March 8, 2026
By Eurasia Review
About 15% of asteroids near Earth have small moons orbiting them, making binary asteroid systems common in our cosmic neighborhood.
Now, a team of astronomers led by the University of Maryland discovered that these binary asteroid systems are far more dynamic than anyone realized—actively exchanging rocks and dust in gentle, slow-motion collisions that reshape them over millions of years.
After analyzing images taken by NASA’s Double Asteroid Redirection Test (DART) spacecraft in 2022, just before its deliberate collision with asteroid moon Dimorphos, the team identified bright, fan-shaped streaks across the moon’s surface—the first direct visual evidence of material naturally traveling from one asteroid to another. The researchers’ findings, published in The Planetary Science Journal, have significant implications for understanding asteroids that could potentially threaten Earth.
“At first, we thought something was wrong with the camera, and then we thought it could’ve been something wrong with our image processing,” said the paper’s lead author Jessica Sunshine, a professor with joint appointments in the Department of Astronomy and Department of Geological, Environmental, and Planetary Sciences at UMD. “But after we cleaned things up, we realized the patterns we were seeing were very consistent with low velocity impacts, like throwing ‘cosmic snowballs.’ We had the first direct proof for recent material transport in a binary asteroid system.”
The team’s findings also provided the first visual confirmation of the Yarkovsky-O’Keefe-Radzievskii-Paddak (YORP) effect, in which sunlight makes small asteroids spin faster until material flies off their surfaces, sometimes creating moons. Sunshine noted that this was likely the case for Didymos and its smaller moon Dimorphos, as evidenced by the traces of ‘cosmic snowballs’ left on Dimorphos’ surface.
Finding these traces required months of detective work. The fan-shaped streaks were invisible in the DART spacecraft’s original images, but UMD astronomy research scientist Tony Farnham and former postdoctoral researcher Juan Rizos helped develop sophisticated techniques to remove boulder shadows and lightning effects from the pictures, revealing the surprising streaks that ‘cosmic snowballs’ left behind.
“We ended up seeing these rays that wrapped around Dimorphos, something nobody’s ever seen before,” Farnham said. “We couldn’t believe it at first because it was subtle and unique.”
For the researchers, the DART mission’s trajectory created an unusual challenge. The spacecraft hurtled straight toward its target with barely any change in lighting or perspective, making it difficult to distinguish real features from possible lighting artifacts. To prove the legitimacy of the streaks, the team mapped them back to their origin in a single region near Dimorphos’ edge—distinctly offset from where the sun was directly overhead. By taking this approach, the team concluded that the marks left by ‘cosmic snowballs’ weren’t just a trick of the lighting after all.
“As we refined our 3D model of the moon the fan-shaped streaks became clearer, not fainter,” Farnham said. “It confirmed to us that we were working with something real.”
Previously, scientists observed indirect evidence that sunlight makes small asteroids spin faster, causing material to fly off their surfaces. But the UMD team’s newly refined models of the asteroid moon Dimorphos provide the first visual confirmation of this phenomenon and identify exactly where shed material from its primary asteroid, Didymos, landed. Further calculations led by UMD alum Harrison Agrusa (M.S. ’19, Ph.D. ’22, astronomy) also showed that the material left Didymos at 30.7 centimeters per second—slower than the average human walking speed.
“That would explain the distinctive fan-shaped marks,” Sunshine said. “Instead of even spreading, these slow-moving impacts would create a deposit rather than a crater. And they are centered on the equator as predicted from modeling material spun off the primary.”
To test their theories, the researchers led by former UMD postdoctoral associate Esteban Wright performed a series of laboratory experiments at UMD’s Institute for Physical Science and Technology. They dropped marbles into sand scattered with painted gravel to simulate boulders on Dimorphos. High-speed cameras captured the experiment, revealing that boulders blocked some material while letting other particles stream between them—creating ray-like patterns matching those on Dimorphos.
Computer simulations of impacts of loose clumps of dust carried out at Lawrence Livermore National Laboratory confirmed the results. Whether the impactor was a compact rock, like the marble, or a looser clump of material, boulders on the asteroid’s surface naturally sculpted the ‘cosmic snowballs’ into fan-like rays on the ground.
“We could see these marks on Dimorphos from that footage captured by the DART spacecraft right before the big collision, proof that there was material exchange between it and Didymos,” Sunshine said. “The fan line deposit should extend to side of the moon we did not hit, and there is a possibility it was not destroyed by the impact.”
The European Space Agency’s Hera mission, set to arrive at Didymos in December 2026, may reveal whether these features survived DART’s collision. Sunshine and her team predict Hera might also observe new ray patterns created by boulders that the DART spacecraft knocked loose, shedding new light on asteroids that could pose a threat to Earth.
“These new details emerging from this research are crucial to our understanding of near-Earth asteroids and how they evolve,” Sunshine said. “We now know that they’re far more dynamic than previously believed, which will help us improve our models and our planetary defense measures.”
NASA knocked an asteroid off course in 2022 in a pioneering test of humanity's ability to defend Earth. Its spacecraft's impact pushed the space rock into a slightly different orbit around the Sun, according to new research published Friday.
Issued on: 07/03/2026 -
By: FRANCE 24
Four years ago, NASA purposely smashed a spacecraft into a small asteroid to see if they could deflect it – a test to prove humanity could protect Earth from threatening space rocks.
The experiment pushed the moonlet asteroid Dimorphos into a smaller, faster route around its sibling Didymos – and according to new research out Friday, it also pushed the pair into a slightly different orbit around the Sun.
The test on Dimorphos was never based on any actual threat to our planet.
But the successful experiment and additional analysis offers a solid data point to mount a defence if any such eventual threat is detected, researchers said.
"This study marks a notable step forward in our ability to prevent future asteroid impacts on Earth," the team of international researchers wrote in their new paper published in the journal Science Advances.
Their observations detailed in the paper showed that the Double Asteroid Redirection Test (DART) in 2022 marked "the first time a human-made object has measurably altered the path of a celestial body around the Sun", NASA said in a statement.
Rahil Makadia, the study's lead author, said his team tracked stellar occultations – the moment when an asteroid passes in front of a star, causing a brief dimming for less than a second – to obtain hyper-precise measurements of the asteroid's position, speed and shape.
Tiny change, significant deflection
Obtaining this data is no small feat. The team relied on volunteer astronomers from around the globe, who recorded 22 of these stellar occultations.
Using that data along with years of additional observations, Makadia said the team was able to measure Didymos's orbit around the sun with precision.
"We were able to measure what this change was exactly," he said, and make computations that could assist with future "planetary defense efforts".
READ MORE How Earth can defend itself against 'city killer' asteroid
The orbital change was miniscule – just 0.15 seconds.
But it's enough to make a difference, scientists say.
"This is a tiny change to the orbit, but given enough time, even a tiny change can grow to a significant deflection," said Thomas Statler, lead scientist for solar system small bodies at NASA Headquarters in Washington, in a statement.
"The team's amazingly precise measurement again validates kinetic impact as a technique for defending Earth against asteroid hazards and shows how a binary asteroid might be deflected by impacting just one member of the pair."
Rice selected to lead US Space Force Strategic Technology Institute 4
Alexander to lead multi-institute team to develop cutting-edge remote sensing technologies
Rice University
Rice University has signed an $8.1 million cooperative agreement to lead the United States Space Force University Consortium/Space Strategic Technology Institute 4 (SSTI), called the Center for Advanced Space Sensing Technologies (CASST) at Rice. Led by David Alexander, director of the Rice Space Institute, CASST will bring new technologies to advance remote sensing and sensemaking from space.
The research team includes Rice professors and staff Kevin Kelly, Tomasz Tkaczyk, Kaden Hazzard, Mark Jernigan and Vinod Veedu, as well as collaborators from University of California, Los Angeles; University of California, Santa Barbara; Georgia Institute of Technology; and Aegis Aerospace in Houston.
“This investment positions Rice at the forefront of the technologies that will define how we see, understand and operate in space,” said Amy Dittmar, the Howard R. Hughes Provost and executive vice president for academic affairs. “By bringing together advanced remote sensing, AI-driven analysis and cross-institutional expertise, CASST will help transform raw space data into real-time insight and expand the frontiers of scientific discovery.”
USSF, established in 2019, is the newest branch of the American armed services, formed in response to increased everyday reliance on space technologies. USSF uses space sensors to provide real-time information about space environments and potential threats in support of its mission to ensure security and superiority in the space domain. In support of that goal, USSF is partnering with research universities to support creation of Space Strategic Technology Institutes — CASST is the fourth such body established under this initiative. Funded by USSF and led by researchers, SSTIs facilitate collaborative applied research and drive transformative breakthroughs and technologies.
“Rice has helped shape the modern era of space research, and CASST marks a bold step into what comes next,” said David Sholl, executive vice president for research. “As space becomes more contested and more essential to daily life, the ability to rapidly sense, interpret and act on what’s happening beyond Earth is critical. This center brings together the materials, engineering and data science innovations needed to deliver that capability.”
CASST will integrate existing leading-edge technologies into space sensors, expand their capabilities then optimize sensors to meet the specific challenges of use in space. The team will also work to miniaturize sensors while developing and implementing low-resource fabrication techniques. The researchers will use artificial intelligence and machine learning to analyze sensor data, allowing for real-time decision-making and decision support in response to sensor data.
“I’m excited to be leading this incredible collaborative effort,” said Alexander, professor of physics and astronomy and principal investigator on the project. “CASST will enable us to expand the range, ability and optimization of space remote sensing, reduce cost and resources required to build them and ensure the data they produce can be used in real-time to support USSF decision-making.”
Alexander is an inaugural member of the Texas Aerospace Research and Space Economy Consortium and serves on the boards of the Houston Spaceport Development Corporation, SpaceCom and the Sasakawa International Center for Space Architecture. He recently served on the board of the American Astronautical Society.
Such collaborations are emblematic of Rice’s rich history in space exploration. In 1959, Rice initiated research collaborations with a newly established NASA. Since then, the university has maintained a leadership role in advancing space science and technology with initiatives such as the Rice Space Institute and partnerships with other leading space organizations.
“CASST is a catalyst for Rice’s expanded role in national security. As a first step in a vital defense partnership, it fuses Rice’s research excellence with the USSF’s vision for a secure and superior space frontier,” said Veedu, assistant vice president for research and head of the university’s Defense Research Advancement initiative.
Into the heart of a dynamical neutron star
Neutron stars harbor some of the most extreme environments in the universe: their densities soar to several times those of atomic nuclei, and they possess some of the strongest gravitational fields of any known objects, surpassed only by black holes. First observed in the 1960s, much of the internal composition of neutron stars is still unknown. Scientists are beginning to look to gravitational waves emitted by binary neutron-star inspirals—pairs of mutually orbiting neutron stars—as possible sources of information about their interiors.
Physicists at the University of Illinois Urbana-Champaign, together with colleagues at the University of California, Santa Barbara, Montana State University, and the Tata Institute of Fundamental Research in India have made a major theoretical breakthrough in understanding how inspiraling binary neutron stars respond to tidal forces, a key step in elucidating neutron stars’ makeup. The team has proven that the time-dependent tidal responses of such stars can be described in terms of their oscillatory behavior, or modes, extending an analogous result from Newtonian gravity to the relativistic setting.
This research was published as an Editors’ Suggestion in the journal Physical Review Letters on February 18, 2026, and paves the way to probing the internal structure of neutron stars and some of nature’s most extreme types of matter using gravitational waves.
Neutron stars: a natural laboratory to study extreme matter
As their name suggests, neutron stars are partly made of neutrons, which can form when protons and electrons are squeezed to pressures so high that they essentially “fuse” together. But neutrons aren’t the whole story. Leading theories suggest that heavy elements, free electrons, and free protons are significant components too. Some even suspect that quantum superfluid and superconducting phases arise deeper down. These conjectures, however, are difficult to verify, and much of the interior composition—especially inside the core—is still a giant question mark.
But neutron stars aren’t just interesting in their own right. Scientists believe they can tell us about extreme physics in general. Theorists surmise that neutron stars represent one instance of a more general kind of matter known as a quark-gluon plasma, a highly dense, hot state of matter composed of quarks, the elementary building blocks of protons and neutrons. Such matter exists in only the most extreme environments, such as the early universe in the first few microseconds following the Big Bang.
The only way to study quark-gluon plasma on Earth is by smashing high-energy particles together in particle colliders, which probe such plasmas at extraordinarily high temperatures. At lower temperatures, though, no lab-based methods exist.
Illinois Physics Professor Nicolás Yunes said, “It’s very hard to study the physics of matter at such high densities and, relatively speaking, low temperatures. But the universe provides a natural lab to study this kind of matter through neutron stars.”
Obviously, because neutron stars can’t be studied on Earth, physicists must infer their properties from astrophysical observations, which have traditionally been limited to electromagnetic observations. With the advent of gravitational-wave astronomy, however, physicists have realized a powerful alternative that may enable them to peer into the very heart of a neutron star.
Whispers in gravitational waves
Sometimes neutron stars form binary systems, where two stars move about a common center of mass. Caught in each other’s orbit, they begin to spiral in toward each other, losing energy to gravitational waves—vibrations in spacetime that propagate outward at the speed of light. As they spiral in, each star tugs on its partner through gravity, producing tidal forces like the Moon does on Earth, before finally merging in a violent collision.
Depiction of a pair of neutron stars during an inspiral. Each star exerts tidal forces on its neighbor, which deforms and excites frequency patterns within, leaving imprints on the gravitational waves emitted. Researchers can analyze these gravitational waves to ‘hear’ what’s going on inside of the stars. Image generated by Abhishek Hegade and Nicolás Yunes using OpenAI ChatGPT Pro.
Former Illinois Physics graduate student and current Princeton University postdoctoral scholar Abhishek Hegade shared, “As they get closer, tidal forces from one star begin to deform the other and vice versa. The amount of deformation depends on what’s inside of the stars.”
These deformations excite oscillatory patterns, called modes, within the stars, just like a hammer excites ringtones when it strikes a bell. These modes leave imprints on the emitted gravitational waves, which can be picked up by sensitive detectors on Earth. By “listening in” to these imprints, scientists may be able to infer what’s going on inside.
Yunes explained, “If we can understand the mode frequencies of oscillation and their decay times, we might be able to determine the composition of neutron stars in a regime not accessible on Earth.”
Getting the tidal response right
To decipher the mode imprints, scientists must first understand how neutron stars respond to tidal forces, a difficult task because the forces—and thus the tidal response—are dynamical, changing rapidly as functions of time, especially during the late stages of inspiral.
For the dynamical tidal responses of non-relativistic Newtonian bodies, the solutions to Newton’s gravitational equations are the modes, which behave like dampened springs, or as physicists put it, damped harmonic oscillators. Moreover, the object’s tidal response can be expressed entirely in terms of these modes—nothing more—forming what’s called a “complete” set.
Yunes stressed that expressing tidal responses in this way is crucial, pointing out, “Without a complete set of modes, it’s entirely possible that you could miss part of the tidal response when you model it, as there could possibly be other pieces you’re omitting from the response’s mathematical description needed to capture all the physics.”
Scientists the world over have hoped that a complete set of modes for binary neutron stars in Einstein’s theory of general relativity exists too. But inspiraling neutron stars are highly relativistic: they’re extremely dense and can approach speeds near 40 percent the speed of light before they merge, strongly distorting spacetime around them. This complex picture and the sheer complexity of the Einstein equations have thwarted physicists’ attempts to determine whether neutron-star modes form a complete set of harmonic oscillators.
First, because there are two stars in a binary system, it's difficult to separate out the effects of one on the other, a situation where the solutions of the stars’ governing equations no longer satisfy the right mathematical constraints, or boundary conditions, required for complete modes to emerge.
“Furthermore,” lead author Hegade added, “a star’s own gravity changes the equations inside and outside of itself. This doesn’t happen in Newtonian gravity, where everything happens in a vacuum. To interpret the star’s tidal response in terms of its modes, you need to know the tidal field both outside and inside of the star too.
“In addition, the loss of energy to gravitational radiation isn’t accounted for by Newtonian theory either. If your system is losing energy, then its modes cannot be complete, so you cannot decompose any perturbation in terms of the modes.”
Finding the modes
To address these hurdles, Yunes’s team broke down the problem into simpler pieces, focusing on one star and viewing its partner as a tidal source. If they could apply the boundary conditions in just the right way, they might be able to find a complete set of modes. Starting with a set of linearized Einstein-Euler equations, which describe how matter generates gravitational fields and evolves in spacetime, they divided the interior and exterior of the star into distinct regions (see diagram): a strong-gravity zone and a weak-gravity zone.
Hegade elaborated, “Physically, it’s a very intuitive way to conceptualize the system. Inside of the star as well as near its surface, gravity is strong. But far away, gravity is weak.
“This process is called a matched-asymptotic expansion, where you zoom in at different scales and then find approximate solutions. Finally, you stitch the solutions together to get something uniform across all scales.”
Decomposing the system in this way and carefully stitching together the strong- and weak-zone solutions enabled the researchers to impose the appropriate boundary conditions piece by piece. Crucially, the incorporation of the weak-gravity zone successfully eliminated radiation in the team’s analysis.
“Our near-zone decomposition ensured that we accounted for the tidal field,” Hegade remarked. “By restricting to the near zone, we took care of radiation by subtracting it out and treating it as a small correction. This allowed us to obtain a complete set of modes.”
The researchers also devised a method for finding the tidal field within the star. By manipulating the Einstein-Euler equations in a suitable way, they discovered they could view the interior tidal field as a driver of oscillations. Specifically, they found that, as long as the tidal field varies without any sudden jumps or sharp corners, the equations spit out harmonic-oscillator modes—just as in Newtonian theory.
From modeling to real data
With the neutron-star’s complete set of harmonic-oscillator modes now in hand, the researchers accomplished exactly what they had set out to do.
Hegade summarized, “We showed two major things. First, we were able to subtract off radiation, finding that a neutron star’s modes do indeed form a complete set. Second, we found that if you consistently solve a certain set of equations using a tidal field that’s sufficiently ‘smooth,’ it’s a solution to the interior of the star, and you can do all the same things in general relativity as in Newtonian gravity.”
The researchers are now eager to see what their new framework might unearth.
Yunes said, “One hope is that we’ll be able to get some information about the neutron-star equation of state at densities found in the inner core of a neutron star. Is there really a quark core, as some have recently claimed? Are there phase transitions occurring inside that we don’t know about yet?”
But answering these questions may have to wait.
Yunes noted, “The signal-to-noise ratios obtained by the LIGO collaboration in their most recent data from 2017 aren’t large enough for us to see the features we’ve captured in our model. In addition, current detectors aren’t that sensitive to sufficiently high frequencies, where most of the information about the neutron-star oscillation modes sit.”
Many are hoping that newer generations of detectors, which are expected to come online in the next few years, together with lucky discoveries of nearby merger events, will ramp up the signal-to-noise ratios and sensitivities required to see more details in the data.
Until then, physicists have lots of time to gear up for the anticipated detectors. Yunes’s team already has some proposed directions: their current framework holds for non-rotating stars only, so they hope to extend it to include rotation as well, as most neutron stars rotate fast. They also plan to repeat their analysis for nonlinear tidal forces and include non-gravitational fields, such as magnetic fields. In terms of their new generalized model, though, they’ve overcome the most challenging obstacle.
Hegade said, “The nice thing about our new framework is that we’ve figured out the hard part—gravity. Now it’s just a matter of applying our models to more realistic configurations.”
This research was funded by the Simons Foundation under Grant No. 896696; by the National Science Foundation under Grant Nos. PHY-2207650, 2012086, 2309360, and 2308415; by NASA under Grant No. 80NSSC22K0806; by the Montana NASA EPSCoR Research Infrastructure Development program under Grant No. 80NSSC22M0042; by the Alfred P. Sloan Foundation under Grant No. FG-2023-20470; and by the Binational Science Foundation under Grant No. 2022136. Any opinions, findings, conclusions or recommendations expressed in this material are those of the researchers and do not necessarily reflect the views of the funding agencies.
Journal
Physical Review Letters
Article Title
Relativistic and Dynamical Love Numbers
NASA robot’s 10-year mission complete as uni marks rare feat
image:
PhD student Elle Miller (left) and Professor Sethu Vijayakumar (right) with the NASA Valkyrie robot
view moreCredit: University of Edinburgh
A robot developed by NASA in preparation for missions to Mars is returning to the USA following a decade at the University of Edinburgh.
The human-sized robot – named Valkyrie after the female spirits of Norse mythology – is the only one of its kind outside of the USA, and one of just three prototypes in the world.
Students and staff have bid a fond farewell to Valkyrie as it returns to NASA’s Johnson Space Centre in Texas, after the end of a 10-year lease with the University.
Researchers will look to continue working closely with NASA on a range of other projects, specifically focusing on improving whole-body manipulation and perception in humanoid robots.
Valkyrie was one of the most advanced humanoid robots in the world when it arrived in Edinburgh in 2016.
NASA aimed to equip Valkyrie to go to Mars many years before astronauts are able to make the journey, for pre-deployment tasks and to maintain assets on the Red Planet.
Standing 1.8 metres tall and weighing some 125 kg, Valkyrie’s human-like shape was designed to enable it to work alongside people or carry out high-risk tasks, sometimes in environments inhospitable to humans. Valkyrie’s unique hardware included so-called Series Elastic Actuators and a range of sensors, components that are crucial for safe, close human-robot interactions.
On delivery, the humanoid could walk on flat ground and perform basic movements, such as holding and manipulating objects. During its time in Edinburgh, researchers worked to give Valkyrie a more sophisticated set of skills using AI in the form of machine learning, enabling it to better understand and respond to its surroundings.
Scientists improved the robot’s handling and walking capabilities, and helped Valkyrie use its on-board sensors to better make sense of its environment, improving its manoeuvrability.
The focus of research involving Valkyrie has been on teaching it to adapt to changing conditions using data, navigate uneven or unpredictable surfaces, and developing smarter ways of connecting what the robot sees to what it does — all fast enough to work in the real world.
Research on Valkyrie was conducted at the Edinburgh Centre for Robotics, a joint initiative between the University of Edinburgh and Heriot-Watt University. Dozens of PhD students and researchers from the Centre carried out research using Valkyrie, enabling important developments in humanoid control, motion planning and perception.
The project was supported by the Engineering and Physical Sciences Research Council, part of UK Research and Innovation (UKRI).
Dr Vladimir Ivan is a former student at the University of Edinburgh who worked on Valkyrie, and is now Chief Technical Officer at a robotics start-up, Touchlab, based in Edinburgh.
Dr Vladimir Ivan said: “Hosting NASA Valkyrie at the University of Edinburgh was a rare privilege at a time when humanoid robots were not commercially available and only a handful of research prototypes existed worldwide. It gave us a unique opportunity to advance fundamental research in mobility and stability – work that has since evolved into humanoid systems we see in today - while helping to train and inspire a generation of outstanding roboticists. Valkyrie’s presence also helped catalyse Edinburgh’s evolution into a vibrant robotics hub, known for world-class research, thought leadership, and a thriving environment to grow knowledge, ideas, and robotics businesses.
Research into humanoid robots will continue at Edinburgh using Talos – a 1.75-metre-tall robot that the University took delivery of in 2020.
Scientists use Talos to study how robots walk, balance and use tools, and how they employ machine learning to adapt to ever-changing environments, using a form of human-robot cooperative working known as dyadic human interaction.
Advances in the research could have applications in a range of areas, including assisted living and healthcare settings.
Professor Sethu Vijayakumar, Personal Chair in Robotics and Director of the Edinburgh Centre for Robotics at the University of Edinburgh, said: “It was a gamble to invest so heavily in humanoids research back in the 2010s, when the scalability of the adaptive learning-based methods for robot planning and control we were advocating was not obvious. In hindsight, this bold decision has contributed to the exciting wave of data-driven humanoid robot research that is now taken for granted. Valkyrie was indeed a trendsetter, benefitting from world-leading hardware from NASA. We will miss her, but it has been a privilege. Thank you for all the fun, Valkyrie!”
The Valkyrie robot being dismantled
A close-up of the Valkyrie robot being dismantled.
Credit
University of Edinburgh
Telescope reveals surprising secrets in Jupiter's northern lights
image:
Katie Knowles of Northumbria University, UK.
view moreCredit: (Credit Northumbria University/Barry Pells)
An international team of scientists, led by a PhD researcher from Northumbria University, has made groundbreaking discoveries about a spectacular feature of Jupiter’s northern lights, revealing a never-before-seen temperature structure and dramatic density changes within the top of the giant planet’s atmosphere.
The research, published today in Geophysical Research Letters, provides the first detailed spectral measurements of the infrared auroral footprints of Io and Europa – brilliant glowing patterns in Jupiter’s aurora caused by its Galilean moons interacting with Jupiter's powerful magnetic field.
The images were captured using the James Webb Space Telescope (JWST), an international partnership between NASA, the European Space Agency, and Canadian Space Agency, which uses infrared radiation to look deep into space.
Speaking about the findings, lead author Katie Knowles, a PhD Researcher in Planetary Physics at Northumbria University, explains: "These emissions have been measured before at ultraviolet and infrared wavelengths, but only how brightly they shine. For the first time, we’ve now been able to describe the physical properties of the auroral footprints – the temperature of the upper atmosphere and the ion density, which has never been reported on before."
Unlike Earth's northern lights, which are primarily driven by the solar wind, Jupiter's aurora includes the impact of its four large Galilean moons – Io, Europa, Ganymede, and Callisto – which create their own ‘mini aurora’ on the planet.
Jupiter's powerful magnetic field rotates approximately once every 10 hours along with the planet itself, carrying charged particles with it. But its moons orbit much more slowly – Io, the innermost moon, takes around 42.5 hours to complete one orbit.
As Katie explains: "The moons constantly interact with the magnetic field and plasma surrounding the planet, and that interaction leads to highly energetic particles travelling down magnetic field lines and then crashing into the planet’s atmosphere, creating the auroral footprints that map to where the moons orbit around Jupiter. Jupiter's aurora is the most powerful and constant of any aurora in the Solar System. What we're seeing with the JWST gives us an unprecedented window into how Jupiter's moons directly affect the top of the planet's atmosphere."
The images captured by JWST were taken during time awarded to Dr Henrik Melin and Professor Tom Stallard (Professor of Planetary Astronomy at Northumbria and Katie’s PhD Supervisor). During a 22-hour window of observation time which took place in September 2023, the research team carried out a scan around the edge of Jupiter, chasing the northern lights as they rotated into view. It was during this observation that they also happened to capture the auroral footprints.
However, the footprints created by Io and Europa, did not have the characteristics expected from Jupiter’s main aurora, which is relatively hot and contains a lot of material. Instead, in one snapshot, they discovered a cold spot within Io's auroral footprint that registered temperatures much lower than expected with extraordinarily high densities (higher than they have ever measured before).
Jupiter’s moon Io is the most volcanically active body in our solar system, with its volcanoes ejecting about 1,000 kilograms of material into space every second, feeding the dense plasma surrounding Jupiter. This material becomes ionized and forms a doughnut-shaped cloud around Jupiter called the Io plasma torus. As Io moves through this environment, it generates powerful electrical currents that create the brightest spots in Jupiter's aurora.
The research team found that these auroral footprints contain trihydrogen cation (H₃⁺) densities three times higher than those found in Jupiter's main aurora, with some regions showing density variations of up to 45 times within the same small area.
"We found extreme variability in both temperature and density within Io's auroral footprint that happened on the timescale of minutes," said Katie. "This tells us that the flow of high-energy electrons crashing into Jupiter's atmosphere is changing incredibly rapidly.
"The cold spot registered temperatures of just 538 Kelvin, or 265°C, compared to 766 Kelvin, or 493°C in the rest of Jupiter’s aurora. The cold spot also contained material three times denser than Jupiter's main aurora.”
The findings could extend far beyond Jupiter and open questions about other planetary systems. Saturn's moon, Enceladus, also creates an auroral footprint on the planet, and scientists wonder whether similar phenomena occur there.
"This work opens up entirely new ways of studying not just Jupiter and its other Galilean moons, but potentially other giant planets and their moon systems," said Katie, who is about to complete her PhD at Northumbria University. "We're seeing Jupiter's atmosphere respond to its moons in real-time, which gives us insights into processes that occur throughout our solar system and perhaps further afar.
“We only saw this phenomenon in one of our five snapshots which leave us with questions. How often does this occur? Does it switch on and off? How does it change with different conditions?"
To answer these questions, Katie was awarded over 32 hours of observation time with NASA's Infrared Telescope Facility (IRTF) in Hawaii across six nights in January 2026. This allowed her to watch as the auroral footprint rotated with the planet. She hopes analysis of this data will allow her to determine whether this extreme variability is common or rare.
Katie has presented her findings to international scientists from across the world at the EPSC-DPS Joint Meeting 2025 in Helsinki (Finland) and was also invited to be a Young Scientist Team Member for an International Space Science Institute team meeting in Bern (Switzerland) to further discuss her work.
FURTHER INFORMATION:
Visit the Northumbria University Research Portal to find out more about Katie Knowles’ work.
The paper Short-Term Variability of Jupiter's Satellite Footprints with JWST was published in Geophysical Research Letters on 3 March 2026.
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- Telescope to provide insight into Solar System lightshows
- Ends –
Photo captions:
1 & 2: Katie Knowles of Northumbria University, UK. (Credit Northumbria University/Barry Pells)
3: The NASA/ESA/CSA James Webb Space Telescope has captured the auroral footprints of Io and Europa, providing spectral measurements for the first time, and revealing extreme changes in the physical properties within Io's auroral footprint that are likely linked to the electrons crashing into the top of Jupiter's atmosphere.
Webb/NIRCam Credit: NASA, ESA, CSA, Jupiter ERS Team; image processing by Judy Schmidt.
Webb/NIRSpec Credit: Katie L. Knowles (Northumbria University).
4. James Webb Space Telescope observations of our solar system's largest planet, Jupiter, showing the infrared brightness of the top of its atmosphere, and revealing the auroral footprints of Io and Europa (highlighted by the white box).
Graphic Credit: Dr Henrik Melin (Northumbria University)
5. James Webb Space Telescope observations of our solar system's largest planet, Jupiter, showing the infrared brightness of the top of its atmosphere.
Graphic Credit: Dr Henrik Melin (Northumbria University)
The NASA/ESA/CSA James Webb Space Telescope has captured the auroral footprints of Io and Europa, providing spectral measurements for the first time, and revealing extreme changes in the physical properties within Io's auroral footprint that are likely linked to the electrons crashing into the top of Jupiter's atmosphere.
Webb/NIRCam Credit: NASA, ESA, CSA, Jupiter ERS Team; image processing by Judy Schmidt.
Webb/NIRSpec Credit: Katie L. Knowles (Northumbria University).
Credit
Webb/NIRCam Credit: NASA, ESA, CSA, Jupiter ERS Team; image processing by Judy Schmidt. Webb/NIRSpec Credit: Katie L. Knowles (Northumbria University)
Journal
Geophysical Research Letters
Method of Research
Imaging analysis
Subject of Research
Not applicable
Article Title
Short-Term Variability of Jupiter's Satellite Footprints as Spotted by JWST
Article Publication Date
3-Mar-2026
