Space

What happens when two different kinds of auroras get together? One spills the other’s secrets.

Amateur astronomers have captured a strange combination of red and green auroras on camera, and physicists — who had never seen such a thing before — have now used these images to learn what may trigger the more mysterious part of the lightshow.

Photographer Alan Dyer was in his backyard in Strathmore, Canada, when he saw the lights dancing overhead and started filming. “I knew I had something interesting,” says Dyer, who also writes about astronomy. What he didn’t know was that he had just made the most complete recording of this rare phenomenon.

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At a glance, Dyer’s video looks like a celestial watermelon. The rind, a rippling green aurora, is well understood: It appears when the solar wind energizes protons trapped within Earth’s magnetic field, which then rain down and knock electrons and atoms around (SN: 12/10/03).  

The swath of fruity magenta is more mysterious: Though scientists have known about these “stable auroral red arcs” for decades, there’s no widely accepted proof of how they form. One popular theory is that part of Earth’s magnetic field can heat up the atmosphere and, like proton rain, jostle particles.   

But until now, researchers had never seen both of these red and green auroras side by side, says Toshi Nishimura, a space physicist at Boston University. “This strange combination,” he says, “was something beyond our expectations.”

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Alan Dyer’s footage of this rare double aurora, a time lapse captured over 33 minutes on October 12, 2021, is helping physicists tease out clues to what causes the red glow.

Along with satellite observations, Dyer’s images and similar ones captured by other amateur astronomers in Canada and Finland show that the two phenomena are related, Nishimura’s team reports in the July JGR Space Physics. Thin rays in the red aurora are the smoking gun as to how. Those lines trace the paths of electrons as they fall along the Earth’s magnetic field. So just as proton rain triggers the green aurora, electron rain appears to trigger the red one, with the solar wind powering both at the same time. Since the electrons carry less energy than the protons, they make for a more reddish color. 

But electron rain might not be the only way to produce these red glows, cautions Brian Harding, a space physicist at the University of California, Berkeley. Either way, he says, the results are exciting because they show what’s going on is more complicated than researchers thought.

Those complications are important to understand. The auroras Dyer saw, though beautiful, are danger zones for radio communication and GPS systems (SN: 8/13/17). As Nishimura puts it: If you were driving under a subauroral red arc, your GPS might tell you to veer into a field.

Until scientists better understand these red glows, they won’t be able to forecast space weather like they do normal weather, Harding explains. “You want to make sure that you can predict stuff like this,” he says.

The new results would not have been possible without the citizen scientists who took the photos, Nishimura says. “This is a new way of doing research…. When they take more and more cool images, they find more and more things that we don’t know about.”

According to Dyer, more photos are exactly what’s coming. “We can make a unique contribution to science,” he says.  After all, “you never know what’s going to appear.” More

As astronomy datasets grow larger, scientists are scouring them for black holes, hoping to better understand the exotic objects. But the drive to find more black holes is leading some astronomers astray.

“You say black holes are like a needle in a haystack, but suddenly we have way more haystacks than we did before,” says astrophysicist Kareem El-Badry of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. “You have better chances of finding them, but you also have more opportunities to find things that look like them.”

Two more claimed black holes have turned out to be the latter: weird things that look like them. They both are actually double-star systems at never-before-seen stages in their evolutions, El-Badry and his colleagues report March 24 in Monthly Notices of the Royal Astronomical Society. The key to understanding the systems is figuring out how to interpret light coming from them, the researchers say.  

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In early 2021, astronomer Tharindu Jayasinghe of Ohio State University and his colleagues reported finding a star system — affectionately named the Unicorn — about 1,500 light-years from Earth that they thought held a giant red star in its senior years orbiting an invisible black hole. Some of the same researchers, including Jayasinghe, later reported a second similar system, dubbed the Giraffe, found about 12,000 light-years away.

But other researchers, including El-Badry, weren’t convinced that the systems harbored black holes. So Jayasinghe, El-Badry and others combined forces to reanalyze the data.

To verify each star system’s nature, the researchers turned to stellar spectra, the rainbows that are produced when starlight is split up into its component wavelengths. Any star’s spectrum will have lines where atoms in the stellar atmosphere have absorbed particular wavelengths of light. A slow-spinning star has very sharp lines, but a fast-spinning one has blurred and smeared lines.

“If the star spins fast enough, basically all the spectral features become almost invisible,” El-Badry says. “Normally, you detect a second star in a spectrum by looking for another set of lines,” he adds. “And that’s harder to do if a star is rapidly rotating.”

That’s why Jayasinghe and colleagues misunderstood each of these systems initially, the team found.

“The problem was that there was not just one star, but a second one that was basically hiding,” says astrophysicist Julia Bodensteiner of the European Southern Observatory in Garching, Germany, who was not involved in the new study. That second star in each system spins very fast, which makes them difficult to see in the spectra.

What’s more, the lines in the spectrum of a star orbiting something will shift back and forth, El-Badry says. If one assumes the spectrum shows just one average, slow-spinning star in an orbit — which is what appeared to be happening in these systems at first glance — that assumption then leads to the erroneous conclusion that the star is orbiting an invisible black hole.

Instead, the Unicorn and Giraffe each hold two stars, caught in a never-before-seen stage of stellar evolution, the researchers found after reanalyzing the data. Both systems contain an older red giant star with a puffy atmosphere and a “subgiant,” a star on its way to that late-life stage. The subgiants are near enough to their companion red giants that they are gravitationally stealing material from them. As these subgiants accumulate more mass, they spin faster, El-Badry says, which is what made them undetectable initially.

“Everyone was looking for really interesting black holes, but what they found is really interesting binaries,” Bodensteiner says.

These are not the only systems to trick astronomers recently. What was thought to be the nearest black hole to Earth also turned out to be pair of stars in a rarely seen stage of evolution (SN: 3/11/22).

“Of course, it’s disappointing that what we thought were black holes were actually not, but it’s part of the process,” Jayasinghe says. He and his colleagues are still looking for black holes, he says, but with a greater awareness of how pairs of interacting stars might trick them. More

Space exploration may seem like a faraway endeavor from Earth’s surface, but events on the ground ripple into space. The Russian war on Ukraine is no exception.

From a rocket launch system to a rover set to explore Mars, a wide range of space missions is facing postponements or cancelations due to escalating tensions on the ground in the wake of Russia’s full-scale invasion into Ukraine on February 24. The European Union, United States and others have imposed sanctions on Russia; Russia, as a result, is continually changing and canceling its space-related plans. The shifts are having an impact on everything from international collaborations to missions that rely on Russian rockets to get to space.

Here’s a closer look at some of those projects.

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ExoMars rover

The ExoMars mission is a partnership between the European Space Agency and the Russian space agency Roscosmos. This is a two-part mission to Mars consisting of an orbiter and a rover. The orbiter has been at the Red Planet since late 2016, but the Rosalind Franklin rover was supposed to launch this September (SN: 10/18/16).

“The sanctions and the wider context make a launch in 2022 very unlikely,” the European Space Agency, or ESA, said in a February 28 statement in response to Russia’s invasion of Ukraine.

Due to Earth’s and Mars’ orbital geometry, the most direct trajectory for a spacecraft from our planet to Mars repeats every two years, and that launch window remains open for less than two weeks. The ExoMars rover, which will look for signs of past life, was originally to launch in 2020, but due to the pandemic and technical issues, it slipped to 2022 (SN: 3/12/20). Now it’s at risk of slipping again to 2024.

The eROSITA telescope

Spectrum-Roentgen-Gamma is a space-based X-ray observatory, run jointly by Germany and Russia, that has been mapping the large-scale structure of the universe for the last two and a half years (SN: 7/8/20). The probe’s main telescope, eROSITA, has discovered hundreds of celestial objects, including a bizarre stellar explosion known as a “cow” (SN: 1/21/22). On February 26, the Germans placed eROSITA into safe mode as an action to “freeze co-operation with Russia,” according to a statement from SRG leadership at the Max Planck Institute in Garching, Germany.  

“This is a standard, reversible, operation mode of the telescope, in which we do not take data, but keep the vital subsystems on,” says Andrea Merloni, an astronomer at the Max Planck Institute for Extraterrestrial Physics, also in Garching, and eROSITA’s project scientist. He declined to comment on any other aspect of the mission or collaboration with Russia.

The Russian News Agency TASS reported March 1 that Roscosmos intends to estimate the financial loss of that safe-mode action and other European space-related sanctions, and the Russian space agency will then bill “the European side” of the projects.

ESA, meanwhile, is “assessing the consequences on each of our ongoing programmes conducted in cooperation with the Russian state space agency,” the agency said in its February 28 statement.

Navigation satellites

In response to international sanctions against Russia, the head of Roscosmos announced February 26 that the agency was suspending cooperation with the European spaceport in Kourou, French Guiana, and withdrawing its dozens of employees from the site. Several space missions were set to launch from this location via a Russian Soyuz rocket in the next year, including a pair of European navigation satellites in early April.

These satellites would have joined with the already-launched two dozen that make up the Galileo navigational system, the European answer to the United States’ GPS system. Two additional Galileo satellites are also in orbit, but they were placed incorrectly and instead focus on science and search and rescue (SN: 12/10/18).

OneWeb internet network

The U.K. company OneWeb, which is building a space-based internet network with hundreds of low-Earth satellites, is also facing a launch postponement.

A Soyuz rocket was scheduled to send up a few dozen OneWeb satellites March 4, one of a series of launches aimed at completing the network in 2022. But in the early hours of March 2, the head of Roscosmos tweeted the space agency wouldn’t launch the satellites without a guarantee from the company that they wouldn’t be used for military purposes. He also demanded the U.K. government sell its share of the mission, which it has refused to do.

Venera-D mission to Venus

The Russian-Ukraine war has also affected U.S. space activities, but to a lesser extent than its impact on its European counterparts. NASA has relationships with several commercial partners, so the agency relies less on Roscosmos. But NASA is still feeling some effects.

For instance, in retaliation to U.S. sanctions, the head of Roscosmos tweeted on February 26 that NASA’s participation in the Russian-led Venera-D mission to Venus would be “inappropriate.” This mission will include an orbiter, lander and surface station, and it will focus on understanding Venus’s former and present habitability.

However, Venera-D won’t launch until late this decade, and NASA has been involved only in some planning groups. The U.S. space agency already has two of its own Venus missions in the works (SN: 6/02/21).

International Space Station

While many areas of cooperation in space with Russia are fraying, the International Space Station collaboration so far remains unchanged. “NASA continues working with all our international partners, including the State Space Corporation Roscosmos, for the ongoing safe operations of the International Space Station,” NASA public affairs officer Joshua Finch, at Kennedy Space Center in Cape Canaveral, said in an e-mailed statement.

Currently, there are two Russian cosmonauts, four NASA astronauts and one ESA astronaut aboard the station. Later this month, a Russian Soyuz capsule is set to return the two cosmonauts and one of the NASA astronauts to Earth, landing in Kazakhstan as scheduled, Finch said.

However, during a March 1 NASA Advisory Council meeting, Wayne Hale, a former NASA associate administrator, recommended the U.S. space agency consider contingencies in case Russia no longer collaborates on the space station. At the same meeting the following day, former U.S. representative Jane Harman recommended that NASA think about what cooperation with Russia will look like going forward. More

The moon’s violent history is written across its face. Over billions of years, space rocks have punched craters into its surface, flinging out debris. Now, for the first time, astronomers may have spotted rubble from one of those ancient smashups out in space. The mysterious object known as Kamoʻoalewa appears to be a stray fragment of the moon, researchers report online November 11 in Communications Earth & Environment.

Discovered in 2016, Kamoʻoalewa — also known as 2016 HO3 — is one of Earth’s five known quasisatellites (SN: 6/24/16). These are rocks that stick fairly close to the planet as they orbit the sun. Little is known about Earth’s space rock entourage because these objects are so small and faint. Kamoʻoalewa, for instance, is about the size of a Ferris wheel and strays between 40 and 100 times as far from Earth as the moon, as its orbit around the sun weaves in and out of Earth’s. That has left astronomers to wonder about the nature of such tagalong rocks.

“An object in a quasisatellite orbit is interesting because it’s very difficult to get into this kind of orbit — it’s not the kind of orbit that an object from the asteroid belt could easily find itself caught in,” says Richard Binzel, a planetary scientist at MIT not involved in the new work. Having an orbit nearly identical to Earth’s immediately raises suspicions that an object like Kamoʻoalewa originated in the Earth-moon system, he says.

Researchers used the Large Binocular Telescope and the Lowell Discovery Telescope, in Safford and Happy Jack, Ariz., respectively, to peer at Kamoʻoalewa in visible and near-infrared wavelengths. “The real money is in the infrared,” says Vishnu Reddy, a planetary scientist at the University of Arizona in Tucson. Light at those wavelengths contains important clues about the minerals in rocky bodies, helping distinguish objects such as the moon, asteroids and terrestrial planets.

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Kamoʻoalewa reflected more sunlight at longer, or redder, wavelengths. This pattern of light, or spectrum, looked unlike any known near-Earth asteroid, Reddy and colleagues found. But it did look like grains of silicate rock from the moon brought back to Earth by Apollo 14 astronauts (SN: 2/20/71).

“To me,” Binzel says, “the leading hypothesis is that it’s an ejected fragment from the moon, from a cratering event.”

Martin Connors, who was involved in the discovery of Earth’s first known quasisatellites but did not participate in the new research, also suspects that Kamoʻoalewa is a chip off the old moon. “This is well-founded evidence,” says Connors, a planetary scientist at Athabasca University in Canada. But, he cautions, “that doesn’t mean it’s right.”

More detailed observations could help confirm Kamoʻoalewa is made of moon stuff. “If you really wanted to put that nail in the coffin, you’d want to go and visit, or rendezvous with this little quasisatellite and take a lot of up-close observations,” says Daniel Scheeres, a planetary scientist at the University of Colorado Boulder not involved in the work. “The best would be to get a sample.”

China’s space agency has announced plans to send a probe to Kamoʻoalewa to scoop up a bit of rock and bring it back to Earth later this decade. More

From the maw of the supermassive black hole at the center of the galaxy M87, two enormous jets stream thousands of light-years into space. Scientists still don’t fully understand the physics behind the jets, which are made of a mix of electrically charged particles, or plasma (SN: 3/24/21). But they are “really, really amazing,” says astrophysicist Alejandro Cruz-Osorio of Goethe University Frankfurt. So he and colleagues created a computer simulation of M87’s black hole and the swirling gas that surrounds it in an accretion disk. The aim: Figure out how this black hole — already famous for posing for a picture in 2019 (SN: 4/10/19) — became such a jet-setter.

Under the right conditions, that simulation produces jets that match observations of M87, the researchers report November 4 in Nature Astronomy. The black hole twists up spiraling magnetic fields that surround two high-energy beams of electrons and other charged particles. The results suggest that the black hole must be spinning rapidly, at more than half its maximum speed allowed by the laws of physics and possibly as much as 94 percent of its maximum possible speed.

Getting the energies of the jets’ electrons right turned out to be crucial. When magnetic fields in the jets rearrange in a process known as magnetic reconnection (SN: 8/3/21), electrons get accelerated, resulting in more of them having very high energies. This effect was not included in earlier simulations, but it was key to getting the simulated jets to act like real-world counterparts. More

A mad scramble to observe the moments after a star’s death is helping scientists understand how the star lived out its last year.

Astronomers reported the exploding star just 18 hours after it flared up on March 31, 2020, in a galaxy about 60 million light-years away from Earth in the Virgo cluster. The supernova occurred in part of the sky already watched by NASA’s Transiting Exoplanet Survey Satellite, which images large portions of the sky every 30 minutes (SN: 1/8/19). And a team of scientists quickly realized that data would track precisely how the eruption brightened over time, making it ideal for further study. 

To learn even more, the team leapt into action, viewing the supernova with a variety of telescopes in the hours and days that followed, even orchestrating a last-minute change of plans for the Hubble Space Telescope. That provided the supernova’s spectrum, an accounting of its light broken up by wavelength, at various moments after the blast.

All that data revealed that in the last year of its life, the star had spewed some of its outer layers into space, researchers report October 26 in Monthly Notices of the Royal Astronomical Society. The amount of material ejected was about 0.23 times the mass of the sun, the team estimates. When the supernova went off, it launched a shock wave that plowed through that material shortly after the explosion, generating light picked up by the telescopes.

As large stars get closer to death, they may start behaving erratically. Aging stars fuse heavier and heavier elements in their cores. For this star, the switch to fusing oxygen could have triggered that shedding in its last year, astrophysicist Samaporn Tinyanont of the University of California, Santa Cruz and colleagues suggest. “These stars have a roller coaster last few years of their life,” Tinyanont says.

Scientists hope that understanding that roller coaster ride could help them recognize when other stars are about to blow. More

For the first time, a spacecraft is headed to Jupiter’s odd Trojan asteroids. What Lucy finds there could provide a fresh peek into the history of the solar system.

“Lucy will profoundly change our understanding of planetary evolution in our solar system,” Adriana Ocampo, a planetary scientist at NASA Headquarters in Washington, D.C., said at a news briefing October 14.

The mission is set to launch from the Kennedy Space Center at Cape Canaveral, Fla., as early as October 16. Live coverage will air on NASA TV beginning at 5 a.m. EDT, in anticipation of a 5:34 a.m. blast off.

The Trojan asteroids are two groups of space rocks that are gravitationally trapped in the same orbit as Jupiter around the sun. One group of Trojans orbits ahead of Jupiter; the other follows the gas giant around the sun. Planetary scientists think the Trojans could have formed at different distances from the sun before getting mixed together in their current homes. The asteroids could also be some of the oldest and most pristine objects in the solar system.

The mission will mark several other firsts, from the types of objects it will visit to the way it powers its instruments. Here are five cool things to know about our first visit to the Trojans.

1. The Trojan asteroids are a solar system time capsule.

The Trojans occupy spots known as Lagrangian points, where the gravity from the sun and from Jupiter effectively cancel each other out. That means their orbits are stable for billions of years.

“They were probably placed in their orbits by the final gasp of the planet formation process,” the mission’s principal investigator Hal Levison, a planetary scientist at Southwest Research Institute in Boulder, Colo.,  said September 28 in a news briefing.

But that doesn’t mean the asteroids are all alike. Scientists can tell from Earth that some Trojans are gray and some are red, indicating that they might have formed in different places before settling in their current orbits. Maybe the gray ones formed closer to the sun, and the red ones formed farther from the sun, Levison speculated.

Studying the Trojans’ similarities and differences can help planetary scientists tease out whether and when the giant planets moved around before settling into their present positions (SN: 4/20/12). “This is telling us something really fundamental about the formation of the solar system,” Levison said.

2. The spacecraft will visit more individual objects than any other single spacecraft. 

Lucy will visit eight asteroids, including their moons. Over its 12-year mission, it will visit one asteroid in the main asteroid belt between Mars and Jupiter, and seven Trojans, two of which are binary systems where a pair of asteroids orbit each other.

“We are going to be visiting the most asteroids ever with one mission,” planetary scientist Cathy Olkin, Lucy’s deputy principal investigator, said in the Oct. 14 briefing.

The spacecraft will observe the asteroids’ composition, shape, gravity and geology for clues to where they formed and how they got to the Lagrangian points.

The spacecraft’s first destination, in April 2025, will be an asteroid in the main belt. Next, it will visit five asteroids in the group of Trojans that orbit the sun ahead of Jupiter: Eurybates and its satellite Queta in August 2027; Polymele in September 2027; Leucus in April 2028; and Orus in November 2028. Finally, the spacecraft will shift to Jupiter’s other side and visit the twin asteroids Patroclus and Menoetius in the trailing group of space rocks in March 2033.

The spacecraft won’t land on any of its targets, but it will swoop within 965 kilometers of their surfaces at speeds of 3 to 5 meters per second relative to the asteroids’ speed through space.

There’s no need to worry about collisions while zipping through these asteroid clusters, Levison said. Although there are about 7,000 known Trojans, they’re very far apart. “If you were standing on any one of our targets, you wouldn’t be able to tell you were part of the swarm,” he said.

The Trojan asteroids trail and follow Jupiter in its orbit around the sun, but they’re actually quite far from the giant planet. In fact, Earth is closer to Jupiter than either swarm of Trojans is.NASA, adapted by T. TibbittsThe Trojan asteroids trail and follow Jupiter in its orbit around the sun, but they’re actually quite far from the giant planet. In fact, Earth is closer to Jupiter than either swarm of Trojans is.NASA, adapted by T. Tibbitts

3. Lucy will have a weird flight path.

In order to make so many stops, Lucy will need to take a complex path. First, the spacecraft will swoop past Earth twice to get a gravitational boost from our planet that will help propel it onward to its first asteroid.

The closest Earth flyby, in October 2022, will take it within 300 kilometers of the planet’s surface, closer than the International Space Station, the Hubble Space Telescope and many satellites, Olkin said. Observers on Earth might even be able to see it. “I’m hoping to go near where it flies past and look up and see Lucy flying by a year from now,” she said.

Then in December 2030, after more than a year exploring the “leading” swarm of Trojans, Lucy will come back to the vicinity of Earth for one more boost. That final gravitational slingshot will send the spacecraft to the other side of the sun to visit the “trailing” swarm. This will make Lucy the first spacecraft ever to venture to the outer solar system and come back near Earth again.

4. Lucy will travel farther from the sun than any other solar-powered craft.

Another record Lucy will break has to do with its power source: the sun. Lucy will run on solar power out to 850 million kilometers away from the sun, making it the farthest-flung solar powered spacecraft ever.

To accomplish that, Lucy has a pair of enormous solar arrays. Each 10-sided array is more than 7.3 meters across and includes about 4,000 solar cells per panel, Lucy project manager Donya Douglas-Bradshaw said in a news briefing on October 13. Standing on one end, Lucy and its solar panels would be as tall as a five-story building.

“It’s a very intricate, sophisticated design,” she said. The advantage of using solar power is that the team can adjust how much power the spacecraft needs based on how far from the sun it is.

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5. The inspiration for Lucy’s name is decidedly earthbound.

NASA missions are often named for famous scientists, or with acronyms that describe what the mission will do. Lucy, on the other hand, is named after a fossil.

The idea that the Trojans hold secrets to the history of the solar system is part of how the mission got its unusual name. To understand, go back to 1974, when paleoanthropologist Donald Johanson and a graduate student discovered a fossil of a human ancestor who had lived 3.2 million years ago. After listening to the Beatles song “Lucy in the Sky with Diamonds” at camp that night, Johanson’s team named the fossil hominid “Lucy.” (In a poetic echo, the first asteroid the Lucy spacecraft will visit is named Donaldjohanson.)

Planetary scientists hope the study of the Trojans will revolutionize our understanding of the solar system’s history in the same way that studying Lucy’s fossil revolutionized our understanding of human history.

“We think these asteroids are fossils of solar system formation,” Levison said. So his team named the spacecraft after the fossil. 

The spacecraft even carries a diamond in one of its instruments, to help split beams of light. Said planetary scientist Phil Christensen of Arizona State University in Tempe at the Oct. 14 briefing: “We truly are sending a diamond into the sky with Lucy.” More

Bright Galaxies, Dark Matter, and BeyondAshley Jean YeagerMIT Press, $24.95

Vera Rubin’s research forced cosmologists to radically reimagine the cosmos.

In the 1960s and ’70s, Rubin’s observations of stars whirling around within galaxies revealed the gravitational tug of invisible “dark matter.” Although astronomers had detected hints of this enigmatic substance for decades, Rubin’s data helped finally convince a skeptical scientific community that dark matter exists (SN: 1/10/20).

“Her work was pivotal to redefining the composition of our cosmos,” Ashley Yeager, Science News’ associate news editor, writes in her new book. Bright Galaxies, Dark Matter, and Beyond follows Rubin’s journey from stargazing child to preeminent astronomer and fierce advocate for women in science.

That journey, Yeager shows, was rife with obstacles. When Rubin was a young astronomer in the 1950s and ’60s, many observatories were closed to women, and more established scientists often brushed her off. Much of her early work was met with intense skepticism, but that only made Rubin, who died in 2016 at age 88, a more dogged data collector.

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On graphs plotting the speeds of stars swirling around galaxies, Rubin showed that stars farther from galactic centers orbited just as fast as inner stars. That is, the galaxies’ rotation curves were flat. Such speedy outer stars must be pulled along by the gravitational grip of dark matter.

Science News staff writer Maria Temming spoke with Yeager about Rubin’s legacy and what, beyond her pioneering research, made Rubin remarkable. The following discussion has been edited for clarity and brevity.

Temming: What inspired you to tell Rubin’s story?

Yeager: It all started when I was working at the National Air and Space Museum in Washington, D.C., in 2007. I was walking around the “Explore the Universe” exhibit and noticed there weren’t many women featured. But then there was this picture of a woman with big glasses and cropped hair, and I thought, “Who is this?” It was Vera Rubin.

My supervisor was a curator of oral histories. He was working on Rubin’s, so I asked him about her. He said, “I have one more oral history interview to do with her. Would you like to come?” So I got to interview her. She was charismatic, kind and curious — not a person who was all about herself, but wanted to know about you. That stuck with me.

Temming: You spend much of the book describing evidence for dark matter besides Rubin’s research. Why?

Yeager: I wanted to make sure I didn’t portray Rubin as this lone person who discovered dark matter, because there were a lot of different moving pieces in astronomy and physics that came together in the ’70s and early ’80s for the scientific community to say, “OK, we really have to take dark matter seriously.”

Temming: What made Rubin’s work a linchpin for confirming dark matter?

Yeager: She really went after nailing down that flat rotation curve in all types of galaxies. Mainly because she did get a lot of pushback, continually, that said, “Oh, that’s just a special case in that galaxy, or that’s just for those types of galaxies.” She studied hundreds of galaxies to double-check that, yes, in fact, the rotation curves are flat. People saying, “We don’t believe you,” didn’t ever really knock her down. She just came back swinging harder.

It helped that she did the work in visible wavelengths of light. There had been a lot of radio astronomy data to suggest flat rotation curves, but because radio astronomy was very new, it was really only once you saw it with the eye that the astronomy community was convinced.

Temming: Do you have a favorite anecdote about Rubin?

Yeager: The one that comes to mind is how much she loved flowers. She told me about how on drives from Lowell Observatory to Kitt Peak National Observatory in Arizona, she and her colleague Kent Ford would always stop and buy wildflowers. The fact that picking these wildflowers stuck with her, I thought, was just representative of who she was. Her favorite moments weren’t necessarily these big discoveries she’d made, but stopping to pick some flowers and enjoy their beauty.

Author Ashley Yeager (left) interviewed Vera Rubin (right) in 2007 as part of an oral history project with Smithsonian’s National Air and Space Museum.Smithsonian National Air and Space Museum (NASM 9A16674)

Temming: Did you learn anything in your research that surprised you?

Yeager: I didn’t initially grasp how many different types of projects she had. She did a lot with looking for larger-scale structure [in the universe] and looking at the Hubble constant [which describes how fast the universe is expanding] (SN: 4/21/21). She had a very diverse set of questions that she wanted to answer, well into her 70s.

Temming: I was surprised by her decision to get out of the rat-race of hunting for quasars, when that area of research heated up in the 1960s.

Yeager: She very much didn’t like to be in pressure situations where she could be wrong. She liked to go and collect so much data that no one could [dispute it]. With quasar research, it was just too fast, and she wanted to be methodical about it.

Temming: Why is Rubin’s story important to tell now?

Yeager: Unfortunately for women and minorities in science, it’s still very relevant, in that there are a lot of challenges to pursuing a career in STEM. Her story demonstrates that you have to surround yourself with people who are willing to help you and get away from the people who want to keep you down. Plus her story is also very encouraging: Your curiosity can keep you going and can fuel something way bigger than yourself.

Temming: How did she advocate for women in astronomy?

Yeager: She was very outspoken about it. At National Academy of Sciences meetings, the organizers always dreaded her standing up, because she would say, “What are we doing about women in science? We’re not doing enough.” She was constantly pushing for women to be recognized with awards. She kept tabs on the number of women who had earned Ph.D.s and who had gotten staff positions — and their salaries. She was very data-driven. She’d cull that information and use it to advocate for better representation and recognition of women in astronomy.

Temming: How would you describe Rubin to someone who hasn’t met her?

Yeager: She was one of the most persistent, gracious and nurturing people that I’ve ever met. You could strip away all that she did in astronomy and she would still be this incredible figure — the way she carried herself, the way she treated people. Just a beautiful human being.

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