Scientists have developed a new technique to map the winds on the ultra-hot Jupiter WASP-76b at different altitudes. By studying how iron absorbs light, they’ve created the first-ever vertical weather profile of this extreme world, revealing how its atmosphere works from the inside out.

We already knew WASP-76b was wild. It’s a world so hot that iron vaporizes on its day side and then rains down as molten metal on its night side. But researchers wanted to look deeper. How do the planet’s ferocious winds, which carry this iron vapor, behave at different altitudes? A team led by Aurora Kesseli and Hayley Beltz pioneered a new method using data from the ESPRESSO spectrograph. They sorted the light-absorbing signatures of iron (Fe I) based on their strength, or opacity. Very opaque lines can only be seen from the very top of the atmosphere, while less opaque lines allow us to peer deeper down. By analyzing these different sets of lines, they could measure the wind speed at different layers for the first time, effectively creating a vertical slice of an alien planet’s weather.

Read the original research paper on arXiv: ‘Up, Up, and Away: Winds and Dynamical Structure as a Function of Altitude in the Ultra-Hot Jupiter WASP-76b’

We’re moving from a 2D picture to a 3D understanding of these incredible atmospheres.
— Aurora Y. Kesseli, Lead Author

Imagine you’re trying to see the ground from a plane on a foggy day. A very thick, dense fog bank (a strong opacity line) would only let you see the very top layer. But if the fog were a much thinner mist (weak opacity), you might be able to see all the way down to the ground. Astronomers used this exact principle with iron atoms in WASP-76b’s atmosphere. Iron absorbs light at many specific wavelengths. Some of these absorption lines are naturally ‘stronger’ than others. The strong lines get blocked high up in the atmosphere, giving us information about the winds there. The weaker lines aren’t fully absorbed until the starlight has traveled much deeper, revealing the wind patterns in the lower layers. By separating and analyzing these, scientists could compare the ‘high-altitude winds’ to the ‘low-altitude winds’ and build a vertical profile.

A key question on a world like WASP-76b is what controls its atmosphere. The researchers tested three different climate models, but the most interesting part was the role of magnetic fields. On Earth, our magnetic field channels the solar wind to create beautiful auroras. On a hot Jupiter, a magnetic field can act like a giant brake, creating friction—or ‘magnetic drag’—on the hot, ionized gases whipping around the planet. The study found that a model including a realistic magnetic field (the ‘3G’ model) did a better job of explaining the observed wind patterns than a simple model with no magnetism or one with a crude, uniform drag. This is strong evidence that, just like on Earth, magnetic fields are a dominant force in shaping a planet’s climate and space weather, even one 640 light-years away.

The data seems to favor a model with magnetic effects, suggesting these invisible forces are shaping the entire planet.
— Hayley Beltz, Lead Author

The goal was to see which computer simulation of WASP-76b best matched reality. After using the binary mask technique to isolate the weak and strong iron lines from the ESPRESSO data, the team measured key properties like the wind speed (velocity shift) and the wind’s turbulence (line width) for each atmospheric layer. They then compared these real-world measurements to the predictions from three Global Circulation Models (GCMs): one with no drag, one with uniform drag, and one with a sophisticated magnetic drag. The uniform drag model failed, predicting trends opposite to what was seen. The battle was between the no-drag (hydrodynamic) and magnetic models. While neither was perfect, the magnetic model better matched subtle trends in the data, especially how the signal changed from the start to the end of the transit. This work provides a powerful new way to test and refine our theories about how exoplanet atmospheres work.

Q: So, are the winds different at different heights on WASP-76b?
A: Yes, that’s what the data suggests. The research found tentative trends that winds are more blueshifted (moving towards us faster) and the flow is less turbulent deeper in the atmosphere. Higher up, the wind patterns appear wider and more complex.

Q: What is ‘magnetic drag’?
A: It’s a force that occurs when a magnetic field interacts with a moving, electrically conductive fluid, like the hot ionized gas in WASP-76b’s atmosphere. It acts like a form of friction, slowing down and redirecting the atmospheric winds.

Q: Why can’t the models perfectly match the wind speeds?
A: Exoplanet atmospheres are incredibly complex. There’s likely ‘missing physics’ in the models, such as the effects of hydrogen atoms splitting apart at high temperatures, or perhaps the magnetic field is even stronger or more complex than assumed. This study helps pinpoint where those models need to improve.

Q: Can this technique be used on other planets?
A: Yes, absolutely! This method can be applied to any exoplanet with a clear atmosphere and strong absorption lines observed with a high-resolution spectrograph. As telescopes like the Extremely Large Telescope (ELT) come online, we’ll be able to do this for more planets with even higher precision.

Decades after a comet crashed into Jupiter, scientists discovered its powerful auroras are actively scrubbing a specific chemical from the atmosphere, revealing that these beautiful light shows are also massive chemical factories.

Back in 1994, the world watched as fragments of Comet Shoemaker-Levy 9 spectacularly crashed into Jupiter. This cosmic collision was more than just a fireworks display; it delivered a cocktail of new chemicals, including carbon monoxide (CO) and hydrogen cyanide (HCN), into the gas giant’s stratosphere. Scientists have been tracking these chemicals ever since, using them as tracers to understand Jupiter’s winds and chemistry. Fast forward to 2017. Using the powerful ALMA telescope, researchers mapped these two molecules with stunning detail. The results were puzzling. The CO had spread out evenly across the entire planet, just as expected. But the HCN was a different story. In the regions around Jupiter’s north and south poles, where the brilliant auroras dance, the HCN had almost completely vanished. It was a cosmic mystery: two chemicals delivered together were now behaving in completely different ways.

Read the original research paper: ‘Evidence for auroral influence on Jupiter’s nitrogen and oxygen chemistry revealed by ALMA’

Seeing CO spread so uniformly confirmed our models, but the massive depletion of HCN in the auroral regions was a total surprise.
— T. Cavalié, Lead Researcher

Imagine dropping two different colored dyes into a swimming pool. You’d expect them both to spread out and mix evenly over time. That’s what scientists thought would happen with CO and HCN in Jupiter’s stratosphere. Both were deposited at similar altitudes by the same comet impact. The fact that CO is now found everywhere from the equator to the poles tells us that Jupiter’s high-altitude winds are very effective at mixing things up. This makes the disappearance of HCN even weirder. If the winds are mixing everything, why is there a giant hole in the HCN distribution right over the poles? A simple ‘dynamical barrier’ or wind pattern can’t be the answer, because it would block CO as well. The solution had to be chemical, and it had to be something happening only at the poles.

The prime suspect? Jupiter’s incredibly powerful auroras. Just like on Earth, auroras are created when energetic particles from a planet’s magnetosphere slam into atmospheric gases. But on Jupiter, this process is supercharged. The paper proposes that this intense energy drives the formation of complex organic molecules, which then clump together to form aerosols — essentially a fine, high-altitude haze or smog. This is where the story takes a turn. The researchers believe that HCN molecules are ‘sticky’ and readily bond to the surface of these auroral aerosol particles. In contrast, the more stable CO molecules do not. Once HCN is locked onto these heavier aerosol particles, they slowly sink deeper into the atmosphere, effectively removing, or ‘scrubbing’, the HCN from the upper layers where ALMA can observe it. The aurora isn’t just a light show; it’s an active chemical trap!

We propose that heterogeneous chemistry bonds HCN on large aurora-produced aerosols… causing the observed depletion.
— The Research Team

This discovery was made possible by the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile. ALMA isn’t one telescope, but an array of 66 high-precision radio antennas working together. This allows it to act like a single, giant telescope, achieving incredible resolution. By tuning to the specific frequencies (or colors) of light emitted by CO and HCN molecules, ALMA can create detailed maps of their location and abundance. The key was its ability to resolve Jupiter’s disk and isolate the polar regions from the rest of the planet. The team analyzed the lineshape of the signal, which reveals the vertical distribution of the gas—telling them not just *if* the chemical was present, but at what altitude. By combining this with temperature data from the Gemini telescope, they could confidently confirm that the HCN wasn’t just hiding; it was truly gone from the upper stratosphere in the auroral zones.

Q: What is hydrogen cyanide?
A: Hydrogen cyanide (HCN) is a simple molecule made of hydrogen, carbon, and nitrogen. While it’s toxic on Earth, it’s a common building block for more complex organic molecules found throughout space, especially in comets.

Q: Why doesn’t carbon monoxide (CO) get trapped too?
A: Carbon monoxide is a very stable and less reactive molecule. The leading theory is that its chemical properties don’t allow it to easily bond to the surface of the organic aerosol particles in the way that HCN can. It simply bounces off while the HCN gets stuck.

Q: Are Jupiter’s auroras like the ones on Earth?
A: They are created by a similar process—charged particles hitting the atmosphere—but Jupiter’s are on a completely different scale. They are thousands of times more energetic and are mainly driven by Jupiter’s immense magnetic field and particles from its volcanic moon, Io. Earth’s auroras are primarily driven by the solar wind.

Q: So the auroras are both destroying and creating HCN?
A: It’s a fascinating paradox! The research suggests that in the upper layers, auroral aerosols are removing HCN. However, deep inside the main auroral oval, there’s evidence that the same energetic particles are creating *new* HCN from nitrogen gas welling up from below. It’s a complex cycle of creation and destruction happening in the same region.

Scientists have designed an exciting new mission called AuroraMag, which uses two identical satellites to simultaneously study the Northern and Southern Lights. Their goal is to finally solve the long-standing mystery of why these incredible light shows are often not perfect mirror images of each other.

We often picture the auroras as perfect mirror images, with the Northern Lights (Aurora Borealis) perfectly matching the Southern Lights (Aurora Australis). But for decades, scientists have known this isn’t always true. Sometimes one is brighter, larger, or shifted to a different position. This phenomenon, called hemispheric asymmetry, is a major puzzle in space physics. Why does Earth’s magnetic shield respond unevenly to the solar wind? To solve this, scientists led by Ankush Bhaskar proposed AuroraMag. This mission concept uses two identical spacecraft, one orbiting over the North Pole and the other over the South Pole. By observing both auroras at the same time with the same instruments, AuroraMag would provide the side-by-side comparison needed to finally understand the forces that create these beautiful, lopsided light shows.

Read the original research paper on arXiv: ‘AuroraMag: Twin Explorer of Asymmetry in Aurora’

This would be the first dedicated twin spacecraft mission to simultaneously study hemispheric asymmetries.
— Ankush Bhaskar, Space Physics Laboratory, ISRO

Several factors can throw off the symmetry of the auroras. First, Earth’s magnetic axis is tilted, so the poles aren’t perfectly aligned with its rotation. This, combined with the seasons, means one pole is often tilted more towards the Sun, changing how it interacts with the solar wind. The biggest factor, however, is the Interplanetary Magnetic Field (IMF) – the Sun’s magnetic field that flows through space with the solar wind. The IMF can have a sideways component (called ‘By’) that effectively ‘twists’ Earth’s magnetosphere. This twist pulls the magnetic connection points in the northern and southern hemispheres in different directions, causing the auroras to form in non-mirrored patterns. AuroraMag would be able to directly measure how this twisting effect channels energy and particles differently into each hemisphere, turning theory into hard data.

Understanding this asymmetry is crucial for deciphering the intricacies of magnetospheric interactions.
— Jayadev Pradeep, Mission Concept Co-Author

Auroras are more than just pretty lights; they are a visual sign of space weather in action. They show us where energy and particles from the Sun are slamming into our upper atmosphere. For satellite operators and power grid managers, understanding this energy input is vital. A major geomagnetic storm can damage technology, but our current view is often incomplete, like trying to understand a storm by looking out of only one window. AuroraMag would give us a total, global picture. By measuring the energy dumping into *both* hemispheres at once, scientists can calculate the full energy budget of a storm. This data would dramatically improve our space weather models, leading to better predictions that can help protect our vital infrastructure. It’s about understanding the aurora not just as a regional phenomenon, but as a key piece of a planet-wide electrical system.

The AuroraMag mission design is incredibly clever. It uses two small, cost-effective satellites, AuroraMag-N and AuroraMag-S. They would be placed in identical but opposite elliptical orbits, flying from a low altitude of 400 km up to a high point of 10,000 km. This ‘rollercoaster’ orbit is key. When far from Earth (at apogee), the X-ray Imager has a wide-angle view to capture the entire auroral oval in one shot. When the satellite swoops in close (at perigee), its other instruments can perform *in-situ* measurements—like taking the temperature of the plasma with the Electron Temperature Analyser, counting particles with the MERiT sensor, and measuring powerful electric currents with its magnetometer. By having two spacecraft perform this dance simultaneously over opposite poles, AuroraMag would provide an unprecedented 3D view of how our planet responds to the Sun.

Q: Why do we need two satellites? Can’t one just fly back and forth?
A: Space weather changes in minutes. For a true comparison, you need to see both the north and south poles at the exact same time. Using two identical satellites is the only way to get a true ‘apples-to-apples’ snapshot of how the auroras are behaving simultaneously.

Q: Why study the aurora in X-rays instead of visible light?
A: Visible light auroras are created by lower-energy electrons. X-ray auroras are produced by the most powerful, high-energy electrons bombarding the atmosphere. Studying the X-rays gives scientists a much clearer picture of where the most intense energy is being deposited during a space weather event.

Q: Is the AuroraMag mission actually being built?
A: Currently, AuroraMag is a ‘mission concept’. This research paper is a detailed proposal presented to the scientific community and space agencies to show why the mission is important and how it could be done. The next step would be for a space agency like ISRO, NASA, or ESA to fund and develop it.

Q: How does knowing about auroral asymmetry help me?
A: This knowledge is key to improving space weather forecasting. Better forecasts help protect the satellites that provide GPS and communications, ensure the stability of our power grids, and keep astronauts safe. It’s fundamental research that strengthens the technology we rely on every day.

Scientists using the Hubble Space Telescope created the first complete map of the aurora on Ganymede, Jupiter’s largest moon. They discovered its auroral lights aren’t complete ovals like Earth’s, but are split into two glowing crescents, a pattern unique in our solar system.

For years, scientists knew Ganymede had an aurora, a faint glow powered by its unique magnetic field. But seeing the whole picture was impossible. Using a massive dataset of 46 observations from the Hubble Space Telescope spanning from 1998 to 2017, a team of researchers painstakingly stitched together the first-ever global brightness map of Ganymede’s ultraviolet aurora. The result was a huge surprise. Instead of a continuous oval of light at each pole, like the ones we see on Earth or even Jupiter, Ganymede’s aurora is distinctly broken. The map revealed two intensely bright auroral crescents on opposite sides of the moon, while the regions in between were dramatically dimmer. This structure had never been seen anywhere else and points to the strange and complex physics happening around Jupiter’s giant moon.

Read the original research paper on arXiv

Our map reveals Ganymede’s auroral ovals are structured in upstream and downstream ‘crescents’.
— Joachim Saur, Corresponding Author

Imagine Ganymede as a large rock in a fast-moving river. The ‘river’ is the plasma—a gas of charged particles—that fills Jupiter’s enormous magnetosphere and flows past Ganymede at incredible speed. The brightest parts of the aurora, the crescents, appear on the upstream side (where the plasma hits the moon head-on) and the downstream side (in its wake). This is where the interaction is most intense, accelerating particles into Ganymede’s thin oxygen atmosphere and making it glow. The sides of the ‘rock’ parallel to the flow—the flanks facing toward and away from Jupiter—experience a much weaker interaction. This causes the aurora to be 3 to 4 times fainter in these regions, creating the ‘broken’ or crescent shape. It’s a visual map of how Ganymede battles the constant stream of plasma from its parent planet.

Auroras are the ultimate sign that a planet or moon has a magnetic field. Ganymede is the only moon in our solar system with one, creating what scientists call a mini-magnetosphere. This map of its broken aurora is a stunning visualization of that mini-magnetosphere in action. Unlike Earth’s global magnetic field which stands strong against the solar wind, Ganymede’s field is tiny and completely embedded within Jupiter’s colossal magnetosphere. The crescent shape shows us exactly where Ganymede’s magnetic field lines connect with Jupiter’s, creating channels for energetic particles to slam into its atmosphere. Studying this unique, ‘sub-Alfvénic’ interaction helps scientists understand the physics of magnetism on a smaller scale and provides clues about how moons can protect a fragile atmosphere even in the harshest environments.

This map will be useful to understand the processes that generate the aurora in Ganymede’s non-rotationally driven, sub-Alfvénic magnetosphere.
— The Research Team

Creating this map was a cosmic puzzle. The researchers used the Space Telescope Imaging Spectrograph (STIS) on Hubble, which observes in ultraviolet light invisible to the human eye. Each of the 46 exposures only captured one hemisphere of Ganymede at a time. The science team had to precisely determine Ganymede’s position and orientation for each image, carefully subtract the glare of reflected sunlight from its icy surface, and correct for the viewing angle. They then projected each clean image onto a flat, global map, similar to how a map of Earth is made from satellite photos. By averaging all 46 maps together, weighted by their exposure time, they built up a complete, high-quality picture of the entire auroral system. This meticulous process turned nearly two decades of snapshots into the first definitive atlas of Ganymede’s alien auroras.

Q: What color are Ganymede’s auroras?
A: Ganymede’s auroras glow primarily in ultraviolet (UV) light, which our eyes cannot see. The color comes from oxygen atoms in its thin atmosphere being excited by charged particles. If we could see in UV, they would likely appear as a purple or faint whitish glow.

Q: Why is Ganymede the only moon with a magnetic field?
A: Scientists believe Ganymede has a molten iron core, similar to Earth’s. The churning motion within this liquid metallic core generates a magnetic field. Other moons are either too small to have retained enough internal heat, or their core composition is different.

Q: Why is it important to map Ganymede’s aurora?
A: The aurora acts like a giant TV screen, showing us what’s happening in Ganymede’s invisible magnetic field and how it interacts with Jupiter. Mapping its brightness and shape helps scientists test their models of plasma physics and understand how this unique ‘mini-magnetosphere’ works.

Q: Will we get a closer look at these auroras?
A: Yes! The European Space Agency’s JUICE (JUpiter ICy moons Explorer) mission is on its way to the Jupiter system and will eventually orbit Ganymede. It carries instruments designed to study Ganymede’s magnetic field and aurora in unprecedented detail, giving us an up-close view of these amazing crescent lights.

Scientists scoured the atmospheres of 12 massive exoplanets for signs of iron hydride, a molecule that acts like a cosmic thermometer. While they didn’t find a conclusive signal, they found tantalizing hints on two super-hot worlds, pushing the limits of how we study alien weather.

In a comprehensive search of archived data, a team of astronomers led by Aurora Y. Kesseli went looking for a specific molecule, iron hydride (FeH), in the skies of 12 different hot Jupiters. Their goal was to use this molecule as a sensitive probe of atmospheric conditions. After carefully analyzing the light filtering through each planet’s atmosphere during a transit, they found no definitive detections. However, two planets stood out: WASP-33b and MASCARA-2b. Both showed faint, low-confidence signals right where the signature of FeH was expected to be. What makes this so intriguing is that these two planets have temperatures between 1800-3000°C, the exact ‘Goldilocks zone’ where scientific models predict FeH should be most abundant. While the signals are too weak to be a confirmed discovery, they provide a tantalizing hint that we are looking in the right place.

Read the original research paper on arXiv: ‘A Search for FeH in Hot-Jupiter Atmospheres…’

We found intriguing hints in the exact places we expected to, but the signals are just too faint to be certain yet.
— Aurora Y. Kesseli, Lead Author (paraphrased)

Why hunt for iron hydride (FeH)? Because it’s a fantastic atmospheric probe. Unlike molecules like water or carbon monoxide, which can exist across a huge range of temperatures, FeH is picky. It only forms in a narrow window of conditions. If an atmosphere is too hot (over 3000°C), the intense heat breaks the bond between the iron and hydrogen atoms. If it’s too cool (below 1500°C), the iron condenses out of the gas phase, forming clouds of solid particles, similar to how water vapor forms ice clouds on Earth. Therefore, finding a strong signal of FeH tells you the temperature of that atmospheric layer with remarkable precision. It acts like a chemical thermometer, giving scientists a clear reading on the conditions in these distant, extreme environments. Its presence, or absence, provides crucial clues for understanding the chemistry and physics of alien skies.

Metal hydrides exist in much more specific regimes… and so can be used as probes of atmospheric conditions.
— Kesseli et al., 2020

At NorthernLightsIceland.com, we know auroras are born from the interaction between the solar wind and a planet’s magnetic field. That magnetic field is generated deep within a planet’s core, which on rocky worlds is made mostly of iron. While hot Jupiters are gas giants, the amount of heavy elements like iron in their composition is a key clue to their formation and internal structure. By searching for iron-bearing molecules like FeH in their atmospheres, scientists can estimate the planet’s overall metal content. A planet rich in heavy elements is more likely to have a dense, differentiated core capable of generating a powerful magnetic field. This invisible shield is crucial for protecting an atmosphere from being stripped away by fierce stellar winds from its nearby star. So, while atmospheric FeH doesn’t directly cause auroras, its detection is a step toward understanding the ingredients needed for a planet to build its own protective magnetic shield.

The team used a technique called high-dispersion transmission spectroscopy. As a planet passes in front of its star, they use an instrument called CARMENES to capture the starlight that filters through the planet’s thin atmospheric layer. Molecules in this atmosphere absorb specific colors of light, leaving tiny dark lines in the star’s spectrum. The challenge is that this planetary signal is incredibly faint and buried in noise from the star itself and from molecules in Earth’s own atmosphere (telluric contamination). To find the signal, they use cross-correlation, comparing their noisy data to a clean, theoretical model of an FeH spectrum. This boosts any matching patterns. They also used an algorithm called SYSREM to systematically identify and remove the noise. This painstaking process of cleaning and amplifying the data allowed them to find the faint hints around WASP-33b and MASCARA-2b.

Q: What is Iron Hydride (FeH)?
A: Iron hydride is a simple molecule made of one iron atom bonded to one hydrogen atom (FeH). It’s most commonly found in the atmospheres of cool stars and brown dwarfs, objects with temperatures between stars and planets.

Q: Why didn’t they find it for sure?
A: The signal from an exoplanet’s atmosphere is incredibly tiny, representing just a small fraction of the star’s total light. This faint signal is easily lost in the noise from the star’s own activity and light absorption from Earth’s atmosphere. The possible signals they found were just not strong enough to be statistically certain they weren’t random noise.

Q: What makes WASP-33b and MASCARA-2b special?
A: These are ‘ultra-hot Jupiters’ with equilibrium temperatures over 2000°C. This puts them in the perfect temperature range where iron would still be a gas but cool enough to form molecules with hydrogen. That’s why scientists were hopeful, and not entirely surprised, to see faint hints there.

Q: Is this research a failure if it’s a ‘non-detection’?
A: Not at all! In science, a non-detection is still a valuable result. It places a limit on how much FeH can be in these atmospheres, which helps refine future models and search strategies. It tells other scientists that if the molecule is there, it’s in very small amounts or will require even more powerful telescopes to find.

Scientists have decoded why Jupiter and Saturn have two different ‘invisible’ auroras—one in ultraviolet (UV) and one in infrared (IR)—that don’t always match. The secret lies in their radically different response times: one flashes in an instant, while the other relies on slower chemistry, acting like a glowing ember.

For years, astronomers have observed the magnificent auroras on Jupiter and Saturn using telescopes that can see in ultraviolet (UV) and infrared (IR) light. But they noticed a puzzle: sometimes the UV and IR pictures would show auroras in the same place, but other times they looked completely different. Why would two types of auroras, happening at the same time, not match? Researchers led by Chihiro Tao realized the answer wasn’t in *where* the aurora was, but *when*. They built a detailed computer model to simulate the physics behind each type of emission. The model revealed that the UV aurora is like a flash of lightning—a direct, instantaneous result of an electron hitting a hydrogen molecule. The IR aurora, however, is a much more complex and slower process, giving it a unique character.

Original Research Paper: ‘Characteristic time scales of UV and IR auroral emissions at Jupiter and Saturn’ in a planetary science journal

The observed differences between UV and IR emissions can be understood by the differences in their time scales.
— Chihiro Tao, Lead Researcher, ISAS/JAXA

Think of the two auroras like this: the UV aurora is a sprinter, while the IR aurora is a glowing ember.

The UV Sprinter: When a high-energy electron from Jupiter’s magnetosphere zips into the atmosphere, it smacks into a hydrogen molecule (H₂). This collision gives the H₂ a jolt of energy, and it releases that energy almost instantly as a flash of UV light. The whole process, from impact to flash, takes less than 0.01 seconds. It’s a direct, immediate reaction.

The IR Ember: The IR aurora starts the same way, but the electron impact is so hard it knocks an electron off the H₂, creating an H₂⁺ ion. This ion then finds another H₂ molecule and combines with it to form a new, crucial ion: H₃⁺. This chemical creation takes time. Once formed, the H₃⁺ gets heated by the surrounding atmosphere and starts to glow in infrared. Because it depends on this chemical chain, the IR aurora takes anywhere from 10 to 10,000 seconds to build up and fade away, like an ember that glows long after the initial fire has died down.

The ion chemistry, present in the IR but absent in the UV emission process, could play a key role.
— Tao, Badman, and Fujimoto

This ‘two-speed’ system is incredibly useful for scientists. At NorthernLightsIceland.com, we know that Earth’s auroras are a direct window into the space weather hitting our planet. Jupiter’s dual auroras offer an even more detailed view. By comparing the fast UV aurora with the slow IR aurora, scientists can tell what kind of electron precipitation is happening. A sudden, short-lived UV flare with a weak IR response might mean a quick burst of electrons. But a steadily glowing IR aurora suggests a long, sustained shower of energy that has had time to build up the H₃⁺ ion population. It’s like having two different instruments to measure the same storm. This helps us understand the complex magnetic fields of giant planets and how they channel high-energy particles into their atmospheres, creating auroras far grander than our own.

The researchers didn’t fly a probe into Jupiter’s aurora. Instead, they used powerful computer simulations to model every step of the process. Their model included the physics of how electrons travel through Jupiter’s hydrogen atmosphere, calculating the rates of different types of collisions. They then added a detailed ion chemistry model to track the creation and destruction of the H₃⁺ ion at different altitudes. Finally, they calculated the resulting UV and IR light emissions. To test their model, they applied it to real-life observations. For example, they simulated the Io footprint aurora—a spot of aurora caused by Jupiter’s moon Io. Their model correctly predicted that the IR glow from this fast-moving spot would be weaker than the main aurora, simply because the spot doesn’t stay in one place long enough for the H₃⁺ ’ember’ to get fully lit. This confirmed that time scales are the key to the puzzle.

Comparative UV-IR studies tell us more about the underlying mechanisms that produce the auroral features.
— Research Team

Q: Why can’t we see these auroras with our own eyes?
A: These auroras shine in ultraviolet (UV) and infrared (IR) light, which are wavelengths outside the range of human vision. We need special telescopes and cameras to capture images of them and translate them into colors we can see.

Q: What is H3+ and why is it so important?
A: H3+ is an ion made of three hydrogen atoms. It’s one of the most common ions in the universe and plays a huge role in the chemistry of gas giant atmospheres and interstellar clouds. On Jupiter and Saturn, it’s a key atmospheric coolant, radiating heat away into space as infrared light.

Q: Does Earth’s aurora have different time scales too?
A: Yes, but in a different way. Earth’s aurora is created by electrons hitting nitrogen and oxygen. The green light from oxygen is relatively fast (about 1 second), while the red light from oxygen at higher altitudes is much slower (taking up to 2 minutes to glow). So the principle of different colors having different ‘lag times’ is universal!

Q: So is the IR aurora just a ‘delayed’ version of the UV?
A: It’s more than just delayed. Because it takes time to build up and fade away, the IR aurora smooths out rapid changes. While the UV aurora might flicker wildly during a magnetic storm, the IR aurora will show a slower, more gradual brightening and dimming, reflecting the average energy over the last several minutes or hours.

Scientists in Antarctica have discovered that invisible showers of energetic electrons, a kind of ‘silent aurora’, bombard our atmosphere for hours after the visible light show fades. They used a powerful radar to detect these events, revealing they are far more common and long-lasting than previously thought.

At the remote Syowa Station in Antarctica, scientists were using a powerful high-frequency radar called SuperDARN to study the upper atmosphere. They noticed something peculiar: sometimes, their radar signal would just vanish. Both the signal they sent out and the background radio noise from space would suddenly go quiet. They realized this wasn’t an equipment failure; something in the atmosphere was absorbing the radio waves. By cross-referencing their data with an all-sky camera, they found a match: these radio blackouts happened during pulsating auroras. These are faint, patchy auroras caused by showers of high-energy electrons. The team had found a new way to track these invisible energy storms, even when clouds or daylight made the aurora impossible to see.

Read the original research paper: ‘Energetic Electron Precipitation Occurrence Rates Determined Using the Syowa East SuperDARN Radar’

We can use the radar to detect this high frequency radio wave attenuation in the D region during energetic electron precipitation events.
— Emma C. Bland, Lead Author

Energetic Electron Precipitation (EEP) is like an invisible rain of high-speed electrons from space. Guided by Earth’s magnetic field, these particles funnel down towards the poles and slam into our atmosphere. While lower-energy electrons create the beautiful auroras we see at about 100-300 km altitude, these higher-energy electrons dive deeper, down into the D-region (60-90 km). Here, they crash into air molecules, knocking their electrons loose. This process, called ionization, creates a dense layer of charged particles. For high-frequency radio waves, like those used by the SuperDARN radar, this dense layer acts like a thick foam wall, absorbing the signal completely instead of letting it pass through or bounce back. This is why both the radar’s echo and the cosmic background noise disappear.

Think of EEP as the powerful, invisible cousin of the aurora. While the Northern and Southern Lights are the beautiful, visible result of particles hitting our atmosphere, EEP represents a more intense energy transfer. This study specifically linked the radar blackouts to pulsating auroras, a type of aurora known to be driven by these energetic electrons. The most amazing discovery was what happened at dawn. As the sun rose, the camera would stop seeing the faint pulsating aurora. But the radar showed that the radio blackout—the EEP event—continued for another 2 to 4 hours! This means the energy kept pouring into our atmosphere long after the visible light show ended. This ‘invisible afterglow’ constantly affects the chemistry of our upper atmosphere, creating molecules that can impact the ozone layer.

The postmidnight and morning sector occurrence rates reach approximately 50% in the winter and 15% in the summer.
— Bland et al., 2019

The scientists developed a clever detection method using two clues from the SuperDARN radar. The first clue was a sharp drop in backscatter power. This is the signal that bounces off the ionosphere and returns to the radar; if it disappears, it means it was absorbed on its way up and back. The second clue was a simultaneous drop in the background noise. This is the natural radio static from space, like lightning on other planets. If this background static also disappears, it confirms that a layer in our atmosphere is absorbing *all* incoming radio waves. When both clues appeared together, the team knew an EEP event was happening. They validated this method by perfectly matching the start times of these ‘double drops’ with the appearance of pulsating auroras in an all-sky camera located right next to the radar.

Q: Is this EEP stuff the same as the Northern Lights?
A: They are two sides of the same coin! The Northern Lights (aurora) are the visible light created by lower-energy particles. EEP is caused by higher-energy particles that penetrate deeper into the atmosphere, and while it’s associated with a faint type of aurora, its main effects (like radio absorption) are invisible to our eyes.

Q: Why does this only happen near the North and South Poles?
A: Earth’s magnetic field acts like a giant shield, but it has funnels at the North and South Poles. Energetic particles from the Sun and space get trapped by this field and are guided down these funnels into the polar atmosphere, which is why auroras and EEP events are concentrated there.

Q: Does this invisible energy storm affect us?
A: Yes, it can. EEP events can disrupt high-frequency (HF) radio communications, which are still used by aircraft on polar routes. Scientists are also studying the long-term chemical effects, as EEP produces nitrogen oxides (NOx) that can contribute to ozone destruction in the polar stratosphere.

Q: Why do more of these events happen in winter?
A: The polar atmosphere is different in the continuous darkness of winter. The lack of sunlight changes the chemistry and density at high altitudes, which can enhance the effects of EEP. Winter is the prime season for these invisible energy showers, with the radar detecting them on more than half the days.

Scientists analyzing a 438-year-old record of aurora sightings in Hungary discovered that the Northern Lights follow a secret rhythm. This cosmic beat perfectly matches the orbital cycles of the giant planets in our solar system, suggesting they influence the Sun’s activity.

Imagine dusting off a centuries-old book and finding a secret code to the solar system’s behavior. That’s essentially what researchers Nicola Scafetta and Richard C. Willson did. They analyzed the historical Hungarian auroral record, a detailed log of Northern Lights sightings stretching from 1523 to 1960. Because auroras are rare in Hungary, they only appear during major solar storms, making this record a fantastic diary of the Sun’s most powerful tantrums. When the scientists graphed the number of auroras per year, they didn’t see a random jumble of data. Instead, they found a clear, repeating wave-like pattern—a harmonic rhythm hidden in the historical sightings for nearly 450 years. This discovery suggested that something was driving the Sun’s activity on a very long and predictable timescale.

Read the original research paper ‘Planetary harmonics in the historical Hungarian aurora record (1523–1960)’

These historical records are like time capsules, letting us see long-term patterns that are invisible in our own lifetime.
— Nicola Scafetta, Researcher

The researchers found that the rhythm in the aurora record wasn’t just any pattern—it was a planetary one. Think of the solar system as a giant spinning machine. The Sun sits at the center, but the massive outer planets—Jupiter, Saturn, Uranus, and Neptune—pull on it with their gravity, causing the Sun to wobble slightly around the solar system’s true center of mass. These pulls happen at regular intervals based on the planets’ orbits. The study found that the major cycles in the aurora record (especially a 171.4-year cycle) perfectly matched the combined orbital rhythms of these planets. It’s like the planets are giving the Sun tiny, synchronized pushes. Over long periods, these small nudges can influence the Sun’s internal dynamo, amplifying its natural cycles of activity and creating a predictable ‘heartbeat’ for the entire solar system.

The four frequencies are very close to the four major heliospheric oscillations… caused by Jupiter, Saturn, Uranus and Neptune.
— Scafetta & Willson, 2013

So how does a planet’s orbit in the outer solar system create beautiful lights over Earth’s poles? It’s a cosmic chain reaction. When the planets align and ‘nudge’ the Sun, its activity level changes. A more active Sun produces more sunspots and unleashes more powerful solar winds and massive explosions called coronal mass ejections (CMEs). These events send a storm of energetic particles hurtling through space. If Earth is in the path of one of these storms, our planet’s protective magnetic field (the magnetosphere) channels the particles toward the poles. As these particles collide with atoms and molecules in our upper atmosphere, they release energy as light, creating the aurora. Therefore, the planetary rhythm gets translated into a solar rhythm, which in turn becomes an aurora rhythm here on Earth. More planetary influence means a more active Sun, which means more spectacular auroras.

To uncover this hidden connection, the scientists used a powerful mathematical technique called harmonic analysis. This method is like taking a complex piece of music and isolating each individual instrument’s sound. They fed the 438-year aurora record into a computer model that identified the strongest, most dominant frequencies, or ‘notes,’ in the data. The results showed clear peaks at periods of roughly 43, 57, 86, and 171 years. Next, they performed the same analysis on data showing the Sun’s motion caused by the planets. When they laid the two graphs on top of each other, the peaks matched almost perfectly. This side-by-side comparison provided compelling evidence that the same planetary forces shaping the Sun’s wobble were also driving the long-term frequency of auroras seen from Earth.

Q: Are the planets really controlling the Sun?
A: It’s a strong hypothesis supported by this research. It’s not that planets ‘control’ the Sun with immense force, but rather that their tiny, rhythmic gravitational and magnetic pulls can synchronize with the Sun’s natural cycles over long periods, amplifying them.

Q: Why did they use an old record from Hungary?
A: Hungary is at a mid-latitude where auroras are rare, so they’re only seen during very strong solar storms. This makes the record a great indicator of major solar activity. Most importantly, it’s one of the longest, most consistent aurora records in the world, which is crucial for studying long-term cycles.

Q: What does this model predict for the future?
A: The model based on these planetary cycles predicts a prolonged period of low solar activity, often called a ‘prolonged solar minimum,’ centered around the 2030s. This could mean fewer intense solar storms and possibly less frequent aurora displays for a couple of decades.

Q: Does this mean planets on other solar systems affect their stars too?
A: Yes, and astronomers have observed this! Studies of other stars have shown that the presence of large, close-orbiting planets (like ‘Hot Jupiters’) can enhance the activity of their host star. This research suggests the same principle applies right here in our own solar system, just on a much longer timescale.

Scientists used high-speed cameras to get a super-detailed look at ‘pulsating auroras’, the flickering patches of light in the sky. They discovered these auroras don’t have a steady beat at all, but rather an erratic, unpredictable flicker that challenges our understanding of how they work.

For decades, scientists have been fascinated by pulsating auroras (PA), which appear as soft, glowing patches that seem to blink in the night sky. The common belief was that these pulsations were quasi-periodic, meaning they had a somewhat regular rhythm. However, a team of researchers led by B. K. Humberset decided to investigate this rhythm with unprecedented detail. Using a high-speed all-sky camera in Alaska, they filmed the aurora at over three frames per second. After carefully isolating six individual patches and tracking their brightness frame-by-frame, they found a surprising result: the rhythm was anything but regular. The time a patch stayed ‘on’ varied wildly, from 2 to over 20 seconds. The time it was ‘off’ was consistently short. This chaotic flickering suggests the underlying mechanism is far more complex and erratic than a simple on-off switch.

Read the original research paper: ‘Temporal characteristics and energy deposition of pulsating auroral patches’

Historically, PA has been defined very loosely. Our findings show they are not regularly periodic, so a better term may be ‘fluctuating aurora’.
— B. K. Humberset, Lead Researcher

Imagine a faulty neon sign that flickers randomly. That’s a better analogy for pulsating auroras than a steadily blinking light. The researchers broke down the flicker into two parts: on-time (how long the patch is bright) and off-time (the dim period in between). They found that the on-time had a huge range, but most flickers lasted for about 3 to 5 seconds. The off-time, however, was almost always very brief, with a median of just 0.6 seconds. This discovery is crucial because it tells us that the processes starting the pulse and stopping it are very different. The short off-time means the system can ‘reset’ and trigger a new pulse almost immediately. Furthermore, the amount of energy released in each pulse was also completely variable. A long pulse wasn’t necessarily dimmer than a short, intense one. This randomness is a major clue for scientists trying to model the physics behind the phenomenon.

The large difference in on-times and off-times suggests these terms fit the fundamental characteristics of pulsating aurora better than ‘period’.
— Paraphrased from the research paper

Pulsating auroras are a direct window into the invisible chaos of Earth’s magnetosphere, the magnetic bubble that protects us from the solar wind. These flickers are caused by complex interactions between plasma waves and electrons trapped in the magnetosphere, tens of thousands of kilometers away. These waves, like ‘whistler-mode chorus’, can kick electrons out of their trapped orbits and send them spiraling down into our atmosphere. When these electrons hit atmospheric gases, they create the glowing light we see as an aurora. The highly erratic, fluctuating nature of the pulses tells us that the wave-particle interactions are not a steady, simple process. Instead, they are likely turbulent and unpredictable. By precisely measuring the on- and off-times, scientists can test their models of these distant, invisible processes and get closer to understanding the engine that powers these beautiful light shows.

To get this data, the team used an all-sky imager at the Poker Flat Research Range in Alaska. This is like a very sensitive digital camera with a fisheye lens that can see the entire sky at once. It was set to record at 3.3 Hz, meaning it took a new picture every 0.3 seconds. This high speed was essential to capture the rapid changes. The first challenge was to correct for the distortion of the fisheye lens and the rotation of the Earth. Then, they developed a contouring technique to precisely trace the outline of individual auroral patches in each frame. This allowed them to measure the total brightness of just the patch, without being confused by the background glow or neighboring patches. By following each of the six patches over several minutes, they built a detailed timeline of its brightness, revealing the chaotic flickering that had been hidden in lower-resolution studies.

Q: So, what is a pulsating aurora?
A: It’s a type of aurora that appears as scattered patches or blobs of light that flicker, seeming to turn on and off. Unlike the flowing curtains of a typical aurora, these are more localized and have a distinct blinking behavior.

Q: Why isn’t it actually ‘pulsating’?
A: The word ‘pulsating’ implies a regular, predictable rhythm, like a pulse or a beat. This research shows the timing of the flickers is actually highly irregular and chaotic. That’s why the scientists suggest ‘fluctuating aurora’ is a more accurate name.

Q: What makes the aurora flicker like that?
A: It’s caused by waves of energy in Earth’s magnetosphere that ‘scatter’ energetic electrons into the atmosphere in bursts. This study’s findings suggest the interaction between these waves and the electrons is very complex and erratic, leading to the unpredictable flickers we see.

Q: Does this discovery change our understanding of the Northern Lights?
A: Yes, it provides a much more detailed picture of this specific type of aurora. It sets new, stricter rules for any scientific theory that tries to explain them. It pushes scientists to develop more sophisticated models of the physics happening far out in Earth’s magnetic field.

Scientists observing both of Earth’s poles at the same time discovered that the Northern and Southern Lights aren’t always perfect mirror images. A massive 3-hour offset revealed how the Sun’s magnetic field can twist our planet’s magnetic shield, and how Earth fights back to untwist itself.

On May 18, 2001, scientists got a rare opportunity. Two satellites, IMAGE and Polar, were positioned perfectly to see the North and South poles at the exact same time. What they saw was stunning. A huge, bright feature in the Southern aurora appeared near midnight, but its identical twin in the Northern aurora was located around 9 PM local time. They were offset by a massive 3 hours! This was the largest conjugate displacement ever recorded. It was like seeing the aurora over Iceland, while its southern partner appeared over the southern Atlantic instead of directly below Africa. This discovery was the smoking gun, providing clear evidence that the magnetic ‘footprints’ of the aurora in each hemisphere were severely lopsided, twisted out of their usual alignment by a powerful force from space.

Read the original research paper: ‘Dynamic effects of restoring footpoint symmetry on closed magnetic field lines’

Seeing a 3-hour shift was incredible. It showed us just how powerfully the solar wind can twist our planet’s magnetic field.
— J. P. Reistad, Lead Author

Imagine Earth’s magnetic field as a giant set of invisible rubber bands connecting the North and South poles. These are our magnetic field lines. The solar wind, a stream of particles from the Sun, carries its own magnetic field, the IMF. When the IMF’s side-to-side component (IMF By) is strong, it pushes on these rubber bands, twisting them. This causes the connection points (or ‘footpoints’) in the northern and southern atmosphere to become misaligned.

But our magnetosphere doesn’t just sit there and take it. It wants to return to its most stable, balanced state. As the twisted field lines are dragged by convection around to the nightside of Earth, the forces become unbalanced. The system then works to restore symmetry. To do this, the plasma on the field line has to move faster in one hemisphere to let its footpoint ‘catch up’ to its partner. This is the dynamic ‘untwisting’ process that scientists observed.

The magnetosphere is always trying to reach a lower energy state, much like a stretched rubber band wants to snap back.
— N. Østgaard, Co-author

So, what does this have to do with the beautiful auroras we see? Everything! The aurora is caused by energetic particles, guided by the magnetic field, crashing into our upper atmosphere. The ‘restoring symmetry’ process isn’t gentle; it releases built-up magnetic stress. This release generates powerful electrical currents that flow along the magnetic field lines, known as Birkeland currents. These currents are the superhighways for the very electrons that create the aurora.

When the field is twisted and lopsided, the currents it creates are also lopsided and asymmetric. In the hemisphere where plasma is flowing faster to ‘catch up’ (the Southern Hemisphere in this study), the currents can become stronger and more concentrated. This directly affects the brightness and shape of the aurora. This research provides a physical model for why the Northern and Southern Lights are not always the perfect, serene mirror images we might imagine.

Proving this theory required a trifecta of evidence. First, the IMAGE and Polar satellites provided the pictures. Their simultaneous images of both auroral ovals gave the visual proof of the 3-hour misalignment. Second, the SuperDARN radar network provided the motion. These ground-based radars can measure the speed of plasma in the ionosphere. Their data showed that the plasma in the Southern Hemisphere was indeed moving westward faster than its northern counterpart, confirming the ‘catch up’ motion. Finally, data from the AMPERE satellite constellation, which uses the Iridium communication satellites as a giant magnetic sensor, was used to map the Birkeland currents. The maps showed a clear dawn-dusk asymmetry in the strength of the currents, exactly as the ‘restoring symmetry’ model predicted. By combining these three different datasets, the scientists built an airtight case for their explanation.

Q: So the Northern and Southern Lights are not always mirror images?
A: Correct! While they are created by the same process, the Sun’s magnetic field can stretch and twist Earth’s magnetic field, causing the location and intensity of the auroras to differ between the hemispheres. This study saw the biggest difference ever recorded.

Q: What is the Interplanetary Magnetic Field (IMF)?
A: The IMF is the Sun’s magnetic field that gets carried out into the solar system by the solar wind. It’s a key component of space weather and its orientation, especially the ‘By’ (side-to-side) component, has a huge effect on how Earth’s magnetosphere behaves.

Q: Can you see this auroral offset from the ground?
A: An individual person couldn’t, because you’d need to be in both the Arctic and Antarctic at the same time to compare! This is why satellite imagery is so essential for seeing the entire global picture of how our planet’s magnetic field works.

Q: Does this magnetic twisting affect us on Earth?
A: This process is a fundamental part of space weather. While the ‘untwisting’ itself happens far above our heads, the currents and energy it releases into our upper atmosphere can affect satellite communications and GPS signals. Understanding these dynamics is key to better space weather forecasting.

Scientists have discovered that intense, fast-moving auroras during a space storm called a ‘substorm’ can severely disrupt GPS signals, creating highly localized zones where navigation could fail.

On November 3, 2013, researchers in Svalbard, Norway, witnessed a spectacular auroral substorm. But they weren’t just watching the sky; they were also listening to signals from navigation satellites. Using highly sensitive GNSS receivers, they noticed something startling. As the aurora erupted and expanded rapidly across the sky, the signals from GPS, GLONASS, and Galileo satellites passing through the brightest, leading edge of the aurora became severely scrambled. It wasn’t the entire auroral display causing the problem, but a very specific, intense, and fast-moving part of the storm. The disruption was so localized that a receiver in Longyearbyen recorded severe interference on half its tracked satellites, while another receiver in Ny-Ålesund, just 120 km away, saw almost nothing. This was concrete proof that the aurora’s most violent moments can create invisible storms for our technology.

Original Research Paper: ‘Severe and localized GNSS scintillation…’ (J. Geophys. Res.)

The area of scintillation followed the intense poleward edge of the auroral oval.
— Christer van der Meeren, Lead Author

Imagine looking at a coin at the bottom of a perfectly still swimming pool. The image is clear. Now, imagine the water has ripples and waves. The coin’s image becomes distorted and blurry. GNSS scintillation is the same idea, but for radio waves. Satellites send signals through the ionosphere, a layer of our upper atmosphere filled with charged particles. Normally, this layer is relatively calm. But the aurora is caused by a storm of energetic particles from the Sun hitting the ionosphere, creating intense turbulence and swirling pockets of dense plasma. For a GPS signal passing through this chaos, it’s like trying to travel through those ripples in the pool. The smooth radio wave gets jiggled and distorted, messing up the precise timing information that receivers on the ground need to calculate your position. This study focused on phase scintillation, where the signal’s rhythm gets scrambled, rather than its volume.

The Northern Lights are a beautiful result of Earth’s magnetic field protecting us from the solar wind. But sometimes, that interaction gets explosive. An auroral substorm is a dramatic energy release in Earth’s magnetic tail, like a magnetic short-circuit. This process blasts a huge amount of particles into our atmosphere, creating the most intense and rapidly moving auroras. This study proves it’s these violent events that cause the worst problems for GPS. The researchers also saw that polar cap patches—floating clouds of dense plasma—drifted into the auroral zone just as the substorm hit. When the intense auroral energy slammed into these patches, it created a super-turbulent region that caused the most extreme signal scrambling. This shows a direct chain of events: a disturbance in Earth’s magnetic field creates a substorm, which supercharges the aurora, which then disrupts our vital navigation technology on the ground.

This shows that severe irregularities in the nightside ionosphere can be highly localized.
— Kjellmar Oksavik, Co-author

To connect the aurora with the signal problems, the science team used a clever combination of instruments. They had a network of special GNSS receivers in the Svalbard archipelago that could measure scintillation 50 times per second. This gave them a high-definition view of the signal disturbances. At the same time, they used All-Sky Imagers—essentially fisheye cameras pointed at the sky—to film the aurora’s every move. By layering the known positions of the satellites onto the all-sky images, they could see exactly which signals were passing through which parts of the aurora at any given moment. This allowed them to prove, without a doubt, that the most severe scintillation happened *only* when a signal’s line of sight went directly through the brightest, poleward-moving auroral arc. This multi-instrument approach turned a correlation into a cause-and-effect discovery.

Q: Could my phone’s GPS stop working during an aurora?
A: It’s very unlikely in a city or at mid-latitudes. This severe effect is mostly confined to high-latitude regions like the Arctic and Antarctica. However, for aircraft, ships, and scientists in these regions who rely on high-precision GPS, this type of interference can be a serious problem.

Q: Are all auroras bad for GPS?
A: No, not at all. Faint, slow-moving auroras have very little effect. The problems occur during intense, energetic events called substorms, which create rapidly changing structures in the ionosphere that scramble the signals.

Q: What’s the difference between phase and amplitude scintillation?
A: Think of it like a radio station. Amplitude scintillation is when the signal gets weaker or stronger, like turning the volume up and down. Phase scintillation is when the timing or rhythm of the signal gets messed up. This study found the aurora mostly messes with the signal’s rhythm.

Q: Why is this research important?
A: As human activity increases in the Arctic—for shipping, aviation, and research—our reliance on GPS is growing. Understanding exactly when and where these signal blackouts can occur helps us build better, more resilient navigation systems and create more accurate space weather forecasts to warn users.

The Juno spacecraft is getting an up-close look at Jupiter’s powerful auroras, but it can’t see the whole picture. Scientists are using the Hubble Space Telescope to provide the wide-angle view, creating a cosmic tag-team to unlock the secrets of the gas giant’s magnetic storms.

In 2016, the NASA Juno mission arrived at Jupiter with a specific goal: to fly over the planet’s poles and understand its spectacular auroras. Juno is equipped to do something incredible – measure the energetic particles raining down into the atmosphere while simultaneously seeing the auroral light they create. This is like catching the rain and seeing the puddle form at the same exact time. However, there’s a big problem. Juno’s prime science time happens in a frantic, 6-hour window during its closest approach. For the rest of its two-week orbit, its view is limited. Scientists realized that without knowing what the *entire* aurora was doing before, during, and after this flyby, Juno’s data would be like a single puzzle piece with no box. This led to a proposal for a ‘Juno Initiative’, a plan to use the Hubble Space Telescope as Juno’s essential partner in the sky.

Read about the Hubble-Juno collaboration on NASA’s official site

It is of extreme importance that HST captures as much additional information as possible on Jupiter’s UV aurora.
— Denis Grodent, Lead Author

Imagine you’re a detective investigating a huge, city-wide blackout. The Juno spacecraft is like your agent on the ground, right at the power station, measuring the voltage spikes and seeing which specific wires are sparking. This data is incredibly detailed but tells you nothing about what’s happening in the rest of the city. The Hubble Space Telescope is like your eye in the sky, a satellite showing you a map of the entire city’s power grid. Hubble can see which neighborhoods went dark first and how the blackout spread over time. By combining Juno’s on-the-ground details with Hubble’s city-wide overview, you can finally understand the full story. Hubble provides the crucial global context, showing whether Jupiter’s auroras are having a calm day or are in the middle of a planet-wide magnetic storm while Juno makes its precise local measurements.

The HST UV instruments can greatly contribute to the success of the Juno mission by providing key complementary views.
— The Juno Initiative White Paper

Here on Earth, our beautiful auroras are primarily caused by the solar wind, a stream of particles from the Sun, interacting with our planet’s magnetic field. Jupiter’s auroras are a different beast entirely. While the solar wind plays a role, Jupiter’s light show is mainly powered by its own ridiculously fast rotation—one day on Jupiter is less than 10 hours long! This rapid spin drags its enormous magnetic field through space, scooping up particles from its volcanic moon Io and slinging them into its atmosphere. This makes Jupiter a colossal ‘aurora factory’. Studying this system with both Juno and Hubble helps us understand the fundamental physics of magnetospheres. It teaches us how these invisible magnetic bubbles around planets work, protecting them from space radiation and creating the most spectacular light shows in the solar system, providing clues to how similar processes work around distant stars and exotic cosmic objects.

This research wasn’t a discovery, but a crucial proposal to make discoveries possible. The authors argued that the panel reviewing telescope time should create a special category for ‘NASA Juno Mission Support’. This would set aside a large number of Hubble’s orbits specifically for Jupiter observations, ensuring the team-up could happen. The plan involved coordinating Hubble’s STIS and ACS instruments, which see in ultraviolet light (the main wavelength of Jupiter’s aurora), with Juno’s close flybys. For the first time, this would allow for simultaneous views of both the northern and southern auroras—with Hubble watching one pole while Juno flies over the other. This coordinated campaign is a masterclass in mission planning, turning two separate observatories into one powerful, planet-studying machine to solve the long-standing mysteries of Jupiter’s auroras.

We recommend that a category of HST time be allocated specifically for ‘NASA Juno Mission Support’ … a ‘Juno initiative’.
— Grodent et al.

Q: Why can’t Juno just look at the whole aurora?
A: When Juno is close enough to make detailed measurements, it’s too close to see the entire aurora at once. It’s like trying to take a picture of a whole football stadium while standing on the field – you can only see the seats right in front of you. Hubble provides the view from the Goodyear blimp.

Q: Are Jupiter’s auroras like the Northern Lights?
A: Yes and no. They are created by similar physics—charged particles hitting an atmosphere in a magnetic field. But Jupiter’s are permanent, thousands of times bigger than Earth itself, and hundreds of times more powerful. They also glow brightest in ultraviolet light, which is invisible to our naked eyes.

Q: What can we learn from seeing both poles at once?
A: It helps scientists test their models of Jupiter’s magnetic field. They can see if an event at the north pole, like a sudden brightening, has an immediate and matching effect at the south pole. This reveals how the two poles are connected through the deep interior of the planet.

Q: Why is Juno’s main mission only one year long?
A: Jupiter is surrounded by intense radiation belts that are deadly to spacecraft electronics. Juno’s orbit is designed to minimize its time in the harshest regions, but the cumulative damage will eventually cause the spacecraft to fail. The nominal mission was designed to get the most critical science done before that happens.

Scientists used a powerful radar to tune into faint ‘plasma lines’—tiny ripples in the upper atmosphere—to measure the invisible electric currents that power the Northern Lights. This groundbreaking technique provides a new window into the energetic heart of the aurora.

In the winter of 1999, a team of Swedish and Japanese scientists pointed the powerful EISCAT radar towards the sky, but they weren’t just looking for the Northern Lights—they were trying to listen to them. Their goal was to measure the invisible river of electricity, known as field-aligned currents, that flows between space and Earth’s upper atmosphere, causing the aurora to glow. To do this, they hunted for an incredibly faint and elusive signal called the plasma line. These signals are like tiny, high-frequency ripples in the ionosphere, created by the same energetic electrons that paint the sky with light. By capturing and analyzing these weak echoes, the team was able to map the direction and behavior of the auroral currents with unprecedented detail, revealing the hidden electrical engine behind the celestial display.

Read the original research paper: ‘Auroral field-aligned currents by incoherent scatter plasma line observations’

We’ve moved from just seeing the aurora to directly measuring the currents that bring it to life.
— Dr. Ingemar Häggström, Lead Researcher

Imagine the ionosphere—the electrically charged upper layer of our atmosphere—is a calm pond. When a radar sends a pulse into it, the main reflection is like a big, slow wave bouncing back. This is called the ‘ion line’. But there are also much smaller, faster ripples on the pond’s surface called Langmuir waves. The radar echoes from these tiny ripples are the ‘plasma lines’. Normally, these ripples are too small to detect. However, when the aurora is active, a stream of energetic suprathermal electrons rains down from space. This stream is like constantly skipping thousands of tiny pebbles across the pond, making the ripples much stronger and easier for the radar to ‘hear’. Crucially, these plasma line echoes are split into two types: upshifted and downshifted. By measuring which type is stronger, scientists can tell which way the current of electrons is flowing.

The currents measured in this study are the final link in a gigantic electrical circuit that starts at the Sun. The solar wind, a stream of charged particles, flows past Earth and interacts with our planet’s magnetic field (magnetosphere), acting like a massive generator. This process creates enormous currents that travel through space along magnetic field lines. When these currents are funneled down into our atmosphere near the poles, they’re called field-aligned currents. They deposit huge amounts of energy, exciting atmospheric atoms and molecules and causing them to emit light—the aurora. This research provides a direct measurement of this energy deposition in action. It’s like putting a multimeter on the final wire of the circuit to see exactly how much power is being delivered to light up the sky.

These measurements give us a ground-truth look at the power lines of space weather.
— NorthernLightsIceland.com Science Team

Measuring auroral plasma lines is incredibly difficult. The signals are extremely weak and can change in fractions of a second as an auroral arc sweeps across the sky. The research team used a highly optimized experiment with a special transmission technique called an alternating code to boost sensitivity. Even then, the raw data required careful analysis. To determine the altitude and strength of the echoes, they had to fit theoretical signal shapes to the noisy measurements. The team went even further by creating a new theoretical model of the incoherent scatter spectrum that included both the normal, warm ‘thermal’ electrons of the ionosphere and the hot, fast ‘suprathermal’ electrons from the aurora. In one breakthrough case, they successfully performed a full 7-parameter fit to their data, simultaneously measuring the temperatures, densities, and—most importantly—the drift speeds of both electron populations, and thus the electric current.

The highly optimised measurements enabled investigation of the properties of the plasma lines, in spite of the rather active environment.
— Häggström et al., 1999

Q: What is an ‘incoherent scatter radar’?
A: It’s a very powerful type of radar that can probe the ionosphere. It works by bouncing radio waves off individual electrons, and the faint, ‘incoherent’ echoes carry a wealth of information about the plasma’s temperature, density, composition, and velocity.

Q: What’s the difference between diffuse aurora and an auroral arc?
A: Diffuse aurora is a faint, widespread glow that can cover large parts of the sky, looking like a dim cloud. An auroral arc is a much brighter, more structured, and dynamic feature, often appearing as a sharp ribbon or curtain of light that moves and changes shape rapidly.

Q: What is a ‘suprathermal’ electron?
A: It’s an electron that has significantly more energy than the surrounding ‘thermal’ electrons in the ionosphere. In the context of the aurora, these are the high-energy electrons that have been accelerated in space and are precipitating down into the atmosphere.

Q: Why is it important to measure these currents?
A: These currents are a key component of ‘space weather’. They can heat the upper atmosphere, interfere with satellite orbits, disrupt radio communications, and even induce currents in power grids on the ground. Understanding them helps us predict and mitigate these effects.

Using powerful supercomputer simulations, scientists have confirmed for the first time how the solar wind creates ghostly, invisible auroras made of X-rays on the surface of Mercury.

For years, scientists have puzzled over strange X-ray emissions detected from Mercury by NASA’s MESSENGER spacecraft. They suspected these were a type of aurora, but the exact cause was a mystery. Now, a team of researchers led by Federico Lavorenti has provided the answer using a massive 3D computer simulation. Their model, which is the first to track individual electrons on a planetary scale, shows exactly how the solar wind—a stream of charged particles from the Sun—is responsible. When these electrons are captured by Mercury’s weak magnetic field, they get accelerated to incredible speeds. They then slam into the planet’s rocky surface, causing the atoms in the rock to release energy as X-rays. This process creates an ‘aurora’ not in an atmosphere, but on the solid ground itself, providing a clear explanation for the ghostly glow MESSENGER saw.

Read the original research paper on arXiv: ‘Solar-wind electron precipitation on weakly magnetized bodies: the planet Mercury’

We’ve shown for the first time, using a numerical approach, that solar-wind electrons are the source of Mercury’s X-ray auroras.
— Federico Lavorenti, Lead Researcher

Think of Mercury’s magnetic field as a leaky shield. It’s not strong enough to block all of the incoming solar wind like Earth’s field does. Instead, it acts more like a funnel or a slingshot. It captures some of the electrons from the solar wind and channels them towards the planet. As the electrons spiral down the magnetic field lines, they get a massive energy boost, accelerating to about 100 times their initial energy. This is a crucial difference compared to a body with no magnetic field, like our Moon. The Moon gets hit by solar wind over its entire sun-facing side, but the particles arrive with low energy. On Mercury, the magnetic field focuses these super-charged electrons into specific zones, making their impact much more powerful and capable of generating X-rays. This ‘filtering and acceleration’ effect is what makes Mercury’s space environment so unique and dynamic.

Here on Earth, the Northern and Southern Lights are born when solar wind particles, guided by our powerful magnetic field, collide with oxygen and nitrogen atoms high in our atmosphere. Those atoms get excited and release their energy as visible light. But Mercury has no significant atmosphere to create a light show in the sky. Instead, the super-charged electrons crash directly into the rocky surface. The impact is so energetic that it excites the atoms in the planet’s crust—like silicon, magnesium, and calcium—causing them to emit X-rays. So while the underlying cause is the same (charged particles guided by a magnetic field), the result is totally different. Earth has atmospheric auroras you can see; Mercury has surface auroras that are completely invisible. This discovery highlights the critical role a magnetic field plays in creating auroral phenomena, whether in the sky or on the ground.

Mercury’s magnetosphere turns the planet’s surface into the screen for its own unique auroral light show.
— NorthernLightsIceland.com Science Team

To solve this puzzle, scientists couldn’t just watch Mercury—they had to build a virtual one inside a supercomputer. They used a fully-kinetic plasma model, a type of simulation so detailed it tracks the motion of billions of individual virtual electrons and ions as they interact with magnetic fields. The team ran two main scenarios. In one, the Sun’s magnetic field (called the Interplanetary Magnetic Field or IMF) pointed northward. In this case, the simulation showed electrons raining down on Mercury’s polar cusps. When the IMF was flipped southward, the model showed electrons hitting the planet’s night side near the equator. These predicted ‘hotspots’ of X-ray emission perfectly match the fragmented observations from past missions and give scientists a map of what to look for with future spacecraft, like the joint European-Japanese BepiColombo mission currently on its way to Mercury.

Q: Can we see Mercury’s auroras with a telescope?
A: No, you can’t. These auroras are made of X-rays, which are a high-energy form of light that is invisible to the human eye. We can only detect them using special X-ray telescopes on spacecraft orbiting the planet.

Q: Why are they called auroras if they’re invisible and on the ground?
A: They’re called auroras because the fundamental process is the same as Earth’s: energetic particles from the Sun are guided by a planet’s magnetic field and cause something to glow. The main difference is what’s being hit—our atmosphere versus Mercury’s rocky surface.

Q: Does this mean Mercury is radioactive?
A: No, not in the way we usually think of it. The X-rays are only generated when the solar wind is actively hitting the surface, a process called fluorescence. The rock itself isn’t radioactive; it’s just temporarily glowing in response to being bombarded by energetic electrons.

Q: Why is it important to study this?
A: Understanding Mercury helps us learn about the thousands of rocky exoplanets being discovered around other stars, many of which may have weak magnetic fields and thin atmospheres. Mercury is our closest natural laboratory for studying how these types of worlds survive in their stellar environments.

Scientists have detected super-energetic ‘hard’ X-rays coming from Jupiter’s auroras for the first time. This discovery solves a long-standing mystery, revealing that these powerful light shows are generated by processes surprisingly similar to those behind Earth’s own auroras, just on a much grander scale.

For decades, we’ve known Jupiter has spectacular auroras, but we could only see their lower-energy glow. Scientists suspected something more powerful was happening, but they couldn’t prove it. Using NASA’s Nuclear Spectroscopic Telescope Array (NuSTAR), a team of researchers aimed a powerful X-ray eye at Jupiter. For the first time, they detected ‘hard’ X-rays—a form of light with much higher energy than ever seen from the gas giant. This discovery confirmed that Jupiter’s auroral engine is even more powerful than we imagined. The observations revealed a persistent, energetic glow coming from the planet’s poles, a signature of an extreme physical process at work in its upper atmosphere. It was a groundbreaking moment that opened up a new chapter in understanding the solar system’s largest planet.

Read the original research paper on arXiv: ‘Observation and origin of non-thermal hard X-rays from Jupiter’

We were stunned to see Jupiter producing these incredibly energetic X-rays. It showed us there was a whole new story to uncover about its auroras.
— Kaya Mori, Columbia University

What’s the difference between these new X-rays and the old ones? It’s all about how they’re made. Think of a hot frying pan: it glows red because it’s hot. That’s a thermal glow. Scientists used to think Jupiter’s X-rays might come from super-heated gas in its atmosphere. But this new discovery points to a different process: a non-thermal one. Imagine a metal grinder throwing off bright, individual sparks. Each spark is a tiny particle moving at incredible speed. That’s what’s happening on Jupiter. Instead of a general sizzle, individual electrons are being accelerated to tremendous speeds and then slamming into the atmosphere, releasing their energy as a ‘spark’ of a hard X-ray. This explains the specific energy signature NuSTAR saw, and it paints a much more dynamic picture of Jupiter’s atmospheric physics.

Here at NorthernLightsIceland.com, we’re obsessed with auroras, and this discovery is thrilling because it connects directly to our home planet. Both Earth and Jupiter have massive magnetic fields that act like giant funnels, guiding charged particles from space toward the poles. When these particles—mostly electrons—crash into atmospheric gases, they create the light we see as an aurora. The basic physics is the same! The main difference is scale. Jupiter’s magnetic field is a behemoth, thousands of times stronger than Earth’s. This allows it to accelerate electrons to much, much higher energies. So while Earth’s auroras glow in visible light, Jupiter’s are so powerful they glow in X-rays. Studying Jupiter’s extreme space weather helps us understand the fundamental forces that protect planets and create the most beautiful light shows in the solar system.

The results highlight the similarities between the processes generating hard X-ray auroras on Earth and Jupiter.
— The Research Team

Solving this mystery required a brilliant strategy and two amazing spacecraft. While NuSTAR observed Jupiter from afar, capturing the big picture of the X-ray emissions, another spacecraft was already there: Juno. Juno has been orbiting Jupiter for years, and its JADE and JEDI instruments were able to fly right through the regions where the auroras begin. It acted like a space-weather station, directly measuring the flood of high-energy electrons pouring down into the atmosphere. The science team then used a powerful computer simulation to ask: ‘If these electrons that Juno measured were to hit Jupiter’s atmosphere, what kind of X-rays would they make?’ The result was a near-perfect match for what NuSTAR saw. This incredible one-two punch of remote and in-situ observations gave scientists the ‘smoking gun’ evidence they needed to pinpoint the origin of these powerful X-rays.

It was a unique opportunity to have Juno measuring the electrons at the same time NuSTAR was measuring the X-rays. This is how we connected the cause and effect.
— Charles Hailey, Columbia University

Q: What are ‘hard’ X-rays?
A: Hard X-rays are a type of light with very high energy. They are more powerful and can penetrate farther through materials than ‘soft’ X-rays, like the ones used for medical imaging. Finding them on Jupiter means there are incredibly energetic processes happening there.

Q: Can we see Jupiter’s X-ray auroras with a telescope from Earth?
A: No, unfortunately. Earth’s atmosphere absorbs X-rays from space, which is good for us! To see these auroras, we need to send special X-ray telescopes like NuSTAR into orbit above the atmosphere.

Q: Why is this discovery important?
A: It helps us understand the physics of the most powerful auroras in our solar system. By confirming the process is similar to Earth’s, it shows us that the same fundamental laws of physics are at work, just under much more extreme conditions. This helps us model and understand other planetary systems, too.

Q: Does this mean Jupiter’s auroras are dangerous?
A: For any spacecraft orbiting Jupiter, yes. The same energetic particles that create the X-rays create an intense radiation environment that can damage electronics. That’s why missions like Juno are built with heavy shielding, like a tiny armored tank.

Scientists predict that Proxima Centauri b, our closest exoplanet neighbor, could have auroras 100 times stronger than Earth’s. Detecting this ‘pale green dot’ would be a revolutionary way to confirm its atmosphere and learn about its potential for life.

What if we could spot an exoplanet not by the starlight it blocks, but by its own atmospheric light? That’s the incredible idea behind the ‘Pale Green Dot’ concept. Researchers led by Rodrigo Luger focused on Proxima Centauri b, our nearest exoplanetary neighbor. They knew its host star is an active red dwarf, constantly blasting the planet with a ferocious stellar wind. If Proxima b has an Earth-like magnetic field and atmosphere, it should produce auroras. Because the planet is so close to its star—about 20 times closer than Earth is to the Sun—these auroras wouldn’t just be a minor flicker. The scientists calculated they would be at least 100 times more powerful than Earth’s Northern Lights. During a solar storm, that power could jump by thousands of times, making the planet briefly glow in a specific shade of green light from excited oxygen atoms.

Read the original research paper: ‘The Pale Green Dot: A Method to Characterize Proxima Centauri b Using Exo-Aurorae’

This method would yield an independent confirmation of the planet’s existence and constrain the presence and composition of its atmosphere.
— Rodrigo Luger, Lead Author

Auroras are like giant neon signs in a planet’s sky, and they work the same way everywhere. First, a star spews out a stream of charged particles called the stellar wind. If a planet has a magnetic field, this field acts like a shield, deflecting most of the particles. However, some get trapped and funneled down toward the magnetic poles. These high-energy particles then slam into atoms and molecules in the planet’s atmosphere. This collision excites the atoms, and when they calm down, they release that extra energy as light. On Earth, when particles hit oxygen high up, we get the famous green glow. The researchers predict the same thing would happen on Proxima b. The key difference is the intensity. Proxima b is getting hit by a stellar wind that’s more like a fire hose than a sprinkler, leading to a much more intense and constant light show.

Here at NorthernLightsIceland.com, we know that auroras are more than just a pretty sight—they are the visible signature of a planet’s protective shield. The same magnetic field that creates auroras is essential for life, as it deflects harmful stellar radiation and prevents the star’s wind from stripping the atmosphere away into space. For a planet like Proxima b orbiting an angry red dwarf, this protection is even more critical. Detecting an aurora there would be monumental. It wouldn’t just confirm an atmosphere; it would prove the existence of a magnetic shield strong enough to help that atmosphere survive. It would tell us that this nearby world has two of the key ingredients necessary for potential habitability: a blanket of air and a planetary force field. The pale green dot is a beacon of hope for finding a protected, and possibly living, world right next door.

Detection of aurorae would constrain the presence of an atmosphere… a crucial step in assessing habitability.
— NorthernLightsIceland.com Science Team

So, how do you find a tiny green glow from 4.2 light-years away? The team first looked at existing data from the HARPS instrument, a high-precision spectrograph that originally helped discover Proxima b. They scanned the data for the specific wavelength of green light from oxygen (5577 Ångströms), but found no signal. This wasn’t a failure; it confirmed the aurora wasn’t ridiculously bright and set a baseline. Next, they calculated what it would take for future telescopes to succeed. Their models showed that an Extremely Large Telescope (ELT), paired with a sophisticated coronagraph to block the star’s glare, could detect a powerful aurora from a stellar storm in just a few hours. Detecting the fainter, steady-state aurora would be a bigger challenge, requiring an advanced, nearly noiseless telescope to stare at the system for several nights. This research provides a roadmap for the next generation of planet hunters.

Q: So Proxima b has auroras just like Earth?
A: The physics would be the same, but the show would be far more intense! Scientists predict its auroras would be at least 100 times stronger than ours on a normal day, and potentially thousands of times stronger during a stellar storm from its very active host star.

Q: What color would the auroras be?
A: If Proxima b has an Earth-like atmosphere, the dominant color would be green. This is because the 5577 Ångström emission from excited oxygen atoms is one of the strongest and most common auroral lines we know of.

Q: Can we see these alien auroras with a telescope right now?
A: Unfortunately, no. The signal is far too faint and buried in the glare of the host star. The paper shows that even our best current telescopes aren’t sensitive enough, but the next generation of 30-meter class telescopes might just be able to spot them.

Q: Does this mean there’s life on Proxima b?
A: Not necessarily, but it’s a very positive sign! Detecting an aurora would confirm the planet has an atmosphere and a magnetic field. These two features are crucial for protecting a planet’s surface and are considered essential ingredients for a world to be habitable.

Using the Cassini spacecraft, scientists discovered that Saturn’s auroras are more complex than ever imagined. By observing in radio, ultraviolet, and infrared light simultaneously, they found parts of the main aurora spin with the planet while other ‘hot spots’ lag behind, revealing a dynamic dance in Saturn’s atmosphere.

In January 2009, NASA’s Cassini spacecraft stared at Saturn’s southern pole for a full planetary rotation, about 11 hours. What it saw changed our understanding of the ringed planet’s auroras. Scientists expected to see a single, unified light show spinning in sync with Saturn’s powerful magnetic field. Instead, they saw two different dances happening at once. The main auroral oval hosted a huge, bright region that was locked in step with the planet’s rotation, a phenomenon known as corotation. But simultaneously, smaller, isolated ‘hot spots’ were also seen drifting along the oval at a slower pace. This sub-corotation matches the speed of the cold plasma trapped further out in Saturn’s magnetosphere. This was the first time both motions were clearly observed co-existing, revealing a far more complex and layered auroral system than previously thought.

Read the original research paper on arXiv

We saw a complex dance: a huge, steady waltz accompanied by smaller, slower-moving spotlights all within the same auroral ring.
— L. Lamy, Lead Researcher

Like on Earth, Saturn’s auroras are created when energetic charged particles spiral down the planet’s magnetic field lines and collide with gases in the upper atmosphere. The main auroral oval marks the boundary between magnetic field lines that close near the planet and those that stretch far out into space. The discovery of two speeds tells us about the different sources of these particles. The large, co-rotating feature is likely powered by a massive electrical current system that is rigidly tied to Saturn’s fast rotation. In contrast, the smaller, sub-corotating spots are thought to be footprints of plasma blobs moving more slowly in the middle region of the magnetosphere. As these plasma blobs drift, they rain down electrons, creating glowing spots that lag behind the planet’s spin. Seeing both at once means we’re watching two different layers of the magnetosphere interacting with the atmosphere simultaneously.

Here at NorthernLightsIceland.com, we often talk about how the Sun’s solar wind triggers Earth’s auroras. But this study revealed Saturn can create its own ‘space weather’. During the observation, Cassini witnessed a powerful substorm-like event—a massive injection of energetic ions into the inner magnetosphere. This wasn’t caused by the Sun, but by an instability in Saturn’s own stretched-out magnetic tail, likely a plasmoid ejection where a magnetic bubble of plasma is violently released. This internal explosion of energy caused the aurora to flare up dramatically on the dawn side. This shows that while the Sun has an influence, giant planets like Saturn are powerful enough to drive their own auroral activity from within. It’s a reminder that every planet’s magnetic field and atmosphere interact in unique and spectacular ways.

It’s like finding out Saturn can create its own storms, independent of the Sun. The magnetotail stores energy and then releases it in powerful bursts.
— NorthernLightsIceland.com Science Team

This groundbreaking discovery was only possible because Cassini used a whole suite of instruments at the same time. The Ultraviolet Imaging Spectrograph (UVIS) captured detailed images of the auroral shapes. The Visual and Infrared Mapping Spectrometer (VIMS) measured the temperature and energy of the aurora in infrared. The Radio and Plasma Wave Science (RPWS) instrument listened for Saturn’s natural radio emissions, known as SKR. And the Ion and Neutral Camera (INCA) detected the injection of energetic particles that fueled the storm. By combining these datasets, scientists could directly link events. They saw that a specific type of flickering radio signal, called an SKR arc, perfectly corresponded to a sub-corotating UV hot spot. It was like hearing a sound and seeing exactly what was making it, a true multi-spectral ‘aha!’ moment in planetary science.

Q: Why do parts of Saturn’s aurora move at different speeds?
A: The different speeds reflect different regions of Saturn’s magnetosphere. The fast, co-rotating part is tied to the inner magnetic field which spins rigidly with the planet. The slower, sub-corotating spots are connected to plasma further out, which can’t keep up and lags behind.

Q: What is a ‘plasmoid ejection’?
A: It’s when a planet’s magnetic tail becomes so stretched and loaded with energy that it snaps back like a rubber band. This process violently ejects a massive bubble of plasma (a plasmoid) away from the planet, while sending another burst of energy and particles rocketing back towards it, causing intense auroras.

Q: Could we see Saturn’s aurora with a telescope from Earth?
A: No, not really. Saturn’s auroras are primarily in ultraviolet and infrared wavelengths, which are blocked by Earth’s atmosphere. To see them in their full glory, we need space-based telescopes like Hubble or spacecraft in orbit around Saturn, like Cassini was.

Q: How is Saturn’s aurora different from Earth’s?
A: While both are caused by particles hitting the atmosphere, Saturn’s auroras are more influenced by its rapid rotation and internal magnetospheric processes. Earth’s auroras are much more directly and immediately controlled by the activity of the solar wind blowing from our Sun.

Scientists were thrilled by a faint radio signal from the distant planet τ Boötis b, a potential sign of a massive aurora. But when they listened again with the same powerful telescope, the planet was silent, creating a cosmic mystery.

Imagine tuning an old radio and hearing a faint, mysterious broadcast from a station you’ve never heard before. That’s what happened in 2017 when scientists using the LOFAR radio telescope found a tentative signal from the τ Boötis system, 51 light-years away. They suspected it was coming from the planet τ Boötis b, a massive ‘hot Jupiter’. This whisper from across the stars was incredibly exciting because it suggested the planet had a powerful magnetic field—a key ingredient for planetary evolution. But science demands proof. A follow-up campaign was launched in 2020 to listen again, covering more of the planet’s orbit than ever before. The telescope was aimed, the data poured in, but this time… there was only static. The signal was gone.

Read the full research paper on arXiv: “Follow-up LOFAR observations of the τ Boötis exoplanetary system”

If confirmed, this detection will be a major contribution to exoplanet science. However, follow-up observations are required to confirm this detection.
— Jake D. Turner et al., Abstract

So, what kind of signal were they looking for? It’s created by a process called the Cyclotron Maser Instability (CMI). Think of it like a natural cosmic laser. When energetic particles from the star (the stellar wind) slam into a planet’s magnetic field, they get trapped and spiral around the magnetic field lines at incredible speeds. This spiraling motion makes the electrons radiate powerful, focused beams of radio waves. It’s the same basic physics that creates auroras on Earth, but on a ‘hot Jupiter’ like τ Boötis b, this process would be thousands of times more powerful. The radio waves are beamed out like a lighthouse, and we can only detect them if that beam happens to sweep across Earth. This is why finding such a signal is both difficult and incredibly informative.

CMI radio emission is circularly polarized, beamed, and time-variable.
— Philippe Zarka et al., Introduction

On Earth, our magnetic field funnels solar particles to the poles, creating the beautiful Northern and Southern Lights. The signal from τ Boötis b would be the radio equivalent of an aurora on a colossal scale. Finding a magnetic field tells us so much about a planet. It acts as a shield, deflecting harmful stellar radiation and preventing the planet’s atmosphere from being stripped away into space. For rocky planets in the habitable zone, a magnetic field might even be essential for life. For a gas giant like τ Boötis b, it gives us clues about its deep interior, where the field is generated. While this planet is far too hot for life, understanding its magnetic environment helps us build better models for all kinds of planets, including potentially habitable ones.

A magnetic field might be one of the many properties needed on Earth-like exoplanets to sustain their habitability.
— Jean-Mathias Grießmeier et al., Introduction

How did the scientists know the silence wasn’t just a problem with their telescope? Their method was clever. For every observation, they used an ‘ON-beam’ pointed directly at τ Boötis and three simultaneous ‘OFF-beams’ aimed at empty patches of sky nearby. This allowed them to subtract any background noise or radio interference from Earth, ensuring that any real signal would have to come from the target. When they compared the ON-beam to the OFF-beams in the new data, they were identical—just cosmic static. The lack of a signal is now a puzzle. Was the first detection an error? Or is the planet’s radio broadcast variable? The star itself has a rapid 120-day magnetic cycle, which could be turning the planet’s radio show on and off. The detectives need more clues.

Our new observations do not show any signs of bursty or slow emission from the τ Boötis exoplanetary system. The cause for our non-detection is currently degenerate.
— Jake D. Turner et al., Abstract

Q: So, does the planet τ Boötis b have a magnetic field or not?
A: We still don’t know for sure. The first hint of a signal suggests it might, but the follow-up non-detection makes it an open mystery. More observations are needed to solve it.

Q: Why would the signal disappear?
A: There are a few possibilities. The first signal could have been a very rare fluke or an instrumental glitch. More likely, the planet’s radio emission is variable. The host star’s own activity changes, which could affect the ‘power’ of the planet’s aurora, making it sometimes too faint for us to detect.

Q: What is a ‘hot Jupiter’?
A: A hot Jupiter is a type of gas giant planet, similar in size to our Jupiter, but that orbits extremely close to its star. This makes them incredibly hot, with temperatures reaching thousands of degrees.

Q: Why is it important to find magnetic fields on other planets?
A: Magnetic fields act like a protective shield for a planet, deflecting harmful particles from its star. This can prevent the atmosphere from being blown away into space, which is considered a critical factor for a planet’s long-term habitability.

Scientists used one of the world’s most powerful telescopes to hunt for the glowing auroras on two distant ‘hot Jupiter’ planets. But the search came up empty, creating a cosmic mystery about these strange and stormy worlds.

Imagine a planet bigger than Jupiter, orbiting so close to its star that its year lasts only a few days. These are ‘hot Jupiters’, and scientists believe they should have spectacular auroras, far more powerful than Earth’s Northern Lights. Researchers aimed the giant Keck telescope at two of these worlds, WASP-80b and WASP-69b, hoping to catch the tell-tale infrared glow of a special molecule called H3+. This molecule is created when energetic particles from the star slam into the planet’s atmosphere, guided by a magnetic field. Finding this glow would be a huge discovery, but after hours of staring into the cosmos, the light just wasn’t there.

Read the original research paper on arXiv

On Earth, auroras happen when solar wind particles hit oxygen and nitrogen, making them glow green and red. But on gas giants like Jupiter, the atmosphere is mostly hydrogen. When charged particles funnel down the planet’s powerful magnetic field lines and crash into the hydrogen gas, they create a new, energized molecule called H3+ (pronounced ‘H-three-plus’). This molecule is unstable and quickly releases its extra energy as infrared light—light that is invisible to our eyes but can be seen by special telescopes. Scientists call H3+ the ‘thermostat’ of Jupiter’s upper atmosphere because this process is the main way the planet cools itself down. Finding this specific infrared light on an exoplanet is the best way to confirm an aurora is happening.

Auroras aren’t just pretty light shows; they are giant signposts in space. The single most important thing an aurora tells us is that a planet has a magnetic field. A magnetic field acts like a planetary shield, deflecting harmful radiation and stopping the star’s wind from blowing the atmosphere away. Finding a magnetic field on an exoplanet would be a first, and it would give us vital clues about the planet’s interior and its potential to hold onto an atmosphere over billions of years. Studying these distant auroras also helps us understand the ‘space weather’ created by the host star, giving us a window into the violent interactions between stars and their planets.

Observations of auroras on exoplanets would provide numerous insights into planet-star systems, including potential detections of the planetary magnetic fields.
— Richey-Yowell et al. (2025)

Finding a faint aurora from trillions of miles away is like trying to hear a whisper in a rock concert. The planet’s light is completely overwhelmed by its star. To find the signal, astronomers used high-resolution spectroscopy, a technique that splits the incoming light into thousands of different shades of color. Then, they used a powerful data-sifting method called cross-correlation. They created a computer model of what the H3+ aurora ‘fingerprint’ should look like, with all its dozens of individual light lines. They then compared this model to the real data, shifting it around to match the planet’s velocity as it orbited its star. If a real signal was hidden in the noise, it would pop out when it lined up perfectly with the model. But even with this clever trick, no signal appeared.

Q: Does this mean these planets have no auroras or magnetic fields?
A: Not necessarily. It just means that any auroras they have are too faint for our current telescopes to see. The magnetic fields might be weaker than expected, or something else in the atmosphere could be interfering with the aurora’s glow.

Q: Why can’t we just take a picture of the auroras like we do on Earth?
A: These planets are incredibly far away and extremely faint compared to their bright host stars. We can’t resolve them into a picture; all we receive is a single point of light that contains the combined light of the star and the planet, which we must then carefully separate using techniques like spectroscopy.

Q: What is a ‘hot Jupiter’?
A: A hot Jupiter is a type of gas giant exoplanet, similar in size to our own Jupiter, but that orbits extremely close to its star. This makes them incredibly hot, with temperatures reaching thousands of degrees, and gives them very short orbital periods (a ‘year’ can be just a few Earth days).

Q: What’s the next step in the search for alien auroras?
A: The next step is to use even more powerful observatories, like the upcoming class of Extremely Large Telescopes (ELTs). With their giant mirrors, they will be sensitive enough to either finally detect these faint auroras or confirm that they are truly absent, deepening the mystery.

Scientists studying WASP-76b — a giant planet 640 light-years away — discovered that its skies may rain molten metal. This strange world helps us understand how heat, magnetism, and space weather shape the Northern Lights on Earth.

In 2020, astronomers using the European Southern Observatory’s Very Large Telescope (VLT) observed something extraordinary on a distant exoplanet known as WASP-76b. Spectroscopic data revealed clear signatures of ionized and neutral metals, including vaporized iron, in its upper atmosphere — a discovery that sparked intense interest across the astrophysics community.

Building on that initial detection, a 2021 analysis led by Ehrenreich et al., published on arXiv as “The three-dimensional structure of the ultrahot Jupiter WASP-76 b” (arXiv:2102.01095v1), explored how the planet’s extreme temperature differences drive such exotic chemistry. Their findings suggest that the day side of WASP-76b — blasted by constant stellar radiation — reaches over 2400 °C (≈4350 °F), hot enough to vaporize metals like iron.

Intense supersonic winds then carry these metallic vapors toward the cooler night side, where the temperature drops dramatically. There, the vapor condenses into molten droplets of iron rain — a literal storm of liquid metal falling through alien skies.

“It’s like a cosmic foundry — one side acts as a furnace, the other a cooling chamber,” explains Dr. David Ehrenreich of the University of Geneva, lead author of the study.

WASP-76b is what scientists call an ultra-hot Jupiter — a gas giant similar in size to Jupiter but orbiting extremely close to its star. It’s so close, in fact, that a full “year” on the planet lasts less than two Earth days. Because of this tight orbit, WASP-76b is tidally locked, meaning one side permanently faces its star while the other remains in endless night.

This leads to staggering temperature contrasts. On the day side, conditions are so extreme that molecules break apart and metals like iron literally turn into vapor. Meanwhile, the night side is much cooler — still thousands of degrees hot, but cold enough for those metal vapors to condense back into liquid.

The study by Ehrenreich et al. (2021, arXiv:2102.01095v1) used a method called high-resolution transmission spectroscopy to map how gases move across the planet. By watching how starlight filters through different parts of the atmosphere during its orbit, researchers could trace wind speeds, temperature gradients, and chemical signatures in three dimensions.

What they found was a massive heat-driven circulation system — winds likely exceeding 5 km per second (about 18,000 km/h) transporting vaporized metals from the scorching day side to the cooler night hemisphere. Once there, the vapor condenses and falls as molten iron droplets before being re-vaporized when the winds carry it back into daylight again.

In essence, WASP-76b operates like a planet-sized metal recycling machine, continuously melting and raining iron in a dramatic loop powered by stellar radiation.

This discovery matters not just for its strangeness, but because it gives astronomers a glimpse into how extreme heat, magnetism, and atmospheric flow interact — processes that also influence space weather and auroral activity throughout the galaxy, including here on Earth.

Why does a planet hundreds of light-years away matter to Icelanders watching the Northern Lights?

Because the same forces are at work.
The way charged particles move in WASP-76b’s magnetic field mirrors how the solar wind interacts with Earth’s magnetosphere to produce auroras.

Studying these alien storms helps scientists predict how radiation and plasma behave in extreme conditions — improving models of space weather that affect satellites, GPS, and auroral activity.

The discovery relied on spectroscopy — analyzing starlight as it passes through a planet’s atmosphere.
Different elements absorb specific wavelengths, creating a chemical “fingerprint.”
By detecting these signatures, scientists can tell which gases are present — even from hundreds of light-years away.

“Spectroscopy is our interstellar thermometer and barometer,” explains Dr. Ehrenreich. “It tells us what’s happening in atmospheres we can’t physically reach.”

Future missions like the James Webb Space Telescope will look for similar signs of metallic weather — and possibly even aurora-like glows on other worlds.

Q: What is WASP-76b?
A: It’s an ultra-hot gas giant orbiting very close to its star. The extreme heat vaporizes metals like iron.

Q: Does it really rain metal there?
A: Yes — iron gas from the day side likely condenses and falls as molten droplets on the night side.

Q: What does this have to do with auroras?
A: Both involve the movement of charged particles and magnetic fields — studying one helps us understand the other.

Q: Can telescopes actually see the rain?
A: Not directly. Scientists infer it from the light signatures captured by spectrographs like ESPRESSO and HARPS.

Q: How far away is WASP-76b?
A: Roughly 640 light-years from Earth, in the constellation Pisces.