SPACE/COSMOS
Structure in the unstructured: New phenomenon discovered in the solar wind
A new mechanism of plasma turbulence in the solar wind was discovered by an international research group
School of Science, The University of Tokyo
image:
Artist's illustration of NASA's “Parker Solar Probe” mission.
view moreCredit: NASA/Johns Hopkins APL/Steve Gribben
Turbulence is ubiquitous and occurs in our everyday lives on Earth, such as when milk is stirred into coffee, or in the stormy motions of the ocean and the atmosphere. Media in space and astrophysical systems can also develop turbulence, but the physics is different because the medium is in an ionized state (known as the plasma state) and the flow motion is strongly coupled to electromagnetic fields. Furthermore, space plasma is collisionless because the medium is so dilute that the particles do not collide with each other. How does plasma develop into turbulence? How is the fluctuation energy distributed in collisionless turbulence? Turbulence in space plasma remains a mystery in physics.
An international research team from the Technische Universität Braunschweig and University of Tokyo in cooperation with Tohoku University, Kyushu University, Osaka University, and multinational research institutes has now demonstrated, for the first time, a reversal phenomenon of magnetic field rotation in space turbulence. A structure emerges within the unstructured space plasma. The results are published in The Astrophysical Journal Letters.
The team from the Institute of Theoretical Physics at the Technische Universität Braunschweig and University of Tokyo in collaboration with researchers from a total of ten countries, has demonstrated a fundamentally new phenomenon. Using high-precision magnetic field and particle data from NASA’s Parker Solar Probe mission, the team showed directly for the first time that the turbulent magnetic fields exhibit a clear reversal of the magnetic field rotation sense over a certain wavelength, and even that the reversal grows and shifts toward longer wavelengths in the radial direction away from the Sun. The reversal coincides with the transition from large-scale, fluid-like dynamics to small-scale, particle-like dynamics.
The discovery of a small-scale phenomenon has a big impact in science
On larger length scales, space plasma behaves like a fluid, and turbulence develops through excitation of vortices and electromagnetic waves. The fluctuations become random, that is, turbulent. However, the magnetic field rotation is not random. The fields preferentially rotate counterclockwise when seeing radially away from the Sun. The rotation, however, looks different on smaller length scales. The fields rotate clockwise when one looks at the turbulent plasma on smaller length scales. This scale just happens to be at the transition scale from flow-like behavior in the plasma to particle-like behavior.
“We see a clear structure in the spectrum, even though the turbulence represents unstructured motions,” says Dr. Masatomi Iizawa (TU Braunschweig), the first author of the article.
Dr. Yokoi (University. of Tokyo) stresses the importance of this finding, “The results are of great significance for both plasma physics and astrophysics.”
A structure forms when the space plasma becomes turbulent, and the key insight lies in the transition from fluid dynamics to particle dynamics. Plasma turbulence plays an important role in astrophysics, such as in the Earth’s magnetosphere, the solar wind, solar eruption, interplanetary space, and accretion disks. Turbulence in space plasma can influence the shock waves and magnetic clouds in interplanetary space produced by solar eruption and is a very important factor in predicting geomagnetic storms.
Reversal of the field rotation from left-handed rotation (blue) to right-handed rotation (red), plotted on the frequency spectrum (y axis) against distance from the Sun x axis). Analysis based on the data from the Parker Solar Probe. A low frequency corresponds to a long wavelength in the spectrum
Credit
Iizawa et al., Astrophys. J. Lett., 2026.
Journal
The Astrophysical Journal Letters
Method of Research
Data/statistical analysis
Subject of Research
Not applicable
Article Title
Nonlocal Evolution of Magnetic Helicity across the Magnetohydrodynamic–Kinetic Interface
Article Publication Date
13-Oct-2026
Space waves reveal where Earth’s magnetic shield is under pressure
University of Oulu, Finland
image:
In this simulation of the Earth’s magnetic field, the solar wind is coming from the right-hand side of the image and Kelvin–Helmholtz waves are visible at the top. The colour indicates the density of the plasma. Image: Lauri Holappa / University of Oulu
view moreCredit: Image: Lauri Holappa / University of Oulu
A new study led by researchers at the University of Oulu sheds light on a poorly understood part of space weather: where powerful waves form at the edge of Earth’s magnetic shield, and where the solar wind can find a way through.
- A new study explains why wave activity at the edge of Earth’s magnetic shield is stronger in some regions than others. The cause is the uneven draping of the solar wind’s magnetic field around Earth’s own magnetic field.
- The phenomenon can be compared to waves meeting a breakwater: the water does not move in the same way on both sides.
- The results can help improve understanding of where the solar wind affects Earth most strongly and how these effects can be represented in space weather models.
What happens at the edge of Earth’s magnetic shield?
Earth is surrounded by a magnetic field that forms a protective region known as the magnetosphere. It shields the planet from particles and energy streaming from the Sun, a flow called the solar wind. But the shield is not sealed. At its outer edge, the solar wind constantly interacts with Earth’s magnetic environment.
These interactions help drive space weather. On Earth, their effects can appear as auroras, but strong solar storms can also disturb satellites, positioning systems, radio communications and power grids. The new study focuses on the wave motion that forms where the fast-moving solar wind brushes past the edge of the magnetosphere.
The waves are known as Kelvin–Helmholtz waves. Similar wave patterns can sometimes be seen in clouds, and related phenomena occur in the Sun’s atmosphere, at the edges of other planets’ magnetic fields and in interstellar space.
“This finding grew out of a long process of thinking through what I was seeing. In 2020, when I was visiting NASA as a postdoctoral researcher, I noticed unusual simulation images of the magnetosphere. I later realised that they showed Kelvin–Helmholtz waves at the edge of the magnetosphere, and that the different behaviour of the waves on different sides was part of the same phenomenon,” says Academy Research Fellow Lauri Holappa from the University of Oulu. The waves do not form as neat mirror images. Instead, they appear asymmetrically on different sides of the magnetosphere.
Studying these boundary waves is challenging because satellites pass through the most active regions only rarely. This has left researchers with limited information about how the waves behave under different solar wind conditions. In the new study, the researchers examined their formation using computer models of the entire magnetosphere.
“Asymmetries in the wave motion at the edge of the magnetic field have been observed before, but now we were able to show how they arise,” Holappa says.
The results show that the asymmetric wave activity is caused by the way the solar wind’s magnetic field meets Earth’s magnetic field. It does not flow around Earth evenly. Instead, it wraps and drapes around the magnetosphere in an asymmetric manner. This draped magnetic field can dampen the waves, but the damping effect is not the same everywhere.
The strongest wave activity was found to form in the winter hemisphere, which is facing away from the Sun. Depending on the direction of the solar wind’s magnetic field, it is concentrated either on the dawn side or the dusk side.
The study IMF By-Controlled Dawn–Dusk and Hemispheric Asymmetries of Kelvin–Helmholtz Waves and Reconnection Geometry Under Negative Dipole Tilt was published in September 2026 in the scientific journal Geophysical Research Letters.
Further information:
Academy Research Fellow Lauri Holappa: +358 50 350 2856, lauri.holappa@oulu.fi
Space Physics and Astronomy research at the University of Oulu
Space weather researcher sees more than beauty in aurora borealis
Kelvin–Helmholtz waves can also be seen in clouds. See for example image: Famartin, CC BY-SA 4.0 via Wikimedia Commons
Journal
Geophysical Research Letters
Article Title
IMF By-Controlled Dawn–Dusk and Hemispheric Asymmetries of Kelvin–Helmholtz Waves and Reconnection Geometry Under Negative Dipole Tilt
Kelvin–Helmholtz waves can also be seen in a river’s current. A counter-current meets the main current, causing eddies and Kelvin–Helmholtz waves. A similar encounter between opposing currents occurs at the edge of the magnetosphere. Image: Katariina Nykyri
Credit
Image: Katariina Nykyri
Trailblazing technique uncovers real shape of scorching-hot exoplanet atmospheres
University of Bristol
image:
The shape of WASP-17b’s atmosphere mapped using transmission strings. The planet has a broad banded jet around the equator with vast wind speeds which transport material and heat from the permanently irradiated dayside to the permanently shadowed nightside. The atmosphere over the equator of the evening limb (left) is hot as it is transported from the dayside of the planet, while the atmosphere on the right has cooled as it traversed the nightside and passes back to the dayside via the morning limb. Using transmission strings Dr Alderson and her team measured the shape of this transmitting limb as a function of angle across the poles of the planet for the first time.
view moreCredit: Engine House and Hannah Wakeford
Until now the alien white-hot worlds of exoplanets have been depicted as circular, but new research has revealed the true shape of their atmospheres to be a deformed sphere rather than perfectly circular.
The study, co-led by Cornell University in the US and the University of Bristol in the UK, presents the first application of a pioneering method called ‘transmission strings’, developed at Bristol by astrophysicists Dr David Grant and Dr Hannah Wakeford, which unravels for the first time an exoplanet’s uneven contours using insights from the largest telescope in Space, JWST.
Its results, published in the journal Nature Astronomy, show the atmosphere is circular, but also asymmetrical with one more extended side. Such dimensions expose how intense heat and whipping winds influence the atmosphere of the ‘hot Jupiter’ WASP-17b exoplanet, orbiting a star some 1,300 light-years from planet Earth.
Lead author Dr Lili Alderson, a Klarman Postdoctoral Fellow at Cornell University, embarked on the extraplanetary investigation at the University of Bristol, where she gained her doctoral degree in Physics.
Dr Alderson said: “This is proof of concept that planets are in fact 3D objects, and that consistently, as they go around their star, what we predict should be happening is happening. To move beyond computational exercises and see it for real is a different matter.”
The findings about WASP-17b’s atmospheric chemical composition and temperature shifts – from equator to poles, and between permanent day and night sides – are consistent with theoretical predictions and other modelling techniques. Together they create one of the most comprehensive, 3D views of an exoplanet’s atmosphere and provide an important benchmark for comparison with the more than 6,000 other exoplanets confirmed to date.
Co-author Dr Hannah Wakeford, Associate Professor in Astrophysics at the University of Bristol, said: “Planets are temperamental, their atmospheres complex and chaotic. The fact that all of these numbers came together and showed us this very structured, dynamical picture of this giant world over 1,000 light-years away was just really exciting.”
Previous research has used JWST’s game-changing sensitivity to pioneer a technique called eclipse mapping, which measures changes in light as an exoplanet swings behind its host star. The new ‘transmission strings’ method, also called transit mapping, tracks the planet as it crosses in front of the star, capturing the composition of light around the edge of the planet’s atmosphere, or limb, from different angles. By contrast, traditional modelling extracts a spectrum only as an average across the entire limb.
“Rather than assuming your atmosphere is a circle with the same radius all the way around, our technique allows you to pull out different distances from the centre to the edge of the planet,” Dr Alderson said. “We’re able to go around the edge. So, we’ve gone from a ring to understanding where on the ring the gemstones are, so to speak.”
The researchers revealed a “gem” where theory and previous modelling indicated one should be on WASP-17b, on the “evening” side of its equator. There, jets of wind transport heat from the planet’s permanently illuminated day side around towards the permanently shadowed night side, inflating the atmosphere relative to the equator’s cooler “morning” side. Transit mapping verified other characteristics of WASP-17b.
Dr Alderson added: “Theory predicts that the morning and the evening sides should have a strong temperature difference, and WASP-17b fits really nicely in that trend – pretty much bang-on what we thought it would be.”
This successful demonstration of transmission strings on WASP-17b paves the way for mapping many more candidates. The process is starting to differentiate conditions across exoplanet latitudes, beyond just day and night sides, and providing a first step towards mapping weather-scale patterns in exoplanet climates.
Dr Wakeford said: “Having this very robust mathematical model that we can apply to this state-of-the-art data is incredibly exciting. The results are a really beautiful demonstration of the dynamics that are going on in these multidimensional and multifaceted worlds.”
The research analysed data collected by the JWST Telescope Scientist Deep Reconnaissance of Exoplanet Atmospheres through Multi-instrument Spectroscopy (TST DREAMS) Guaranteed Time Observations programme. It was funded by NASA, the UK Research and Innovation (UKRI) Science and Technology Facilities Council (STFC), and the Klarman Fellowship.
WASP-17b transiting in front of its star revealing the shape of its absorbing atmosphere through JWST observations. The hot extended red side is gas transported from the permanently irradiated dayside across the evening limb of the planet, the cooler blue side is less extended as the gas has cooled across the nightside of the planet and it is being transported across the morning limb. This technique can be used to measure the changing weather patters around the planet resolving the shape of the planet as a function of angle around the transmitting limb.
Credit
Engine House and Hannah Wakeford
Journal
Nature Astronomy
Subject of Research
Not applicable
Article Title
‘A Spatial Map of the Atmospheric Limb of a Hot Jupiter’
Article Publication Date
14-Oct-2026
Pulling strings: New method maps exoplanet’s true shape
Media note: Two artist impressions can be found and downloaded here.
ITHACA, N.Y. - Mathematical models have necessarily reduced distant exoplanets to idealized circles – until now.
Leveraging observations by NASA’s James Webb Space Telescope (JWST) and a new mapping method called “transmission strings,” a Cornell-led international research team has for the first time resolved an exoplanet’s uneven contours. The resulting shape – circle-like, of course, but slightly egg-shaped, with one more extended side – details how intense heat and whipping winds influence the atmosphere of the “hot Jupiter” WASP-17b, orbiting a star more than 1,000 light years from Earth.
The team says its findings about the planet’s chemical composition and temperature shifts – from equator to poles, and between permanent day and night sides – are consistent with theoretical predictions and other modeling techniques. Together, they create one of the most comprehensive, three-dimensional views of an exoplanet’s atmosphere among the more than 6,000 exoplanets confirmed to date, making WASP-17b a benchmark for comparisons with others.
“This is proof of concept that planets are in fact 3D objects, and that consistently, as they go around their star, what we predict should be happening is happening,” said Lili Alderson, a Klarman Postdoctoral Fellow in the College of Arts and Sciences. “To move beyond computational exercises and see it for real is a different matter.”
Alderson is the first author of “A Spatial Map of the Atmospheric Limb of a Hot Jupiter,” published Oct. 14 in Nature Astronomy. Twenty co-authors include Nikole Lewis, associate professor in the Department of Astronomy (A&S) and Alderson’s fellowship adviser, and doctoral students Maura Lally and Elijah Mullens; and from the University of Bristol, U.K., where Alderson earned her doctoral degree and began the work, second author Hannah Wakeford, associate professor of astrophysics, and Senior Postdoctoral Associate David Grant and doctoral student Daniel Valentine.
“Planets are temperamental, their atmospheres complex and chaotic,” Wakeford said. “The fact that all of these numbers came together and showed us this very structured, dynamical picture of this giant world over 1,000 light years away was just really exciting.”
Cornell-led research previously has used JWST’s game-changing sensitivity to pioneer a technique called eclipse mapping, which measures changes in light as an exoplanet swings behind its host star. The new transmission strings method – also called transit mapping – tracks the planet as it crosses in front of the star, capturing the composition of light around the edge of the planet’s atmosphere, or limb, from different angles. Traditional modeling, in contrast, extracts a spectrum only as an average across the entire limb.
“Rather than assuming your planet is a circle with the same radius all the way around, our technique allows you to pull out different distances from the center to the edge of the planet,” Alderson said. “We’re able to go around the edge. So, we’ve gone from a ring to understanding where on the ring the gemstones are, so to speak.”
The team revealed a “gem” where theory and prior modeling suggested one should be on WASP-17b, on the “evening” side of its equator. There, jets of wind transport heat from the planet’s permanently illuminated day side around toward the permanently shadowed night side, inflating the atmosphere relative to the equator’s cooler “morning” side. Transit mapping verified other characteristics of WASP-17b.
“Theory predicts that the morning and the evening sides should have a strong temperature difference, and WASP 17b fits really nicely in that trend – pretty much bang-on what we thought it would be,” Alderson said. “It was also nice to confirm that important molecules like water and carbon dioxide are pretty consistent all the way around the limb.”
Alderson and Wakeford said the successful demonstration of transmission strings on WASP-17b paves the way for mapping many more candidates. The process is beginning to differentiate conditions across exoplanet latitudes – not just between day and night sides – and a first step toward mapping weather-scale patterns in exoplanet climates.
“Having this very robust mathematical model that we can apply to this state-of-the-art data is incredibly exciting,” Wakeford said. “The results are a really beautiful demonstration of the dynamics that are going on in these multidimensional and multifaceted worlds.”
In addition to her ongoing collaboration with Wakeford, Alderson said her work with Lewis, as well as the time and computational resources afforded by the Klarman Fellowship, had accelerated this first-of-its-kind transit mapping.
“The first-ever use of this new technique shows us that our understanding of these planets is correct, that our different methods all agree with each other,” she said. “And that the future is very bright for being able to use these techniques to get deep dives on many different planets in the coming years.”
The research analyzed data collected by the JWST Telescope Scientist Team Deep Reconnaissance of Exoplanet Atmospheres through Multi-instrument Spectroscopy (TST DREAMS) Guaranteed Time Observations program, for which Lewis served as principal investigator. Funding support came from NASA, the U.K. Research and Innovation Science and Technology Facilities Council, and the Klarman Fellowship.
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