SPACE/COSMOS
New Star Wars-like planet candidates with two suns discovered
A team of astronomers led by UNSW Sydney have piloted a new method to find planets – and in the process, found 27 potential new worlds in double star systems
University of New South Wales
image:
UNSW Sydney astronomers Scientia A/Prof. Ben Montet and Ms Margo Thornton.
view moreCredit: UNSW Media / Richard Freeman.
There’s so little we know about circumbinary planets – planets that orbit two stars instead of one – that they can feel like the stuff of fantasy.
And for good reason: to date, we’ve only confirmed the existence of 18 circumbinary planets, compared to the more than 6000 planets we know about in single star systems.
Even the most widely-known circumbinary planet is, quite literally, fiction: the desert planet Tatooine from Star Wars, aka the birthplace of Anakin Skywalker.
But a study led by UNSW has now detected 27 potential circumbinary planets in one sweep, using a new planet-finding method that broadens the typical type of planets we can find.
The findings are published today in the Monthly Notices of the Royal Astronomical Society, just in time for May the 4th, Star Wars Day.
“Most of our current knowledge on planets is biased, based on how we’ve looked for them,” says Ms Margo Thornton, lead author of the study, astronomer and PhD candidate at UNSW. “We’ve mostly found the easiest ones to detect.
“This new method could help us uncover a large population of hidden planets, especially those that don’t line up perfectly from our line of sight. It could help reveal what the true population of planets in our universe might look like.”
The planet-finding method, called apsidal precession, has been used to characterise binary stars before, but not in a large-scale search for planets.
It involves monitoring how the binary stars’ orbit of one other – made visible by their stellar eclipses – change over long periods of time.
If there’s a variation in their (normally predictable) eclipse schedule that can’t be explained by general relativity or stellar interactions, it means a third body could be influencing the stars’ orbits – and that body could be a planet.
The findings were made using data from NASA’s Transiting Exoplanet Survey Satellite (TESS), a space telescope launched in 2018 with the mission to search for exoplanets.
“I’m excited about the potential for how many planets we could find with this method,” says Scientia A/Prof. Ben Montet, astronomer and senior author on the study. “I wasn’t expecting to find 27 already at this point from the pilot study.
“Now we get to start the really fun project of figuring out which ones are real planets.”
A new way to find planets
Almost all planets have been discovered by the ‘transit’ method, which is when a planet crosses in front of its star, creating a mini-eclipse.
This eclipse causes a dip in the starlight signal sent to Earth, suggesting there might be a planet orbiting there.
But the transit method restricts us to only discovering planets that cross between Earth and their star. If a planet orbits its star (or stars, in this instance) at an irregular orbit, or an orbit that isn’t in our direct line of sight, it can slip under our radar.
“We’re missing a huge part of the architecture for these systems,” says A/Prof. Montet.
The new method helps astronomers detect planets like these that we might have otherwise missed – helping to build our knowledge of what type of environments can support planet development.
“With this method so far, we have 27 strong planet candidates in environments completely unlike our own solar system,” says Ms Thornton, who made these findings just one year into her PhD.
“By learning more about different types of planets, we can better understand how planets form and evolve, especially in these complex environments with two stars.”
The planets are called ‘candidates’ for now as the team need to confirm, or deny, their planet status using an additional observation method.
Ms Thornton has started work on this process and hopes to have a follow-up paper ready within the next year.
Our circumbinary neighbours
The planet candidates range from objects that could be as small as the mass of Neptune to 10x as large as the mass of Jupiter.
The closest is about 650 light years away from Earth, and the furthest about 18,000 away. To put this in perspective, one light year is 9.4 trillion kilometres.
“The candidates are scattered across both our southern and northern skies,” says A/Prof. Montet.
“This means that any time of the year, no matter when you’re looking, at least one of these star systems is out there visible for you to look towards – as long as you have a telescope.”
Even though the candidates stretch across immense distances, they’re still relatively close to our ‘neighbourhood’ in the Milky Way – although our list of circumbinary planet neighbours may soon be growing.
“We found 27 planet candidates out of 1590 binary star systems, which is an almost 2% rate of binary systems that could potentially host planets,” says A/Prof. Montet.
“That implies there could potentially be thousands, or tens of thousands, of possible planets to be found with data from the Vera C. Rubin Observatory’s new 10-year sky survey, the Legacy Survey of Space and Time.
“So it’s a really exciting first step – and it also shows that there’s going to be a lot of work to do over the next few years.”
Learning about other worlds
Most of the planets we know about in the universe are in single star systems, like our solar system.
But cosmically speaking, systems like ours are in the minority: more than half of the stars in the universe are in binary or multiple star systems.
“We’ve painted half a picture, and the other half of the canvas is completely blank,” says A/Prof. Montet.
Astronomers still have a lot of questions about planet formation in these systems – and this new planet-hunting method could help fill some of those knowledge gaps.
“We can start asking questions like how common these planets are overall and if they could be habitable,” says A/Prof. Montet.
“If circumbinary planets do turn out to be habitable, that means life could be anywhere. Life could be everywhere. The sheer numbers are really exciting.”
Ms Thornton says the search for other planets can help us learn more about our own place in the universe.
“Understanding the diversity of other worlds out there is the first step in understanding if anyone else is out there. If we are alone or not,” she says.
“That’s what a lot of this comes back to. We just want to understand where we came from, what our place looks like in the universe, and what else exists out there.”
From star gazer to space explorer
Ms Thornton spent a big part of her childhood on family camping trips, gazing up at the night sky.
She looks back on these moments as integral to her future in astronomy.
“I was always out under the stars and just always had questions that my parents couldn’t answer,” says Ms Thornton. “So, I wanted to be able to answer them.”
Now, many years and answered questions later, astronomy became a passion that she could pursue as a career.
“My supervisor Ben often talks about this moment in astronomy where you’re the only person in the world who’s seen evidence of something exciting,” says Ms Thornton.
“When the first system I looked at had a clear signal that these stars were precessing, and we were able to rule out all the other causes of it, we were left with these plots and numbers that suggested we might have just found a planet.
“For a little while, we were the only people on Earth who knew about it. It was a very exciting feeling – and it’s a great part of working in astronomy.”
Answering new galactic questions
Over the next few months, Ms Thornton will be studying the spectra of these binary stars – that is, the light that makes up these stars – using the Anglo Australian telescope in Coonabarabran. The telescope has a remote observing room accessible from UNSW Sydney’s campus.
The team will also be collaborating with researchers in the US, UK and China later in the year to learn more about the candidates visible from the Northern Hemisphere.
Studying the spectra can help the team rule out whether the bodies they detected could be higher mass objects, like stars, brown dwarfs, white dwarfs or even black holes.
If nothing else can explain the objects, they could be confirmed as planets.
In the meantime, the team are also planning on applying the same planet-searching method to larger samples, and running simulations to better understand how the planet candidates formed and how they might evolve over time.
“I was surprised by how effective the method was and how small of a signal we could pick up on using the TESS data,” says Ms Thornton. “There’s good promise this method could potentially help us find objects as small as Earth.
“I’m excited for what’s to come next with this project. The universe is a lot more complex than we can directly see, and there could be a lot more of these real-life Tatooines out there.”
Journal
Monthly Notices of the Royal Astronomical Society
Article Title
Detection of 27 candidate circumbinary planets through apsidal precession of eclipsing binaries observed by TESS
Article Publication Date
4-May-2026
Astronomers explore the surface composition of a nearby super-Earth
Webb observations constrain the properties of a rocky exoplanet’s hot crust
image:
This high-resolution photo of the planet Mercury probably resembles the rocky exoplanet LHS 3844 b. Results from JWST observations favour an airless rocky planet with a dark, basalt-like surface, likely space-weathered by irradiation and meteorite impacts.
view moreCredit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington (cropped) https://science.nasa.gov/photojournal/mercury-globe-0n-180e/
Using MIRI (Mid Infrared Instrument) on board the James Webb Space Telescope (JWST), a team of researchers led by former MPIA (Max Planck Institute for Astronomy, Heidelberg, Germany) PhD student Sebastian Zieba (Center for Astrophysics | Harvard & Smithsonian, Cambridge, USA) and Laura Kreidberg, MPIA Director and study PI (principal investigator), analysed the surface composition of the rocky exoplanet LHS 3844 b. Beyond characterizing exoplanetary atmospheres, this kind of deciphering the geological properties of planets orbiting distant stars is the next step in unveiling their nature. The results of this investigation are now published in the journal Nature Astronomy.
A dark and airless rocky super-Earth
LHS 3844 b is a rocky planet 30% bigger than Earth and orbits a cool red dwarf star once within roughly 11 hours. Whirling just three stellar diameters above the host star’s surface, the planet is tidally locked to its orbit. This means one rotation takes just as long as one revolution. As a result, the same hemisphere of LHS 3844 b always faces its star, producing a constant dayside with an average temperature of about 1000 Kelvin (approximately 725 Degrees Celsius or 1340 Degrees Fahrenheit). The LHS 3844 system is only 48.5 light-years (14.9 parsecs) away from Earth.
“Thanks to the amazing sensitivity of JWST, we can detect light coming directly from the surface of this distant rocky planet. We see a dark, hot, barren rock, devoid of any atmosphere.” – Laura Kreidberg, MPIA.
With its dark surface, LHS 3844 b may resemble a larger version of the Moon or the planet Mercury. This conclusion is based on analysing the infrared radiation received from the planet’s hot dayside. However, when measuring this radiation, we cannot see the planet directly; instead, we register the repeating change in brightness we receive from the star and the orbiting planet combined.
MIRI divided a portion of the planet’s infrared emission, ranging from 5 to 12 micrometres, into smaller wavelength sections and measured the brightness per wavelength bin. This is what astronomers call a spectrum, a rainbow-like distribution of the light’s components. Another data point, obtained from observations with the Spitzer Space Telescope and published a few years ago, augmented the analysis.
Constraining geological activity
Similar to how exoplanetary atmosphere research has benefited from climate science, this emerging field of exoplanetary geology draws on Earth-based geologic knowledge. Zieba, Kreidberg, and their collaborators ran models and accessed template libraries of rocks and minerals known from Earth, the Moon, and Mars to see what infrared signatures they would produce under the conditions on LHS 3844 b. Comparing observation-based data with these computations confidently ruled out a composition comparable to Earth’s crust, typically silicate-rich minerals such as granite.
Although this result is not very surprising – even in the Solar System, Earth is the only planet with such a crust – it may reveal details on LHS 3844 b’s geological history. Earth-like silicate-rich crusts are thought to form through a prolonged refinement process that requires tectonic activity and typically relies on water as a lubricant. The rocky material repeatedly melts and solidifies as it is mixed with mantle material, leaving the lighter minerals on the surface.
“Since LHS 3844 b lacks such a silicate crust, one may conclude that Earth-like plate tectonics does not apply to this planet, or it is ineffective,” says Sebastian Zieba. “This planet likely only contains little water.”
What can we deduce about the exoplanet’s rocky surface?
Instead, the dark surface points to a composition reminiscent of terrestrial or lunar basalt, or of Earth’s mantle material. However, the astronomers attempted an even more detailed characterization.
A statistical analysis of how well this spectrum fits various mineral mixtures and configurations revealed that extended solid areas of basalt or magmatic rock best match the observations. They are rich in magnesium and iron and can include olivine. Crushed material, such as rocks or gravel, also fits fairly well, whereas grains or powders are inconsistent with the observations due to their brighter appearance, at least at first glance.
Without a protective atmosphere, planets are subjected to space weathering, predominantly driven by hard, energetic radiation from the host star and impacts from meteorites of various sizes.
“It turns out, these processes not only slowly dissolve hard rocks into regolith, a layer of fine grains or powder as found on the Moon,” explains Zieba. “They also darken the layer by adding iron and carbon, making the regolith’s properties more consistent with the observations.”
Geologically fresh or weathered? Two possible scenarios
This assessment left the astronomers with two scenarios for the planet’s surface that match the data equally well. One involves a surface dominated by dark, solid rock composed of basaltic or magmatic minerals. Compared to geological timescales, space weathering alters its properties quickly. Therefore, the astronomers conclude that, in this scenario, the surface should be relatively fresh, produced by recent geological activity, such as widespread volcanism.
The second scenario also proposes a dark surface, comparable to the Moon or Mercury. Still, it accounts for prolonged space weathering, which leads to extended regions covered by a darkened regolith layer, a fine powder also present on the Moon, as evidenced by the iconic photos of the astronauts’ footprints. This alternative relies on longer periods of geological inactivity, thereby requiring conditions opposite to the first scenario.
Attempts to resolve the ambiguity
These two alternatives differ in the degree of recent geological activity required. On Earth and other active objects in the Solar System, a typical phenomenon during such activity is outgassing. Sulphur dioxide (SO2) is a gas commonly connected to volcanism. If present on LHS 3844 b in reasonable amounts, MIRI should have detected it. Still, it found nothing. Therefore, a recent period of activity seems unlikely, which leads the astronomers to favour the second scenario. If correct, LHS 3844 b may truly look much like Mercury indeed.
In order to test their idea, Zieba, Kreidberg, and their colleagues are already pursuing a more direct approach. They have obtained additional JWST observations, which should enable them to discern surface conditions by exploiting small differences in how solid slabs and powders emit or reflect light. The distribution of emission angles depends on surface roughness, which affects the amount of radiation received at a given viewing angle. This concept is successfully applied to characterizing asteroids in the Solar System. “We are confident the same technique will allow us to clarify the nature of LHS 3844 b’s crust and, in the future, other rocky exoplanets,” concludes Kreidberg.
Additional information
Laura Kreidberg is the only MPIA astronomer involved in this study.
Other researchers were: Sebastian Zieba (Center for Astrophysics | Harvard & Smithsonian, Cambridge, USA), Brandon P. Coy (Department of the Geophysical Sciences, University of Chicago, USA), Aaron Bello-Arufe (Jet Propulsion Laboratory, California Institute of Technology, Pasadena, USA [JPL]), Kimberly Paragas (Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, USA), Xintong Lyu (Peking University, Beijing, China), Renyu Hu (The Pennsylvania State University, University Park, USA and JPL), Aishwarya Iyer (NASA Goddard Space Flight Center, Greenbelt, USA), Kay Wohlfarth (Technische Universität Dortmund, Germany)
The JWST observations used in this study were conducted as part of GO program #1846 (PI: Laura Kreidberg, co-PI: Renyu Hu) titled “A Search for Signatures of Volcanism and Geodynamics on the Hot Rocky Exoplanet LHS 3844 b.”
The MIRI consortium comprises the ESA (European Space Agency) member states: Belgium, Denmark, France, Germany, Ireland, the Netherlands, Spain, Sweden, Switzerland, and the United Kingdom. National science organisations fund the consortium’s work – in Germany, the Max Planck Society (MPG) and the German Aerospace Center (DLR). Participating German institutions include the Max Planck Institute for Astronomy in Heidelberg, the University of Cologne, and Hensoldt AG in Oberkochen, formerly Carl Zeiss Optronics.
The James Webb Space Telescope is the world’s leading observatory for space research. It is an international programme led by NASA and its partners ESA and CSA (Canadian Space Agency).
The Spitzer Space Telescope was operated by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA.
Journal
Nature Astronomy
Method of Research
Observational study
Subject of Research
Not applicable
Article Title
The dark and featureless surface of rocky exoplanet LHS 3844 b from JWST mid-infrared spectroscopy
Article Publication Date
4-May-2026
Outer solar system object has an atmosphere but shouldn’t
National Institutes of Natural Sciences
image:
Artist’s conception of this research showing an imagined time sequence as a star passes behind a TNO with an atmosphere.
view moreCredit: NAOJ
A team of professional and amateur Japanese astronomers found evidence for a thin atmosphere around a small body in the outer Solar System. The object is so small that it should not have a sustainable atmosphere, raising questions about when and how the atmosphere formed. Future observations to better characterize the atmosphere will help solve these mysteries.
In the cold reaches of the outer Solar System lie thousands of small objects known as trans-Neptunian objects (TNOs) because they lie outside the orbit of Neptune. A thin atmosphere has been observed around Pluto, the most famous TNO, but studies of other TNOs have yielded negative results. Most TNOs are so cold, and their surface gravity so weak, that they are not expected to retain atmospheres.
But astronomers like to expect the unexpected, so they took advantage of a lucky “natural experiment” to look for an atmosphere around a TNO known as (612533) 2002 XV93. This object, abbreviated as 2002 XV93, has a diameter of approximately 500 km. For reference, Pluto’s diameter is 2,377 km. The orbit of 2002 XV93 is such that, as seen from Japan, it passed directly in front of a star on January 10, 2024. As the star disappears behind 2002 XV93, it might gradually fade, indicating that the light is being attenuated as it passes through a thin atmosphere; or it might suddenly wink out as it slips behind the solid surface of the TNO.
A team of professional and amateur astronomers, led by Ko Arimatsu at NAOJ Ishigakijima Astronomical Observatory, observed the star as 2002 XV93 passed in front of it from multiple sites in Japan. The obtained data are consistent with attenuation by an atmosphere.
Calculations show that the atmosphere found around 2002 XV93 is expected to last less than 1000 years unless it is replenished. So it must have been created or replenished recently. Observations by the James Webb Space Telescope show no signs of frozen gases on the surface of 2002 XV93 that might sublimate to form an atmosphere. One possibility is that some event brought frozen or liquid gases from deep inside the TNO to the surface. Another possibility is that a comet crashed into 2002 XV93, releasing gas that formed a temporary atmosphere. Further observations are needed to distinguish between these two scenarios.
Journal
Nature Astronomy
Method of Research
Observational study
Subject of Research
Not applicable
Article Title
Detection of an atmosphere on a trans-Neptunian object beyond Pluto
Article Publication Date
4-May-2026
Non-rotating early galaxy is a surprise to astronomers
University of California - Davis
Astronomers using the James Webb Space Telescope have made a surprising discovery about a galaxy long, long ago and far, far away: It isn’t rotating.
That’s something only seen in the most massive, mature galaxies that are closer to us in space and time, said Ben Forrest, a research scientist in the Department of Physics and Astronomy at the University of California, Davis, and first author on the paper published May 4 in Nature Astronomy.
“This one in particular did not show any evidence of rotation, which was surprising and very interesting,” Forrest said.
According to current theories, as the first galaxies formed, angular momentum from inflowing gas and the influence of gravity set them spinning.
Over many billions of years, some galaxies, especially those within galaxy clusters, merged with each other multiple times and their combined rotations added to or partly canceled each other. That’s why some galaxies that are closest to Earth (and therefore also relatively recent) can show little overall rotation but a lot of random movement of stars within them.
This process should take an enormously long time, so it’s surprising that galaxy XMM-VID1-2075 had achieved this state when the universe was less than 2 billion years old.
Forrest and colleagues in the MAGAZ3NE (Massive Ancient Galaxies at z>3 NEar-Infrared) survey had previously observed this galaxy with the W.M. Keck observatory in Hawaiʻi.
“Previous MAGAZ3NE observations had confirmed this was one of the most massive galaxies in the early universe, with already several times as many stars as our Milky Way, and also confirmed that it was no longer forming new stars, making it a compelling target for follow-up observations,” Forrest said.
Pushing the frontiers
The team used the James Webb Space Telescope to take a closer look at XMM-VID1-2075 and two other galaxies of similar age. They were able to measure the relative movement of material inside them.
“This type of work has been done a lot with nearby galaxies because they're closer and larger and so you can do these kinds of studies from the ground, but it's very difficult to do with high redshift galaxies because they appear a lot smaller in the sky,” Forrest said. “(James Webb Space Telescope) is really pushing the frontier for these kinds of studies.”
Of the three galaxies they sampled, one is clearly rotating, one is “kind of messy,” and one has no rotation but a lot of random motion, Forrest said. “That’s consistent with some of the most massive galaxies in the local universe, but it was a bit surprising to find it so early on.”
How did this galaxy become a “slow rotator” in less than 2 billion years? One possibility is that it is the result not of multiple mergers, but a single collision between two galaxies rotating pretty much in opposite directions. That idea is supported by the team’s observations.
“For this particular galaxy, we see a large excess of light off to the side. And so that's suggestive of some other object which has come in and is interacting with the system and potentially changing its dynamics,” Forrest said.
The astronomers are continuing to look for other, similar objects in the early universe. By comparing their observations with simulations, they can test theories about galaxy formation.
“There are some simulations that predict that there will be a very small number of these non-rotating galaxies very early in the universe, but they expect them to be quite rare. And so this is one way in which we can test these simulations and really figure out how common they are, and that can then give us information about whether our theories of this evolution are correct,” Forrest said.
Additional coauthors on the paper are: Brian C. Lemaux, UC Davis and Gemini Observatory, Hawaiʻi; Adam Muzzin and Adit H. Edward, York University, Toronto; Danilo Marchesini, Richard Pan and Nehir Ozden, Tufts University; Jacqueline Antwi-Danso, University of Toronto; Wenjun Chang, UC Riverside; M. C. Cooper and Stephanie M. Urbano Stawinski, UC Irvine; Percy Gomez, W. M. Keck Observatory, Kamuela, Hawaiʻi; Lucas Kimmig and Rhea-Silvia Remus, Ludwig-Maximilians-Universität München, Germany; Ian McConachie, University of Wisconsin-Madison; Allison Noble, Arizona State University; and Gillian Wilson and M. E. Wisz, UC Merced.
The work was supported by grants from NASA, the Space Telescope Science Institute and National Science Foundation.
Journal
Nature Astronomy
Method of Research
Experimental study
Subject of Research
Not applicable
Article Title
A massive and evolved slow-rotating galaxy in the early Universe
Article Publication Date
4-May-2026
Giant planet’s slimmer profile
New research measures Jupiter’s dimensions with unprecedented precision
For over 50 years, we thought we knew the size and shape of Jupiter, the solar system’s largest planet. Now, Weizmann Institute of Science researchers have revised that knowledge using new data and technology.
In a new study published today in Nature Astronomy, Weizmann scientists, who led an international team from Italy, the US, France and Switzerland, provide the most precise determination yet of Jupiter’s size and shape.
“Just by knowing the distance to Jupiter and watching how it rotates, it’s possible to figure out its size and shape,” says Prof. Yohai Kaspi of Weizmann’s Earth and Planetary Sciences Department. “But making really accurate measurements calls for more sophisticated methods.”
“Jupiter’s shape, as understood until now, was derived by researchers from just six measurements made almost five decades ago by NASA’s Voyager and Pioneer missions, which sent radio beams from the spacecraft to Earth,” explains Dr. Eli Galanti, a senior staff scientist who led the research in Kaspi’s team. “Those missions provided a foundation, but now we got the rare opportunity to spearhead the analysis of as many as 26 new measurements made by NASA’s Juno spacecraft.”
Launched in 2011 and orbiting Jupiter since 2016, Juno has been sending back to NASA streams of raw data. When NASA extended the mission in 2021 so the spacecraft could keep studying Jupiter and its moons more closely, Juno’s new expanded path placed the spacecraft in an orbit that allowed it to pass behind Jupiter from Earth’s point of view, something its earlier orbit never did. “Juno’s passing behind Jupiter provides an opportunity for new science objectives. When the spacecraft passes behind the planet, its radio communication signal is blocked and bent by Jupiter’s atmosphere. This enables an accurate measurement of Jupiter’s size,” says Juno’s Principal Investigator Dr. Scott J. Bolton of Southwest Research Institute in San Antonio, Texas.
The Juno team at Weizmann seized this new opportunity. “We tracked how the radio signals bend as they pass through Jupiter’s atmosphere, which allowed us to translate this information into detailed maps of Jupiter’s temperature and density, producing the clearest picture yet of the giant planet’s size and shape”, says Maria Smirnova, a PhD student in Kaspi’s group, who developed a special technique to process Juno’s new data.
The new findings show that Jupiter is slightly smaller than previously estimated – it’s about 8 km less wide at the equator and 24 km flatter at the poles. In other words, it’s more flattened compared to previous assessments. “Textbooks will need to be updated,” Kaspi says. “The size of Jupiter hasn’t changed, of course, but the way we measure it has.”
“These few kilometers matter,” Galanti explains. “Shifting the radius by just a little lets our models of Jupiter’s interior fit both the gravity data and atmospheric measurements much better.” This implication was tested by another PhD student in Kapsi’s group, Maayan Ziv. “We were in a unique position to use our state-of-the-art models for the interior density structure of Jupiter to show that the refined shape helps bridge the gap between the models and the measurements,” Ziv says. This study also has broader implications for understanding the structure of gas planets in general, since Jupiter serves as a standard reference for the study of gas giants within the solar system and beyond.
Kaspi notes also that earlier measurements didn’t account for Jupiter’s powerful winds. By including these extreme winds in their calculations, the Weizmann team cleared up long-standing discrepancies in earlier measurements. “It’s difficult to see what’s happening beneath the clouds of Jupiter, but the radio data give us a window into the depth of Jupiter’s zonal winds and powerful hurricanes,” Kaspi explains.
The work on the winds ties into a recent study by Kaspi and Dr. Nimrod Gavriel, a graduate of Kaspi’s group, on Jupiter’s vast polar cyclones. That study, published in PNAS, used Juno measurements of these cyclones’ motion to predict how deep into the interior they extend. Overall, an improved understanding of Jupiter’s winds enables scientists to elucidate the relation between the planet’s atmosphere and its deep interior. Their prediction was recently confirmed by microwave measurements made by the Juno spacecraft.
“This research helps us understand how planets form and evolve,” Kaspi says. “Jupiter was likely the first planet to form in the solar system, and by studying what’s happening inside it, we get closer to understanding how the solar system, and planets like ours, came to be.”
Looking into the future, the techniques developed in these studies will serve the team during their analysis of data from the European Space Agency’s unmanned spacecraft JUICE, launched in 2023. The mission carries a Weizmann-designed instrument that will allow a deeper view into the planet’s atmosphere.
Also participating in the study were Matteo Fonsetti, Andrea Caruso, Paolo Tortora and Marco Zannoni from the University of Bologna, Italy; Dustin R. Buccino, Steven M. Levin, Marzia Parisi and Ryan S. Park from the Jet Propulsion Laboratory, California Institute of Technology, USA; William B. Hubbard from the University of Arizona, USA; Burkhard Militzer from the University of California, Berkeley, USA; Tristan Guillot from the Observatoire de la Côte d’Azur, France; Ravit Helled from the University of Zürich, Switzerland; Paul Steffes from the Georgia Institute of Technology, USA; and Paul Withers from Boston University, USA.
Prof. Yohai Kaspi’s research is supported by the Helen Kimmel Center for Planetary Science; the Knell Family Institute of Artificial Intelligence; and the Brenden-Mann Women’s Innovation Impact Fund.
The Juno mission is managed by NASA's Jet Propulsion Laboratory, a division of Caltech in Pasadena, California, for the agency's Science Mission Directorate in Washington.
For more information about the Juno mission, visit https://www.nasa.gov/juno and https://missionjuno.swri.edu.
Space logistics on the right track
Researchers publish a new method for plotting routes through space and time
image:
An illustrative diagram of a space probe mission: from Earth, the probe follows several transfer trajectories to reach different asteroids in succession. Launch and arrival times are precisely calculated and coordinated based on the respective astrodynamic conditions.
view moreCredit: Isaac Rudich
How does one plan a space mission that involves visiting multiple celestial bodies which are constantly moving? Researchers at Bielefeld University have, for the first time, developed a precise mathematical approach to this problem. The publication in a leading international journal demonstrates that decision-support methods at the interface between economics and mathematics can advance space travel and transport planning – with implications extending far beyond space missions.
Key facts at a glance:
• An international team, including researchers from Bielefeld University, has developed the first precise solution to a highly complex problem in space logistics.
• The results were published in INFORMS Journal on Computing, a leading international journal.
• The method could help make not only space missions, but also transportation and logistics systems on Earth more efficient in the future.
A new scientific publication from Bielefeld University sets a benchmark in optimization research. Together with an international team, Professor Michael Römer from the Faculty of Business Administration and Economics has developed a mathematical framework that solves a complex problem from space logistics exactly for the first time: the optimal planning of a route to visit several asteroids under conditions that are as close to reality as possible.
At the center of the research is the so-called Asteroid Routing Problem. It addresses the question: In what order should a spacecraft visit multiple asteroids if both travel time and fuel consumption are to be minimized? The challenge is that, unlike in classical routing problems, the travel time between destinations is constantly changing because all celestial bodies are in continuous motion.
From an ESA idea to a top-tier publication
The idea for the study originated in Bielefeld, sparked by a success in a competition organized by the European Space Agency (ESA). During a research stay in Bielefeld, lead author Isaac Rudich revisited the topic and, together with the team, developed a new solution approach.
The researchers used so-called Decision Diagrams—graphical optimization models that systematically structure very large sets of possible solutions. Combined with a specialized search method that narrows down promising solutions efficiently, the team was able to compute exact solutions to this problem for the first time.
A particularly challenging component involved a subproblem from celestial mechanics known as the Lambert problem. It describes how to calculate an optimal trajectory between two moving objects. Because this calculation must be repeated for every possible route, the overall problem had previously been considered extremely difficult to solve.
Relevance far beyond space exploration
The social significance extends far beyond the space industry, as many real-world planning problems operate in a similar way: in the case of bus routes, supply chains or shipping routes, too, journey times often depend on the departure time, because factors such as weather or traffic volumes change dynamically. The calculations involved are often very complex. The new approach could help make such systems more efficient and robust in the future. This has implications for mobility, supply systems, and sustainability. In tests, the method delivered not only multiple provably optimal solutions, but also new benchmark values that can guide future research.
Statement by Professor Michael Römer
“This work is special because it combines a scientific breakthrough with strong future potential. We have not only solved a long-standing open problem exactly for the first time, but also shown that our methods can generate impulses for space exploration, logistics, and public transport. It is precisely this connection between fundamental research and societal application that makes this publication so relevant.”
Journal
INFORMS Journal on Computing
Method of Research
Computational simulation/modeling
Subject of Research
Not applicable
Article Title
An Exact Framework for Solving the Space-Time Dependent TSP
The DAMPE satellite sheds light on the origin of cosmic rays
The international cosmic ray observation mission, including UNIGE, reveals a key feature of these particles, marking a major breakthrough in understanding their origin.
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Cosmic rays are primarily composed of protons, but also of helium, carbon, oxygen, and iron nuclei.
view moreCredit: © Chinese Academy of Science
A century after their discovery, cosmic rays—particles of extreme energy originating from the far reaches of the universe—remain a mystery to scientists. The DAMPE (Dark Matter Particle Explorer) space telescope is tackling this phenomenon, particularly investigating the role that dark matter may play in their formation. This international mission, which includes the University of Geneva (UNIGE), has made a major breakthrough by highlighting a universal feature of these particles. The results are published in the journal Nature.
Cosmic rays are the most energetic particles observed in the universe, far surpassing the energies of particles produced by man-made accelerators on Earth. Their exact origin is still under study, and it is believed that they originate from extreme astrophysical phenomena, such as supernovae, black hole jets, or pulsars.
The DAMPE space telescope, launched in December 2015, aims to provide answers regarding the origin and nature of these cosmic rays. This space mission, with the astrophysics group from the Department of Nuclear and Particle Physics (DPNC) at the University of Geneva (UNIGE) being one of its main contributors, has made a crucial breakthrough. Through the analysis of high-precision measurements collected by the telescope, scientists have identified a universal feature in the energy spectra of primary cosmic ray nuclei, ranging from protons to iron.
"Cosmic rays are primarily composed of protons, but also of helium, carbon, oxygen, and iron nuclei,’’ explains Andrii Tykhonov, associate professor at the DPNC in the Faculty of Science at UNIGE, and co-author of the study. "These particles are also categorised according to their energy: low, up to a few billion electron-volts; intermediate, from a few billion to several hundred billion electron-volts; and high, from 1,000 billion electron-volts and beyond."
A New Common Feature
The results show that, for all the nuclei studied, the number of particles decreases more and more rapidly beyond a certain value. This phenomenon is called "spectral softening". Normally, the number of particles already decreases as energy increases, but here, this decrease becomes even more pronounced. This occurs around a rigidity of about 15 TV (teraelectron-volts). The rigidity of a particle measures the resistance of its trajectory to a magnetic field. The observation of a common structure at this rigidity strongly supports models that explain that the acceleration and transport of cosmic rays depend on the particles' rigidity. In contrast, alternative models, which suggest that energy per nucleon (energy divided by the number of nucleons in the particle) is a key factor, are strongly ruled out by these measurements, with a confidence level of 99.999%.
The Geneva team played a central role in this scientific breakthrough. They notably developed advanced artificial intelligence techniques for reconstructing the detected events and contributed to key measurements of proton and helium fluxes, as well as to the analysis of carbon. The group also led the development of one of DAMPE's major sub-detectors, the Silicon-Tungsten Tracker (STK), an essential instrument for the precise reconstruction of particle trajectories and the measurement of their charge.
These results represent a significant step towards a more comprehensive understanding of the origin of cosmic rays and the mechanisms that govern their propagation in the galaxy. They provide new experimental constraints on acceleration models in astrophysical sources and on the transport of particles in the interstellar medium, paving the way for a more accurate description of high-energy particle populations.
Journal
Nature
Method of Research
News article
Subject of Research
Not applicable
Article Title
Charge-dependent spectral softenings of primary cosmic rays below the knee
Shadowed cold traps could unlock the mystery of lunar ice
New evidence suggests that ice has been accumulating on the Moon for 1.5 billion years – and reveals the most promising places to find it
More than half a century after the last crewed landing, a new lunar space race is underway – with last week’s launching of NASA’s Artemis II mission and the United States, Russia and China all aiming to establish permanent bases on the Moon. Unlike the Apollo program, during which American astronauts landed at six different sites on the lunar surface, 21st-century missions are all focused on a single location: the Moon’s South Pole. Spaceflight pioneer Robert H. Goddard proposed over a century ago that ice deposits might exist at the lunar poles, and indirect evidence collected over the past 20 years has lent support to this hypothesis. In space exploration, ice is a highly sought-after resource: It can be processed into water for drinking and irrigation, split into rocket fuel for deep-space travel and even used to study the history of celestial bodies.
Now, researchers from the Weizmann Institute of Science, together with collaborators in the United States, have uncovered new scientific evidence showing that ice has been gradually accumulating on the Moon’s poles for at least 1.5 billion years. Their new study, published today in Nature Astronomy, identifies ancient “cold traps” on the lunar surface and designates them as prime targets for future missions.
Unlike Earth, whose tilted axis causes the Sun’s position in the sky to change throughout the year, the Moon has almost no tilt, and the Sun is always positioned approximately above its equator. If you were standing at one of the lunar poles, you would see the Sun staying close to the horizon as it completes a monthly cycle rather than rising and setting as it does on Earth. As a result, sunlight cannot reach and warm the deep, steep craters at the lunar poles, which are known as “permanently shadowed regions.”
This was not always the case. In the distant past, the Moon had a much greater axial tilt, but over the last several billion years it has been straightening up. In 2023, researchers showed that as the Moon’s tilt decreased, more and more craters near the poles became permanently shadowed, and cooled dramatically. By calculating when each crater lost its exposure to sunlight, they were able to deduce the “age” of each permanently shadowed region.
In the new study, Prof. Oded Aharonson of Weizmann’s Earth and Planetary Sciences Department and his collaborators – Prof. Paul Hayne of the University of Colorado Boulder and Dr. Norbert Schörghofer of the Planetary Science Institute in Honolulu – set out to examine whether there is a connection between the age of a permanently shadowed region and the proportion of its area covered by ice.
Ice reflects more ultraviolet light at certain wavelengths than the Moon’s rocky surface, making it possible to infer where it is located. Ultraviolet light provides an advantage because it emanates not only from the Sun but also from distant stars, and it can enter permanently shadowed areas. The researchers analyzed data collected by an ultraviolet-sensitive instrument aboard NASA’s Lunar Reconnaissance Orbiter, which has been orbiting and mapping the Moon since 2009.
A 3-D animation showing permanently shadowed craters (white and light blue) near the Moon’s South Pole (black arrow), considered promising locations for finding water ice. Scientists have discovered evidence that these cold traps have been accumulating water ice (violet) for at least 1.5 billion years – but not all are equally effective. The well-known Shackleton Crater (closest to the South Pole) has been too warm for much of lunar history to collect ice. In contrast, Haworth Crater (the one with the greatest expected ice coverage) has acted as an efficient ice trap for billions of years – and was therefore identified as a prime target for future landed missions. The animation is based on data from the Lunar Orbiter Laser Altimeter and the Lyman-Alpha Mapping Project on board NASA's Lunar Reconnaissance Orbiter
“We found that the earlier a region became shadowed, the larger the area that was able to accumulate ice,” says Aharonson. “This trend began at least 1.5 billion years ago and has continued even over the past 100 million years. This suggests that ice has been building up on the Moon from a nearly continuous source – or sources – rather than through a single event such as a large comet impact.”
For ice not only to form on the lunar surface but also to persist for hundreds of millions or even billions of years without evaporating, extremely low temperatures are required – around minus 160 degrees Celsius. Regions that maintain such temperatures year-round are known as cold traps. While many permanently shadowed regions qualify as cold traps, some do not, because surrounding walls can radiate heat into the crater.
To identify the most promising locations for finding lunar ice, the researchers used geometric calculations to determine which permanently shadowed regions also function as cold traps, and when in the Moon’s history they acquired this status.
“The longer a given region has been a cold trap, the more ice it has accumulated,” Aharonson explains. “In most cases, a crater became shadowed and turned into a cold trap at the same time – but not always. For example, Shackleton Crater has been shadowed for about 3.5 billion years and was considered a promising site in the search for lunar ice. We discovered, however, that it only became a cold trap around 500 million years ago. To identify targets for future missions, we searched for the oldest cold traps and found several extensive ones more than 3.3 billion years old near the Moon’s South Pole.”
These findings are especially significant since locating and sampling lunar ice is one of the primary goals of NASA’s future crewed Artemis missions, scheduled to land astronauts at the Moon’s South Pole. NASA’s long-term vision includes establishing a permanent lunar base to serve as preparation – and possibly a transit station – for future crewed missions to Mars.
“The gold-standard proof of the existence of ice on the Moon would be a sample of it,” says Aharonson. “It would allow us to compare the chemical composition of water on the Moon with that on Earth, and to assess whether – and how – crewed lunar missions could make use of this resource.”
The study supplies motivation for follow-up exploration of the most ancient cold traps and provides guidance on the best locations to target, such as Haworth Crater, one of the newly identified ancient cold traps. “Future spacecraft missions would be able to collect extensive data on the ice from the crater’s surface, and rovers would be able to approach, enter and sample the ice deposits,” says Hayne.
The origins of lunar ice
Although the origin of lunar water remains unresolved, the researchers built a simple mathematical model to explore various possibilities. According to the model, the amount of ice on the Moon’s surface is affected by three processes: water supply, evaporation and what’s known as impact gardening – a process in which the disturbance of lunar soil and rocks redistributes ice and buries it beneath the surface.
The observation that relatively little ice is found in younger cold traps, combined with the slow accumulation of ice over hundreds of millions of years, led the researchers to conclude that both water supply and water loss on the Moon occur at relatively rapid rates, like a faucet filling a leaking bucket.
One proposed source of lunar water is that volatile water from the Moon’s interior reaches the surface through volcanic activity. Another possible source is solar wind: a stream of hydrogen atoms capable of taking part in chemical reactions on the lunar surface to form water. A third option is asteroid and comet impacts – not a single catastrophic event, but multiple impacts occurring every few million years.
“Finding water beyond Earth in liquid and usable form is one of the most important challenges in astronomy,” Aharonson says. “Planned lunar missions may help us determine the origin of water on the Moon – but they could also teach us much more. As Earth’s natural satellite, the Moon is an excellent laboratory for studying the history of our planet and its water. Moreover, we may gain insights into the composition and distribution of water that could be waiting for us on more distant planets and moons we have yet to visit.”
Journal
Nature Astronomy
Article Title
Observational constraints on the history of lunar polar ice accumulation
The most common planets in the galaxy don’t appear around the most common stars
image:
Erik Gillis, a PhD student in McMaster University’s Department of Physics and Astronomy, is lead author of a new study revealing that the most common planets in our galaxy don't exist around the most common stars.
view moreCredit: Erik Gillis
Hamilton, ON, April. 29 2026–Astronomers now estimate there is at least one planet for every star in our galaxy. These worlds, called exoplanets, are planets that orbit stars outside our solar system. But new research from McMaster University reveals a surprising twist: the most common planets in our galaxy don’t exist around the most common stars.
Around stars like our Sun, the most common planets are sub-Neptunes – worlds thought to resemble Neptune but smaller in size – and super-Earths, rocky planets that are up to ten times more massive than Earth. For nearly a decade, astronomers have known that these two types of planets are widespread around Sun-like stars across the galaxy. But Sun-like stars make up only a minority of the stars in our galaxy, leaving a gap in our understanding of how planets form.
To fill that gap, McMaster researchers examined planets orbiting mid-to-late M dwarfs. These are small stars, just eight to 40 per cent the size of our Sun, that make up most of the stars in the Milky Way. Because of their faintness, these stars have historically been difficult to study.
NASA’s Transiting Exoplanet Survey Satellite (TESS) has changed that. By observing a new patch of sky every 28 days, the satellite surveys the entire sky over 26 months, providing an unparalleled view of these stars and the planets that orbit them.
Using the TESS data, the McMaster team discovered that around mid-to-late M dwarfs, sub-Neptunes almost completely disappear. These stars host many super-Earths but virtually no sub-Neptunes, challenging existing theories of planet formation.
“We didn’t just refine the picture – we changed it. Around these stars, sub-Neptunes effectively vanish, which means the mechanisms shaping planets here are different,” says Erik Gillis, a PhD student in the Department of Physics and Astronomy. Gillis conducted the work under the supervision of Ryan Cloutier, assistant professor and Canada Research Chair in Exoplanetary Astronomy.
Astronomers have long attributed the distinction between super-Earths and sub-Neptunes to photoevaporation, a process where intense starlight strips away a planet’s atmosphere. Mid-to-late M dwarfs are extremely active and should be capable of evaporating planetary atmospheres efficiently, but not to the extent we're seeing here, explains Gillis. The fact that sub-Neptunes exist in such small numbers around these stars suggests that planet formation here may favour water-rich worlds rather than gas-shrouded sub-Neptunes.
“If we want to understand the origins of planets and the origins of life, we need a complete picture of how planets form and what they’re made of. This research brings us closer to that,” says Gillis.
The findings, published today in The Astronomical Journal, come at a time when exoplanet science is growing rapidly. The first exoplanets were discovered just 30 years ago – a blink of an eye compared to some other astronomical fields.
Since then, we’ve only been able to study a small slice of the universe to build a picture of planetary systems. We assume these patterns hold everywhere because the same physical processes shape planets across the galaxy.
“Our solar system was once the only example we had. Now, thanks to missions like TESS, we can compare thousands of systems and uncover patterns that rewrite our assumptions,” says Cloutier.
“It was already astonishing to learn that the most common planets in our galaxy do not exist within our own solar system. Now with this recent work we're developing a clearer picture of where these super-Earths and sub-Neptunes come from.”
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Journal
The Astronomical Journal
Article Title
TESS Planet Occurrence Rates Reveal the Disappearance of the Radius Valley Around Mid-to-late M Dwarfs
Article Publication Date
29-Apr-2026
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