronomers I spoke with about Rubin say they're a tad overwhelmed. "A hundred years ago, you went to the telescope, you took your data, maybe on a photographic plate, and you brought it home and locked it in your desk drawer," Pauline Barmby, an astronomer at Western University in Canada, says. There will be so much data "that we really have to come up with much different ways of analyzing it," Barmby says. Scientists are ready to sift through the observations, which could help solve some of astronomy's biggest mysteries, from the workings of the solar systems to the large-scale forces driving the future of the universe. Here are the four biggest mysteries the panoramic observatory will investigate. For the last decade, astronomers have pondered about a mystery that stands to completely rewrite science textbooks: Is there actually another planet in our solar system, something the size of Neptune, drifting in the darkness? Scientists refer to this hypothetical world as Planet Nine, and Rubin may settle the matter of its existence. (Pluto, you might have heard, no longer holds the title of the ninth planet in the solar system, having been reclassified, on the grounds of various astronomical definitions, as a dwarf planet in 2006.) The theory for Planet Nine arose out of observations of icy celestial bodies that orbit beyond Neptune, in a region called the Kuiper belt. A handful of these objects seem to be tracing unexpected orbits through space; something other than the sun's gravity appears to be influencing their movements. One explanation is the presence of a giant, unseen planet, exerting enough gravity to mold their orbital journeys. There are other explanations that could explain the strange orbits, from the extravagant (perhaps there's a tiny black hole out there, or evidence for a new theory of gravity), to the more mundane (maybe there's nothing odd about the orbits, and our picture of the Kuiper belt is just incomplete.) Existing telescopes aren't capable of spotting the faint glow of such a faraway maybe-planet. But Rubin may find Planet Nine within the first year or two operations, says Megan Schwamb, an astronomer at Queen's University, Belfast, in Northern Ireland. Scientists have worked out a search area in the night sky. If the planet is there, "we'll see it like we see Pluto," Schwamb says—a bright pinprick in the inky shadows of the Kuiper belt, reflecting the light of its star. If there's no grand X-marks-the-spot moment for Planet Nine, "that doesn't mean it's not there," Samantha Lawler, an astronomer at Campion College in Canada, says. "It could just be farther out, or it could be smaller or less reflective." Astronomers will need to keep scrutinizing the behavior of trans-Neptunian objects, and Rubin is poised to discover 37,000 trans-Neptunian objects, expanding the current catalog tenfold. In a sea of these newly found celestial bodies, convincing evidence of Planet Nine may float to the surface, or become washed away altogether. While Schwamb and Lawler would be delighted to welcome a new planet, they're thrilled at the prospect of learning more about the realm beyond Neptune, which is intriguing in its own right. The frozen objects in the Kuiper belt are remnants of the formation of our cosmic neighborhood, like eraser shavings brushed off to the side of the page, and astronomers can study them to better understand its bygone eras. "I have no doubt there will be other weird patterns that we see in those orbits that will lead to other interesting ideas about what may or may not be in our solar system now, and how it has changed over time," Lawler says. In 2017, a ground-based telescope in Hawaii caught an unusual object hurtling through the solar system, untethered from the gravity of the sun. Oumuamua, as the object was later named, left astronomers with many questions about a previously undiscovered cosmic population, and some wild conjectures about alien origins that are still floating around today. A second surprise object, named Borisov, showed up in 2019, further deepening the mystery. Rubin will provide many more opportunities to study these interstellar objects, which can coast through the galactic hinterlands for hundreds of millions of years before encountering the warmth of a star. These objects appear without warning, and move fast, so they can be difficult to catch—unless you're constantly making time lapses of the night sky. Interstellar objects are believed to be ejected from their home systems during planet formation, a notoriously turbulent time. (Bits of our own solar system, hurled away several billions of years ago, are likely floating somewhere in the galaxy.) 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"If we find very few [interstellar objects], I think we might have to rethink what sort of planetary systems exist in the galaxy," Lintott says. Even with the powerful new observatory, astronomers likely won't be able to trace interstellar objects to their exact starting points "because they've been mixed around the galaxy so much," says Michele Bannister, a planetary astronomer at the University of Canterbury in New Zealand. But they can analyze their chemical composition to glean information about their home star, including its age. Scientists may even be able to determine if two or more interstellar objects originated from the same cluster of stars. And they can use Rubin's future catalog to test various theories, including whether entire corridors of these interstellar objects exist, winding through the galaxy like ribbons. Even a small sample of them "tells us so much about these processes happening across our whole wonderful, wide galaxy," Bannister says. Galaxies form in a messy process, says Barmby, the Western University astronomer. "There's gas falling in, there's gas getting blown out, there's stars forming, there's stars dying, and all of that stuff happens on super-long timescales that we can't actually watch happen." Sometimes, in the process, stars in one galaxy get taken up by the gravitational force of another. These are known as stellar streams, and the new observatory is expected to reveal many more of these in our own Milky Way, hovering like bees around the shimmering rose of the galaxy. Rubin's observations will allow astronomers to track the motions of individual stars over long periods of time, which can reveal whether they originated inside the Milky Way or came tumbling in from a nearby galaxy. Rubin is also expected to discover more of the small galaxies that orbit the Milky Way, which have unwillingly donated some of those stars. Each galaxy has its own fascinating cosmic personality; one of the smallest has just a few hundred stars, compared to the Milky Way's 10 billion, says Yao-Yuan Mao, an astrophysicist at the University of Utah. He expects that Rubin will discover all the little galaxies that can possibly be observed, not counting those that are situated behind the bright disk of the Milky Way, which will remain forever out of view from Earth's perspective. "We will get a super complete picture of our Milky Way system," Mao says. And by comparing our galaxy system with that of others, astronomers can tackle one of the most animating questions in the field: whether the way the cosmos works here, in our part of it, is the same as everywhere else. "The knowledge that we inferred from studying the Milky Way—is that generally applicable across the universe?" Mao says. "Or is there something special or unique about the Milky Way itself?" As Rubin captures pictures of millions of cosmic objects, the observatory will also be searching for signs of two completely invisible things: dark matter and dark energy. All of the stars, galaxies, gas—all of the matter we can observe—turns out to be just 5 percent of "the total stuff in the universe," says Alex Drlica-Wagner, an astrophysicist at the University of Chicago. The rest is dark matter, a kind of matter that doesn't emit or absorb light, which accounts for 25 percent of the universe's composition, and dark energy, a phantom entity that makes up 70 percent. While scientists have never directly observed either, they've seen the cosmos behaving in certain ways that suggest they must exist. Rubin won't reveal all of their secrets, but the sheer amount of data will serve as a veritable playground for scientists to test their theories about these phenomena. Astronomers first suspected the existence of dark matter in the 1930s when they noticed that some galaxies remained clustered together even though they were traveling fast enough to fly apart, suggesting that another force was keeping the galactic web intact. In the 1970s, Rubin's namesake astronomer discovered a similar effect at the edges of galaxies, where whizzing stars that should have escaped were instead being held tight. The mark of the unseen material can even be found using starlight itself. Dark matter can bend light as it passes by, making its source—a distant galaxy, for example—appear distorted. Rubin will collect these warped views, allowing astronomers to "map out where the dark matter is by how we see the light bending as it travels to us," Drlica-Wagner says. Those maps can help illuminate the nature of dark-matter particles, including whether they're cold or hot—seemingly small characteristics with the capacity to reshape our understanding of how the universe assembles galaxies. Dark energy is even more mysterious. The idea emerged in the 1990s, when astrophysicists calculated that the universe was expanding faster over time rather than slowing down, which ran counter to laws of physics that governed the rest of the cosmos. Dark energy was determined to be the driving force, although scientists don't know what it actually is, only that it appears to behave differently than anything else in the universe, Drlica-Wagner says. Unlike dark matter, which, like the regular cosmic stuff, is likely made up of some kind of particles, dark energy stretches the very fabric of space, pushing galaxies apart rather than drawing them together. Rubin's massive catalog of exploding stars will come in handy here: Scientists can use certain kinds of supernovas to trace the universe's expansion, and, in turn, dark energy's role in it. Rubin data could confirm or refute new theories that suggest dark energy is changing over time, rather than remaining constant, upending even Einstein's predictions for this perplexing force. In the end, the most exciting discoveries Rubin makes might be the ones astronomers haven't yet anticipated. Such is the nature of really good new telescopes: the thrill of what we don't know we don't know. "If someone says, I have never seen a six-foot-tall-rabbit, you can say, sure, how hard have you looked?" Michael Wood-Vasey, an astronomer at the University of Pittsburgh who has spent years helping to prepare the Rubin observatory for operations, says. Perhaps the new observatory, with its constant, scouring gaze, will turn up some cosmic rabbits.
National Geographic
2 days ago
- National Geographic
The 4 biggest mysteries the new Vera Rubin Observatory could solve
No telescope has basked in the night sky quite like this before. Here's what it could reveal about the universe. Vera Rubin Observatory, its dome reflecting the last sunlight at sunset in Chile. May 30, 2025. Photographs by Tomás Munita On a mountaintop in Chile's sprawling Atacama Desert, a new telescope has turned its mechanical eyes to the heavens, stargazing with unprecedented intensity. The Vera C. Rubin Observatory will take hundreds of pictures, every night, for the next 10 years. Astronomers around the world are absolutely giddy over Rubin, which is named for the late astronomer who discovered evidence for the existence of dark matter . The observatory's mirrors will collect a tremendous amount of light, catching the glint of very faint, faraway objects. That light will be focused into the largest digital camera on the planet, a 3,200-megapixel camera the size of an SUV, capable of producing pictures from multiple wavelengths of light. Instead of focusing on one segment of sky for hours at a time, Rubin is designed to take in a wide field of view, swiveling every five seconds to stare at a new spot with minimal shakiness. Stitched together, the observations will produce unprecedented time-lapse views of the entire night sky from the Southern Hemisphere, revealing a lively universe. The Vera Rubin Observatory will offer an unprecedented view of the universe's wonders. Chile's new Vera Rubin Observatory, May 31, 2025. Rubin is scheduled to begin full operations later this year, after technicians complete some final testing. So where does one point a half-billion dollar telescope? Scientists predict that the observatory will discover millions of asteroids and comets, several million supernova, 17 billion stars in the Milky Way, 20 billion galaxies, and other astrophysical phenomena that may have never been detected before. Our cosmic cup runneth over. Other observatories, on the ground and in space, have granted us countless cosmic wonders, but no telescope has basked in the night sky quite like this before. One might wonder whether 10 million exploding stars is perhaps too many, and indeed, astronomers I spoke with about Rubin say they're a tad overwhelmed. "A hundred years ago, you went to the telescope, you took your data, maybe on a photographic plate, and you brought it home and locked it in your desk drawer," Pauline Barmby, an astronomer at Western University in Canada, says. There will be so much data "that we really have to come up with much different ways of analyzing it," Barmby says. Scientists are ready to sift through the observations, which could help solve some of astronomy's biggest mysteries, from the workings of the solar systems to the large-scale forces driving the future of the universe. Here are the four biggest mysteries the panoramic observatory will investigate. The Milky Way is seen above the observatory's Simonyi Survey Telescope. For the last decade, astronomers have pondered about a mystery that stands to completely rewrite science textbooks: Is there actually another planet in our solar system, something the size of Neptune, drifting in the darkness? Scientists refer to this hypothetical world as Planet Nine , and Rubin may settle the matter of its existence. (Pluto, you might have heard , no longer holds the title of the ninth planet in the solar system, having been reclassified, on the grounds of various astronomical definitions, as a dwarf planet in 2006.) The theory for Planet Nine arose out of observations of icy celestial bodies that orbit beyond Neptune, in a region called the Kuiper belt. A handful of these objects seem to be tracing unexpected orbits through space; something other than the sun's gravity appears to be influencing their movements. One explanation is the presence of a giant, unseen planet, exerting enough gravity to mold their orbital journeys. Deputy Observing Specialist Manager Alysha Shugart commands the TMA and Dome from platform 8 at the observatory. The M3 inner mirror, outer M1 mirror and LSST Camera of Simonyi's Survey Telescope at Vera Rubin Observatory, Chile. May 30, 2025. There are other explanations that could explain the strange orbits, from the extravagant (perhaps there's a tiny black hole out there , or evidence for a new theory of gravity ), to the more mundane (maybe there's nothing odd about the orbits, and our picture of the Kuiper belt is just incomplete.) Existing telescopes aren't capable of spotting the faint glow of such a faraway maybe-planet. But Rubin may find Planet Nine within the first year or two operations, says Megan Schwamb , an astronomer at Queen's University, Belfast, in Northern Ireland. Scientists have worked out a search area in the night sky. If the planet is there, "we'll see it like we see Pluto," Schwamb says—a bright pinprick in the inky shadows of the Kuiper belt, reflecting the light of its star. Enormous cables on Level 5, beneath the Telescope Mount Assembly (TMA), at the Vera Rubin Observatory, Chile. The Simonyi Survey Telescope at Vera Rubin Observatory, Chile. May 30, 2025. If there's no grand X-marks-the-spot moment for Planet Nine, "that doesn't mean it's not there," Samantha Lawler , an astronomer at Campion College in Canada, says. "It could just be farther out, or it could be smaller or less reflective." Astronomers will need to keep scrutinizing the behavior of trans-Neptunian objects, and Rubin is poised to discover 37,000 trans-Neptunian objects, expanding the current catalog tenfold. In a sea of these newly found celestial bodies, convincing evidence of Planet Nine may float to the surface, or become washed away altogether. While Schwamb and Lawler would be delighted to welcome a new planet, they're thrilled at the prospect of learning more about the realm beyond Neptune, which is intriguing in its own right. The frozen objects in the Kuiper belt are remnants of the formation of our cosmic neighborhood, like eraser shavings brushed off to the side of the page, and astronomers can study them to better understand its bygone eras. "I have no doubt there will be other weird patterns that we see in those orbits that will lead to other interesting ideas about what may or may not be in our solar system now, and how it has changed over time," Lawler says. Among the questions that the Vera Rubin Observatory could help answer: Is there a Planet 9? Scientists hope that the observatory can help map the universe's dark matter. In 2017, a ground-based telescope in Hawaii caught an unusual object hurtling through the solar system, untethered from the gravity of the sun. Oumuamua , as the object was later named, left astronomers with many questions about a previously undiscovered cosmic population, and some wild conjectures about alien origins that are still floating around today. A second surprise object, named Borisov , showed up in 2019, further deepening the mystery. Rubin will provide many more opportunities to study these interstellar objects, which can coast through the galactic hinterlands for hundreds of millions of years before encountering the warmth of a star. These objects appear without warning, and move fast, so they can be difficult to catch—unless you're constantly making time lapses of the night sky. Rubin Observatory's Simonyi Survey Telescope during calibration. Interstellar objects are believed to be ejected from their home systems during planet formation, a notoriously turbulent time. (Bits of our own solar system, hurled away several billions of years ago, are likely floating somewhere in the galaxy.) Some researchers estimate that Rubin, over the course of its decade-long run, may discover between five and 50 interstellar objects. Chris Lintott, an astrophysicist at Oxford, is more optimistic, betting on 100. It's quite the range, which underscores just how new, and exciting, this area of study is. Each time Rubin detects an interstellar object, it will spark a frenetic chase: telescopes around the world and in space will track the target until it zooms out of reach, checking to see how it's moving, what it's made of, and—because why not?—whether it bears signs of artificial technology. Each cosmic wanderer Rubin finds will provide a glimpse of how planet formation may have unfolded across the Milky Way. Are giant planets like Jupiter, Saturn, and Uranus common around other stars? Rubin's interstellar catch of the day could help answer that question. Or its findings could indicate these types of planets are rarer than we thought. "If we find very few [interstellar objects], I think we might have to rethink what sort of planetary systems exist in the galaxy," Lintott says. Even with the powerful new observatory, astronomers likely won't be able to trace interstellar objects to their exact starting points "because they've been mixed around the galaxy so much," says Michele Bannister, a planetary astronomer at the University of Canterbury in New Zealand. But they can analyze their chemical composition to glean information about their home star, including its age. Scientists may even be able to determine if two or more interstellar objects originated from the same cluster of stars. And they can use Rubin's future catalog to test various theories, including whether entire corridors of these interstellar objects exist, winding through the galaxy like ribbons. Even a small sample of them "tells us so much about these processes happening across our whole wonderful, wide galaxy," Bannister says. From interstellar objects to galaxy formation, the new telescope will give astronomers a stunning new view of deep space. The Vera Rubin Observatory is named for the pioneering scientist who explored the mysteries of dark matter. Petr Kubánek, right, and Robinson Godoy Torres checking on actuators and valves inside the M1M3 mirror cells of the Simonyi Survey Telescope, Vera Rubin Observatory, Chile. May 30, 2025, Galaxies form in a messy process, says Barmby, the Western University astronomer. "There's gas falling in, there's gas getting blown out, there's stars forming, there's stars dying, and all of that stuff happens on super-long timescales that we can't actually watch happen." Sometimes, in the process, stars in one galaxy get taken up by the gravitational force of another. These are known as stellar streams, and the new observatory is expected to reveal many more of these in our own Milky Way, hovering like bees around the shimmering rose of the galaxy. Rubin's observations will allow astronomers to track the motions of individual stars over long periods of time, which can reveal whether they originated inside the Milky Way or came tumbling in from a nearby galaxy. Rubin is also expected to discover more of the small galaxies that orbit the Milky Way, which have unwillingly donated some of those stars. Each galaxy has its own fascinating cosmic personality; one of the smallest has just a few hundred stars, compared to the Milky Way's 10 billion, says Yao-Yuan Mao , an astrophysicist at the University of Utah. He expects that Rubin will discover all the little galaxies that can possibly be observed, not counting those that are situated behind the bright disk of the Milky Way, which will remain forever out of view from Earth's perspective. "We will get a super complete picture of our Milky Way system," Mao says. And by comparing our galaxy system with that of others, astronomers can tackle one of the most animating questions in the field: whether the way the cosmos works here, in our part of it, is the same as everywhere else. "The knowledge that we inferred from studying the Milky Way—is that generally applicable across the universe?" Mao says. "Or is there something special or unique about the Milky Way itself?" Observing Specialist Minhee Hyun, left, and Yijung Kang at the Control Room of Vera Rubin Observatory, Chile. May 30, 2025. As Rubin captures pictures of millions of cosmic objects, the observatory will also be searching for signs of two completely invisible things: dark matter and dark energy. All of the stars, galaxies, gas—all of the matter we can observe—turns out to be just 5 percent of "the total stuff in the universe," says Alex Drlica-Wagner , an astrophysicist at the University of Chicago. The rest is dark matter, a kind of matter that doesn't emit or absorb light, which accounts for 25 percent of the universe's composition, and dark energy, a phantom entity that makes up 70 percent. While scientists have never directly observed either, they've seen the cosmos behaving in certain ways that suggest they must exist. Rubin won't reveal all of their secrets, but the sheer amount of data will serve as a veritable playground for scientists to test their theories about these phenomena. Astronomers first suspected the existence of dark matter in the 1930s when they noticed that some galaxies remained clustered together even though they were traveling fast enough to fly apart, suggesting that another force was keeping the galactic web intact. In the 1970s, Rubin's namesake astronomer discovered a similar effect at the edges of galaxies, where whizzing stars that should have escaped were instead being held tight. The mark of the unseen material can even be found using starlight itself. The observatory's telescope will be the largest digital camera on the planet, a massive 3,200-megapixel camera. Dark matter can bend light as it passes by, making its source—a distant galaxy, for example—appear distorted. Rubin will collect these warped views, allowing astronomers to "map out where the dark matter is by how we see the light bending as it travels to us," Drlica-Wagner says. Those maps can help illuminate the nature of dark-matter particles, including whether they're cold or hot—seemingly small characteristics with the capacity to reshape our understanding of how the universe assembles galaxies. Dark energy is even more mysterious. The idea emerged in the 1990s, when astrophysicists calculated that the universe was expanding faster over time rather than slowing down, which ran counter to laws of physics that governed the rest of the cosmos. Dark energy was determined to be the driving force, although scientists don't know what it actually is, only that it appears to behave differently than anything else in the universe, Drlica-Wagner says. Unlike dark matter, which, like the regular cosmic stuff, is likely made up of some kind of particles, dark energy stretches the very fabric of space, pushing galaxies apart rather than drawing them together. Rubin's massive catalog of exploding stars will come in handy here: Scientists can use certain kinds of supernovas to trace the universe's expansion, and, in turn, dark energy's role in it. Rubin data could confirm or refute new theories that suggest dark energy is changing over time, rather than remaining constant, upending even Einstein's predictions for this perplexing force. The observatory is expected to return so much data, scientists are preparing to be overjoyed—and perhaps overwhelmed. In the end, the most exciting discoveries Rubin makes might be the ones astronomers haven't yet anticipated. Such is the nature of really good new telescopes: the thrill of what we don't know we don't know. "If someone says, I have never seen a six-foot-tall-rabbit, you can say, sure, how hard have you looked?" Michael Wood-Vasey, an astronomer at the University of Pittsburgh who has spent years helping to prepare the Rubin observatory for operations, says. Perhaps the new observatory, with its constant, scouring gaze, will turn up some cosmic rabbits.
