How One Astronomer Helped to Discover Nearly 200 Moons of Saturn
A mere decade ago, astronomers knew of just 62 moons around Saturn. Today the ringed planet boasts a staggering 274 official satellites. That's more than any other world in the solar system—and far too many for most people to keep track of. Astronomer Edward Ashton is no exception, even though he has helped to discover 192 of them—he thinks that's the total, anyway, after pausing to do some mental math.
Ashton is now a postdoctoral fellow at the Academia Sinica Institute of Astronomy and Astrophysics in Taiwan. He fell into hunting for Saturn's moons in 2018, when his then academic adviser suggested the project for his Ph.D. at the University of British Columbia. It has been a fruitful search. Most recently, in March, Ashton and his colleagues announced a batch of 128 newfound Saturnian satellites.
Scientific American spoke with Ashton about the science of discovering so many relatively tiny moons—most of them just a few kilometers wide—using vast amounts of data gathered by the Canada-France-Hawaii Telescope (CFHT), located in Hawaii.
On supporting science journalism
If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.
[ An edited transcript of the interview follows.]
How have you found these moons?
To detect the moons, we use a technique known as shifting and stacking. We take 44 sequential images of the same patch of sky over a three-hour period because, in that time frame, the moons move relative to the stars at a rate similar to Saturn. If we just stack the images normally, then the moon appears as a streak across the images, and that dilutes the signal of the moon.
So what we do is: we shift the images relative to one another at multiple different rates near that of Saturn, and then we basically blink between the different shift rates. If the shift rate is not quite at the rate of the moon, then it's going to be slightly elongated. As you get closer to the rate of the moon, then it slowly combines into a dot. And then, as you get faster than the moon's rate, it expands again. So basically, we look at the images and then quickly blink through the different rates, and you can see the moon coalescing.
That's for a single night. But just seeing an object moving at a Saturn-like rate near Saturn doesn't guarantee that it is a moon. It's highly likely that the object is a moon, but that hasn't been confirmed. So what we need to do is track the objects to show that they are in orbit around the planet. To do that, we repeat the [shift and stack] process multiple times over many months and years.
Why did this happen now? Did you need new techniques and observatories to do this work?
The technique and the technology have been there for a while—the same technique has been used to find moons of Neptune and Uranus. But the sky area around those planets where moons can exist is a lot smaller, so it takes less time to search through the data. One of the reasons why this hadn't been done for Saturn is because it's very time-consuming.
Why do those other planets have less space where moons could be than Saturn does?
Those planets are less massive, so the stable orbits that moons can have are smaller.
I had been wondering if this technique works for other planets, and clearly the answer is yes. But do you think there are other moons that have yet to be found around Saturn or other planets with the method?
We did find moon candidates around Saturn that we weren't able to track long enough to be able to confirm them. So if you redo this technique again, you will be able to find more moons around Saturn, but this is a case of diminishing returns. If you use a larger telescope [than the CFHT], then you'd be able to see fainter moons, so you'd be able to find more.
At the moment, if you use the same technique for Jupiter, you will be able to find fainter moons. The problem is: the amount of sky that moons of Jupiter can occupy is significantly larger than [the amount of sky that can be occupied by moons of] Saturn, so the method is even more time-consuming for Jupiter. And Jupiter is much brighter than Saturn and the other planets, so there's a lot of scattered light that makes it harder to see the moons.
So it's even harder to find satellites around Jupiter, and as you mentioned, other groups have already done this work for Uranus and Neptune. Does that mean we're sort of 'maxed out' on moons until we have better observations?
Yeah, you probably have to wait until better technology comes along.
Is there something being built or planned right now that could be that 'better technology'?
There currently are telescopes that can see deeper [than the CFHT], such as the James Webb Space Telescope (JWST). The problem is: JWST's field of view is very small, so you have to do quite a few observations to be able to cover the required area. But there is a telescope that's set to launch pretty soon, the Nancy Grace Roman Space Telescope, that has quite a large field of view. So that'll be a good telescope to use for hunting more moons.
What do we know about these new moons?
You basically can only get the moons' orbits and approximate sizes. But if you look at the distribution of the orbits, you can understand a bit more about the history of the system. Moons that are sort of clumped together in orbital space are most likely the result of a collision, so you can see what moons come from the same parent object.
Is seeing so many moons around Saturn unusual?
What's unusual is how many there are. It appears that the planets have more or less equal numbers of the larger moons. But when you get down to the smaller ones that we're discovering, Saturn seems to shoot up in terms of the numbers. So that's quite interesting. This could just be because there was a recent collision within the Saturnian system that produced a large number of fragments.
Do you get to name them all? Do you have to name them all?
I guess I don't have to. Some of these new moons, they've been linked back to observations by a different group from more than 10 years ago. That's maybe 20 to 30 of them. For the rest, we get full discovery credit, which, I think, means we get the right to name them. But they can't be named just yet; first, they're just given a number when they have a high-precision orbit, and I'm not sure how long that's going to take.
Do you have more moon-hunting observations to analyze?
No, I'm taking a little break from moons! I've got other projects to work on, relating to trans-Neptunian objects. They're quite far away. They're hard to see. There are some mysteries about them at the moment. It's interesting to understand their structure and how it relates to planet formation.
Hashtags
Try Our AI Features
Explore what Daily8 AI can do for you:
Comments
No comments yet...
Related Articles
Yahoo
2 hours ago
- Yahoo
Marc Garneau left lasting legacy on Earth and in space, former colleagues say
MONTREAL — Canadian scientists working on asteroid missions, exploring the universe through the James Webb Space Telescope or helping to put rovers on Mars say they can in some way thank Marc Garneau, who left an enduring legacy both as an astronaut and head of the country's space agency. While best-known in later years as a federal cabinet minister, Garneau, who died this week at 76, was also a Navy officer, a systems engineer, and an astronaut with a lifelong passion for science, according to his friends and colleagues. In 1984, he made history as the first Canadian in space when he served as a payload specialist aboard the Space Shuttle Challenger. He returned to space twice more, in 1996 and 2000, before serving as the president of the Canadian Space Agency from 2001 to 2005. "All his life was devoted to public service," said Gilles Leclerc, an ex-CSA official who worked with him. "And he was really a role model to all the Canadian astronauts who came after him." As CSA president, Garneau laid the building blocks for the space exploration program that would bring together other initiatives previously developed separately, Leclerc said. He was also "ahead of his time" when it came to being conscious of the environment and understanding the importance of applying space technology for practical uses such as satellite communications. "During his tenure, he really wanted us to focus more on science: astronomy, planetary science, lunar exploration," Leclerc said in a phone interview. "So all these things that now we see, all these missions that Canada participated in, like a mission to the asteroids, two missions to Mars, the James Webb Space had a real strong influence in shaping the future of the space program for a long time." On Friday, CSA President Lisa Campbell paid tribute to Garneau, who she called a "cherished member of the space agency family." "We remain deeply grateful for his extraordinary public service and enduring contributions to Canada and the world, from making history as the first Canadian in space to guiding the Canadian Space Agency as its president," she said at an event at the agency's Montreal-area headquarters. "his integrity, his generosity of spirit touches everyone who had the privilege of working with him." Flags at government buildings in Montreal have been lowered to half-mast in tribute. Garneau would carry his love of science — as well as his significant technical knowledge — into his next role as a politician, according to his former chief of staff and close personal friend. Marc Roy said Garneau decided to run for office out of a desire to give back after his successful space career. Garneau often spoke about how seeing the Earth from above "changed his perspective on many things," including conflicts and environmental protections, Roy said. "So many things that unfortunately divide us as humans that become so irrelevant when you look at our world from abroad," Roy said in a phone interview. "And that desire to want to contribute at an even higher level, at a different, at a policy level, at a governance level is what inspired him to run for federal politics." Garneau was elected as MP in Notre-Dame-de-Grâce–Westmount in 2008 after failing to win another Montreal-area seat in 2006. Roy said Garneau's scientific background shone through most clearly as Transport minister, when he was able to instantly grasp technical briefings on ships, planes and trains. Above all, his history as a naval officer and astronaut gave him a laser focus on safety, Roy said, in a role that would see Garneau introduce measures including the safer skies initiative, and the oceans protection plan to monitor ship traffic, oil spills and wildlife. Roy said Garneau often spoke about the weight of the portfolio, "wanting to ensure that he did it to the best of his ability, that he truly understood every decision that he was taking and every decision that was possible for him to make in order to ensure the safety of the traveling public and the safety overall of our trade and transportation corridors." Roy said Garneau brought a scientist's analytic, "Spock-like" demeanor to his roles. But he said some of the issues Garneau championed most passionately were social causes, including serving as a joint chair of the special joint committee on medical assistance in dying. And, despite his considerable intelligence, Roy said Garneau remained humble. "He had a very rare quality in a politician, from his very debut until the very last day before he retired as member of Parliament, which was: he listened more than he talked," Roy said. He said his friend was diagnosed only months ago with two cancers: leukemia and lymphoma, and died after a battle that was "brave but short." Roy said his friend's time since retirement was spent enjoying time with his wife, Pam, and his children, and completing work on his autobiography, "A Most Extraordinary Ride: Space, Politics and the Pursuit of a Canadian Dream." Roy said the book gave Garneau closure. "He wanted to tell the story that, 'I'm just like everybody else and I failed and I've screwed up and I pulled up my socks and I learned from my mistakes and I moved on,'" Roy said. "And that was very important for him to tell that story, and I'm just so fortunate that he had the time to do that." This report by The Canadian Press was first published June 7, 2025. Morgan Lowrie and Sidhartha Banerjee, The Canadian Press Error while retrieving data Sign in to access your portfolio Error while retrieving data Error while retrieving data Error while retrieving data Error while retrieving data
Yahoo
4 hours ago
- Yahoo
Antarctic treaty under stress as member countries gather in Italy
For 65 years, an international treaty forged at the height of the Cold War has governed Antarctica. But with rising geopolitical tensions, consensus is increasingly hard to find. "Up until just a few years ago, we talked about the Antarctic Treaty as a framework for peace and stability in the Antarctic region, and the Arctic as a place of relative stability," said David Hik, chief scientist at Polar Knowledge Canada, an agency focused on strengthening polar science and technology in Canada. "Now, both of those assumptions are being challenged." Fifty-eight countries, including Canada, are signatories to the Antarctic Treaty, which preserves the continent for scientific exploration and peace, and bans military and mining activity. But only half the signatories can vote on treaty business. Canada wants to secure voting rights as a so-called consultative party, and will make its case again at the Antarctic Treaty meeting in Milan, Italy, later this month. But there have been barriers to this. "Canada's claim to be a consultative party has been blocked, first and foremost, by Russia," said Klaus Dodds, a political biographer and Antarctic expert at Royal Holloway, University of London. "And the reason is, Russia wants its ally Belarus to be made a consultative party alongside Canada." WATCH | Who owns Antarctica? It's preserved for peace and science, for now: In March, a first-ever all-Canadian expedition sailed to Antarctica on HMCS Margaret Brooke, with 15 polar scientists hosted by the Canadian Navy. The Canadian Antarctic Research Expedition (CARE) 2025 mission conducted weeks of research and visited multiple countries' research stations on the continent, in part to raise Canada's profile at the southern pole. CBC News got exclusive access to the expedition. To capture the voyage CBC's international climate correspondent Susan Ormiston, producer Jill English and videographer Sam Martin spent a month aboard the Margaret Brooke broadcasting live via satellite, sending news of the voyage back to Canada. WATCH | How CBC's international climate team reported from a Navy ship in Antarctica: The polar regions are changing faster than other parts of the world, due to climate change. Antarctica's ancient glaciers are receding and sea ice reached near-record lows this year, both of which contribute to rising global sea levels. "The Antarctic ice sheet contains enormous amounts of fresh water, and as the ice sheet thins and melts in places, calves at faster rates, that's going to affect global sea level change," said Thomas James, chief scientist on the CARE 2025 mission. "What happens in Antarctica doesn't stay in Antarctica," he added. The southern ocean is a huge carbon sink and helps regulate the global climate. But warming ocean waters may disrupt those patterns, said Brent Else, co-scientific director at MEOPAR, which supports ocean research and training at Canadian universities. "As oceans warm as circulation patterns change, it's expected that ocean carbon sink will slow down over time. And the polar regions are the areas where those carbon sinks are most important," he said aboard HMCS Margaret Brooke. WATCH | Antarctic treasure — searching for climate clues in the Southern Ocean: Canada is a polar nation and, with rising concerns over sovereignty in the Arctic, the government is boosting military presence in the north. "Canada is, and forever will be, an Arctic nation, and we can never take our sovereignty and security in the region for granted," Prime Minister Mark Carney said on a visit to Iqaluit in March. A year ago, the Royal Canadian Navy began to plan a deployment to Antarctica to support scientific exploration and enhance its knowledge of geopolitical pressures at the southern pole. "We can see climate change in the North, we can see what China and Russia have been doing in and around the Canadian North, [and thinking] I wonder what's going on in the South Pole, and [can we] get the perspective and experience of the South American navies that are down here all the time," Vice-Admiral Angus Topshee told CBC News in an exclusive interview. The idea, he said, was to "do some science, and see if we can figure out things that can help us better protect and defend our own North." Topshee believes there are security concerns in Antarctica that threaten its stability. "I am concerned that the whole agreement that we would not [militarize and mine Antarctica] … would, could change. And I don't think that's in our interest to allow that to change easily." WATCH | Do polar security concerns extend to Antarctica? The Canadian Navy says yes: To voyage across the Antarctic Circle, HMCS Margaret Brooke sailed into some extreme weather and ice-clogged channels. As an Arctic and Offshore Patrol Vessel (AOPV), it is designed to break through new ice up to a metre thick. But with rapidly changing weather patterns, the ice moves and shifts, so that an open channel one day can be clogged with ice the next. An ice specialist from the Canadian Coast Guard, Donavan Tremblay, and an officer with the Chilean Navy, Javier Idiaquez, travelled with the Margaret Brooke crew to help chart a safe path. Even so, there were unexpected blockages, and navigating at night presented even more challenges. En route to Rothera Point beyond the Antarctic Circle, as the weather deteriorated and the ice encroached, Cmdr. Teri Share had to make a decision about whether to proceed. "It was a heightened level, absolutely," Share told CBC News from the captain's quarters on the Margaret Brooke. "We can take all the precautions that we can take. We can use all of the information that is provided to us. But still, there comes a point that it's on me as the commanding officer to say yes or no." In the end, Share made the call to push further south, with the crew threading the vessel through icebergs and sheet ice to reach Rothera Point, the ship's final destination, and the most southerly point the Canadian Navy had ever travelled. "It feels like just yesterday you and I were on the bridge, and you were asking me what [is the Navy] going to be doing down there, and what was I excited about," Share told the CBC's Susan Ormiston. "It's gone by really quickly," Share said, reflecting on the historic mission. WATCH | Blocked by ice in Antarctica, how the Royal Canadian Navy broke through: Watch full episodes of The National on CBC Gem, the CBC's streaming service.
TechCrunch
12 hours ago
- TechCrunch
Meet the Finalists: VivaTech's 5 Most Visionary Startups of 2025
Narrowing down the 30 most visionary startups of the year to just five finalists was no easy feat. VivaTech's Innovation of the Year attracted an extraordinary pool of applicants—startups tackling massive global challenges with bold, technically sophisticated, and scalable solutions. From redefining human-machine interaction to revolutionizing healthcare, climate, and infrastructure, each company brought something unique to the table. The selection process was intense, and every startup that made it to the top 30 should be incredibly proud of what they've built. VivaTech Innovation of the Year is debuting this year to celebrate and spotlight the trailblazing startups that are reshaping the future. This prestigious award is open to all exhibiting startups at VivaTech 2025 and recognizes one startup that has demonstrated exceptional creativity, technological ingenuity, and the potential to transform its industry. Now, we're excited to reveal the five finalists who will take the stage live at VivaTech 2025: BeyondMath: the world's first generative physics platform, replacing slow, expensive simulations with real-time, AI-powered physics. Engineers can run 1000x faster simulations, test thousands of designs instantly, and cut time, cost, and complexity. Chipiron: building the first light, low-cost MRI using ultra-low magnetic fields without sacrificing image quality. Their goal: make MRI 100x more accessible and enable early, large-scale screening—like a blood test for everyone. Enerdrape: offers the world's first non-invasive geothermal panels that transform underground spaces—like car parks and tunnels—into renewable heating and cooling sources, enabling fast, low-carbon retrofits without drilling in dense urban environments. Hua Tech International: an automated microfluidic platform integrating a nanostructured semiconductor biochip, multiplex fluorescence staining, and AI analysis to precisely capture, identify, and analyze rare circulating cells for cancer diagnostics. Techcrunch event Save $200+ on your TechCrunch All Stage pass Build smarter. Scale faster. Connect deeper. Join visionaries from Precursor Ventures, NEA, Index Ventures, Underscore VC, and beyond for a day packed with strategies, workshops, and meaningful connections. Save $200+ on your TechCrunch All Stage pass Build smarter. Scale faster. Connect deeper. Join visionaries from Precursor Ventures, NEA, Index Ventures, Underscore VC, and beyond for a day packed with strategies, workshops, and meaningful connections. Boston, MA | REGISTER NOW Lumisync: data centers to synchronize their data flow at the speed of light with the world's 1st 100% photonic oscillator to reduce their latency and energy consumption by 1000x. These standout companies will pitch their solutions during the Final of the VivaTech Innovation of the Year on Wednesday, June 11th at 1:35 PM, live on the Pitch Studio Stage. Each pitch will be followed by a Q&A session with a panel of expert judges including TechCrunch's own Jeff Taylor, Jaja Liao of 25madison, Shabir Vasram of Daphni and Howard Wright of NVIDIA. The winner of Innovation of the Year will be announced the following day at the VivaTech Global Awards Ceremony on Thursday, June 12th at 5:45 PM on Stage 1. In addition to the title, the winning startup will receive a free Startup Corner at VivaTech 2026 and a coveted spot in the TechCrunch Startup Battlefield 200. The Ceremony will also spotlight the four other VivaTech Awards and announce the winners of each. The Female Founder Challenge, celebrating the women leading innovative startups that are driving the disruptive technologies shaping the future. The Africatech Awards, this pan-African initiative recognizes and supports startups striving to make a positive impact in three important areas – GreenTech, HealthTech, and E-commerce / FinTech. The Next Startupper Challenge, the inter-school and university award for the new generation of entrepreneurs working on impactful projects to make their dreams a reality. The Tech For Change Award, launched this year alongside VivaTech Innovation of The Year, recognizing startups that place positive impact at the heart of their business model. Stay tuned—we can't wait to see these groundbreaking founders take the spotlight.
