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Astronomy

Webb reveals new details in Jupiter’s aurora

By ScientifiCult 12 May 2025

Webb reveals new details in Jupiter’s aurora

The NASA/ESA/CSA James Webb Space Telescope has captured new details of the auroras on our Solar System’s largest planet. The dancing lights observed on Jupiter are hundreds of times brighter than those seen on Earth. With Webb’s advanced sensitivity, astronomers have studied the phenomena to better understand Jupiter’s magnetosphere.

Three panels, each showing a close-up near-infrared image of Jupiter’s north pole, in shades of orange. The planet is mostly dark. Thick, bright arcs and rings caused by aurorae cover the pole. The centre and right panels each show the aurora a few minutes later in time, as Webb’s field of view slowly scans over the planet. — The NASA/ESA/CSA James Webb Space Telescope has captured new details of the auroras on our Solar System’s largest planet. The dancing lights observed on Jupiter are hundreds of times brighter than those seen on Earth.
These observations of Jupiter’s auroras were captured with Webb’s Near-InfraRed Camera (NIRCam) on 25 December 2023 (F335M filter). Scientists found that the emission from the trihydrogen ion, known as H3+, is far more variable than previously believed. H3+ is created by the impact of high energy electrons on molecular hydrogen. Because this emission shines brightly in the infrared, Webb’s instruments are well equipped to observe it.
Credit: ESA/Webb, NASA, CSA, J. Nichols (University of Leicester), M. Zamani (ESA/Webb)

The auroras are created when high-energy particles enter a planet’s atmosphere near its magnetic poles and collide with atoms of gas. Not only are the auroras on Jupiter huge in size, they are also hundreds of times more energetic than auroras on Earth. Here, auroras are caused by solar storms — when charged particles rain down on the upper atmosphere, excite gases and cause them to glow colours of red, green and purple. Meanwhile, Jupiter has an additional source for its auroras; the strong magnetic field of the gas giant grabs charged particles from its surroundings. This includes not only the charged particles within the solar wind but also the particles thrown into space by its orbiting moon Io, known for its numerous and large volcanoes. Io’s volcanoes spew particles that, remarkably, escape the moon’s gravity and orbit Jupiter. A barrage of charged particles unleashed by the sun during solar storms also reaches the planet. Jupiter’s large and powerful magnetic field captures charged particles and accelerates them to tremendous speeds. These speedy particles slam into the planet’s atmosphere at high energies, which excites the gas and causes it to glow.

Now, Webb’s unique capabilities are providing new insights into the auroras on Jupiter. The telescope’s sensitivity allows astronomers to increase the shutter speed in order to capture fast-varying auroral features. New data was captured with Webb’s Near-InfraRed Camera (NIRCam) on Christmas Day 2023 by a team of scientists led by Jonathan Nichols from the University of Leicester in the United Kingdom.

“What a Christmas present it was – it just blew me away!” shared Nichols. “We wanted to see how quickly the auroras change, expecting it to fade in and out ponderously, perhaps over a quarter of an hour or so. Instead we observed the whole auroral region fizzing and popping with light, sometimes varying by the second.”

On the right is the planet Jupiter as seen in near-infrared light. Its clouds are dark blue and white in colour, with some red spots within the clouds, while its poles are tinged with green, yellow and red. A box over the north pole is overlain with more data in shades of orange, displaying aurorae as arcs and rings on the planet. To left, this area is shown larger in size and captioned “09:53:57 25 Dec. 2023”. — The NASA/ESA/CSA James Webb Space Telescope has captured new details of the auroras on our Solar System’s largest planet. The dancing lights observed on Jupiter are hundreds of times brighter than those seen on Earth.
These observations of Jupiter’s auroras (shown on the left of the above image) were captured with Webb’s Near-InfraRed Camera (NIRCam) on 25 December 2023 (F335M filter). Scientists found that the emission from the trihydrogen ion, known as H3+, is far more variable than previously believed. H3+ is created by the impact of high energy electrons on molecular hydrogen. Because this emission shines brightly in the infrared, Webb’s instruments are well equipped to observe it. The image on the right shows the planet Jupiter to indicate the location of the observed auroras, which was originally published in 2023 (F164N, F212N, and F360M filters).
Credit: NASA, ESA, CSA, STScI, Ricardo Hueso (UPV), Imke de Pater (UC Berkeley), Thierry Fouchet (Observatory of Paris), Leigh Fletcher (University of Leicester), Michael H. Wong (UC Berkeley), Joseph DePasquale (STScI), J. Nichols (University of Leicester), M. Zamani (ESA/Webb)

The team’s data found that the emission from the trihydrogen ion, known as H3+, is far more variable than previously believed. The observations will help develop scientists’ understanding of how Jupiter’s upper atmosphere is heated and cooled.

The team also uncovered some unexplained observations in their data.

“What made these observations even more special is that we also took pictures simultaneously in the ultraviolet with the NASA/ESA Hubble Space Telescope,” added Nichols. “Bizarrely, the brightest light observed by Webb had no real counterpart in Hubble’s pictures. This has left us scratching our heads. In order to cause the combination of brightness seen by both Webb and Hubble, we need to have an apparently impossible combination of high quantities of very low energy particles hitting the atmosphere – like a tempest of drizzle! We still don’t understand how this happens.”

The team now plans to study this discrepancy between the Hubble and Webb data and to explore the wider implications for Jupiter’s atmosphere and space environment. They also intend to follow up this research with more Webb observations, which they can compare with data from NASA’s Juno spacecraft to better explore the cause of the enigmatic bright emission. These insights may also support the European Space Agency’s Jupiter Icy Moons Explorer, Juice, which is en route to Jupiter to make detailed observations of the giant gas planet and its three large ocean-bearing moons – Ganymede, Callisto and Europa. Juice will take a look at Jupiter’s auroras with seven unique scientific instruments, including two imagers. These close-up measurements will help us understand how the planet’s magnetic field and atmosphere interact, as well as the effect that charged particles from Io and the other moons have on Jupiter’s atmosphere.

These results were obtained from data using Webb’s Cycle 2 observing programme #4566 and Hubble’s observing programme #17471. The results were published today in Nature Communications.

Press release from ESA Webb.

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Astronomy

Astronomers find surprising shapes in Jupiter’s upper atmosphere, above the Great Red Spot

By ScientifiCult 25 June 2024

Astronomers find surprising shapes in Jupiter’s upper atmosphere, above the Great Red Spot

Using the NASA/ESA/CSA James Webb Space Telescope, scientists observed the region above Jupiter’s iconic Great Red Spot to discover a variety of previously unseen features. The region, previously believed to be unremarkable in nature, hosts a variety of intricate structures and activity.

A image of a small area of Jupiter’s atmosphere, shaped like a jagged rectangle. The image is fuzzy and ranges from red to blue in colours, where bluer colours show lower altitudes in Jupiter’s atmosphere, and redder colours show higher altitudes. The image is centred on the Great Red Spot, which stands out as a blue circle. — New observations of the Great Red Spot on Jupiter have revealed that the planet’s atmosphere above and around the infamous storm is surprisingly interesting and active. This image shows the region observed by Webb’s Near-InfraRed Spectrograph (NIRSpec). It is stitched together from six NIRSpec Integral Field Unit images taken in July 2022, each around 300 square kilometres.
The NIRSpec observations show infrared light emitted by hydrogen molecules in Jupiter’s ionosphere. These molecules lie over 300 kilometres above the clouds of the storm, where light from the Sun ionises the hydrogen and stimulates this infrared emission. In this image, redder colours display the hydrogen emission from these high altitudes in the planet’s ionosphere. Bluer colours show infrared light from lower altitudes, including cloud-tops in the atmosphere and the very prominent Great Red Spot.
Jupiter is distant from the Sun and therefore receives a uniform, low level of daylight, meaning that most of the planet’s surface is relatively dim at these infrared wavelengths — especially compared to the emission from molecules near the poles, where Jupiter’s magnetic field is especially strong. Contrary to the researchers’ expectations that this area would therefore look homogeneous in nature, it hosts a variety of intricate structures, including dark arcs and bright spots, across the entire field of view.
Credit: Credit: ESA/Webb, NASA & CSA, H. Melin, M. Zamani (ESA/Webb)

Jupiter is one of the brightest objects in the night sky, and it is easily seen on a clear night. Aside from the bright northern and southern lights at the planet’s polar regions, the glow from Jupiter’s upper atmosphere is weak and is therefore challenging for ground-based telescopes to discern details in this region. However, Webb’s infrared sensitivity allows scientists to study Jupiter’s upper atmosphere above the infamous Great Red Spot with unprecedented detail.

The upper atmosphere of Jupiter is the interface between the planet’s magnetic field and the underlying atmosphere. Here, the bright and vibrant displays of northern and southern lights can be seen, which are fuelled by the volcanic material ejected from Jupiter’s moon Io. However, closer to the equator, the structure of the planet’s upper atmosphere is influenced by incoming sunlight. Because Jupiter receives only 4% of the sunlight that is received on Earth, astronomers predicted this region to be homogeneous in nature.

A graphic with two panels. The left side is an infrared image of the planet Jupiter, labelled “Webb/NIRCam”. The planet is shown in multiple colours, especially at the poles, and on the Great Red Spot, visible as a circular storm at the planet’s bottom-right. The Spot is surrounded by a jagged rectangle highlight. The right side shows a close-in image of that area in different colours, labelled “Webb/NIRSpec”. A coloured bar shows that bluer colours on this side show lower altitudes in Jupiter’s atmosphere, and redder colours show higher altitudes. — New observations of the Great Red Spot on Jupiter have revealed that the planet’s atmosphere above and around the infamous storm is surprisingly interesting and active. This graphic shows the region observed by Webb — first its location on a NIRCam image of the whole planet (left), and the region itself (right), imaged by Webb’s Near-InfraRed Spectrograph (NIRSpec).
The NIRSpec image is stitched together from six NIRSpec Integral Field Unit images taken in July 2022, each around 300 square kilometres, and shows infrared light emitted by hydrogen molecules in Jupiter’s ionosphere. These molecules lie over 300 kilometres above the clouds of the storm, where light from the Sun ionises the hydrogen and stimulates this infrared emission. In this image, redder colours display the hydrogen emission from these high altitudes in the planet’s ionosphere. Bluer colours show infrared light from lower altitudes, including cloud-tops in the atmosphere and the very prominent Great Red Spot.
Jupiter is distant from the Sun and therefore receives a uniform, low level of daylight, meaning that most of the planet’s surface is relatively dim at these infrared wavelengths — especially compared to the emission from molecules near the poles, where Jupiter’s magnetic field is especially strong. Contrary to the researchers’ expectations that this area would therefore look homogeneous in nature, it hosts a variety of intricate structures, including dark arcs and bright spots, across the entire field of view.
Credit: ESA/Webb, NASA & CSA, Jupiter ERS Team, J. Schmidt, H. Melin, M. Zamani (ESA/Webb)

The Great Red Spot of Jupiter was observed by Webb’s Near-InfraRed Spectrograph (NIRSpec) in July 2022, using the instrument’s Integral Field Unit capabilities. The team’s Early Release Science observations sought to investigate if this region was in fact dull, and the region above the iconic Great Red Spot was targeted for Webb’s observations. The team was surprised to discover that the upper atmosphere hosts a variety of intricate structures, including dark arcs and bright spots, across the entire field of view.

“We thought this region, perhaps naively, would be really boring,” shared team leader Henrik Melin of the University of Leicester in the United Kingdom. “It is in fact just as interesting as the northern lights, if not more so. Jupiter never ceases to surprise.”

Although the light emitted from this region is driven by sunlight, the team suggests there must be another mechanism altering the shape and structure of the upper atmosphere.

“One way in which you can change this structure is by gravity waves – similar to waves crashing on a beach, creating ripples in the sand,” explained Melin. “These waves are generated deep in the turbulent lower atmosphere, all around the Great Red Spot, and they can travel up in altitude, changing the structure and emissions of the upper atmosphere.”

The team explains that these atmospheric waves can be observed on Earth on occasion, however they are much weaker than those observed on Jupiter by Webb. They also hope to conduct follow-up Webb observations of these intricate wave patterns in the future to investigate how the patterns move within the planet’s upper atmosphere and to develop our understanding of the energy budget of this region and how the features change over time.

These findings may also support ESA’s Jupiter Icy Moons Explorer, Juice, which was launched on 14 April 2023. Juice will make detailed observations of Jupiter and its three large ocean-bearing moons — Ganymede, Callisto and Europa — with a suite of remote sensing, geophysical and in situ instruments. The mission will characterise these moons as both planetary objects and possible habitats, explore Jupiter’s complex environment in depth, and study the wider Jupiter system as an archetype for gas giants across the Universe.

These observations were taken as part of the Early Release Science programme #1373: ERS Observations of the Jovian System as a Demonstration of JWST’s Capabilities for Solar System Science (Co-PIs: I. de Pater, T. Fouchet).

“This ERS proposal was written back in 2017,” shared team member Imke de Pater of the University of California, Berkeley. “One of our objectives had been to investigate why the temperature above the Great Red Spot appeared to be high, as at the time recent observations with the NASA Infrared Telescope Facility had revealed. However, our new data showed very different results.”

These results have been published in Nature Astronomy.

Press release from ESA Webb

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Astronomy

Hubble monitors changing weather and seasons on Jupiter and Uranus

By ScientifiCult 23 March 2023

Hubble monitors changing weather and seasons on Jupiter and Uranus

Ever since its launch in 1990, the NASA/ESA Hubble Space Telescope has been an interplanetary weather observer, keeping an eye on the ever-changing atmospheres of the largely gaseous outer planets. And it’s an unblinking eye that allows Hubble’s sharpness and sensitivity to monitor a kaleidoscope of complex activities over time. Today new images are shared of Jupiter and Uranus.

The outer planets beyond Mars do not have solid surfaces to affect weather as on Earth. And sunlight is much less able to drive atmospheric circulation. Nevertheless, these are ever-changing worlds. And Hubble – in its role as interplanetary meteorologist – is keeping track, as it does every year. Jupiter’s weather is driven from the inside out, as more heat percolates up from its interior than it receives from the Sun. This heat indirectly drives colour-change cycles in the clouds, like the cycle that’s currently highlighting a system of alternating cyclones and anticyclones. Uranus has seasons that pass by at a snail’s pace because it takes 84 years to complete one orbit about the Sun. But those seasons are extreme, because Uranus is tipped on its side. As summer approaches in the northern hemisphere, Hubble sees a growing polar cap of high-altitude photochemical haze that looks similar to the smog over cities on Earth.

Inaugurated in 2014, the Hubble Space Telescope’s Outer Planet Atmospheres Legacy (OPAL) programme has been providing us with yearly views of the giant planets. Here are some recent images.

Jupiter

Credit:
NASA, ESA, STScI, A. Simon (NASA-GSFC), M. H. Wong (UC Berkeley), J. DePasquale (STScI)

The forecast for Jupiter is for stormy weather at low northern latitudes. A prominent string of alternating storms is visible, forming a ‘vortex street’ as some planetary astronomers call it. This is a wave pattern of nested cyclones and anticyclones, locked together like the alternating gears of a machine moving clockwise and counterclockwise. If the storms get close enough to each other and merge together, they could build an even larger storm, potentially rivalling the current size of the Great Red Spot. The staggered pattern of cyclones and anticyclones prevents individual storms from merging. Activity is also seen interior to these storms; in the 1990s Hubble didn’t see any cyclones or anticyclones with built-in thunderstorms, but these storms have sprung up in the last decade. Strong colour differences indicate that Hubble is seeing different cloud heights and depths as well.

The orange moon Io photobombs this view of Jupiter’s multicoloured cloud tops, casting a shadow toward the planet’s western limb. Hubble’s resolution is so sharp that it can see Io’s mottled-orange appearance, the result of its numerous active volcanoes. These volcanoes were first discovered when the Voyager 1 spacecraft flew by in 1979. The moon’s molten interior is overlaid by a thin crust through which the volcanoes eject material. Sulphur takes on various hues at different temperatures, which is why Io’s surface is so colourful. This image was taken on 12 November 2022.

Jupiter’s legendary Great Red Spot takes centre stage in this view. Though this vortex is big enough to swallow Earth, it has actually shrunk to the smallest size it has ever been according to observation records dating back 150 years. Jupiter’s icy moon Ganymede can be seen transiting the giant planet at lower right. Slightly larger than the planet Mercury, Ganymede is the largest moon in the Solar System. It is a cratered world and has a mainly water-ice surface with apparent glacial flows driven by internal heat. This image was taken on 6 January 2023.

Jupiter and its large ocean-bearing moons (Ganymede, Callisto and Europa) are the target of ESA’s Jupiter Icy Moons Explorer (Juice). Preparations are currently underway to ready Juice for liftoff from Europe’s Spaceport in French Guiana on 13 April 2023 [1].

Jupiter (November 2022 and January 2023). Credit:NASA, ESA, STScI, A. Simon (NASA-GSFC), M. H. Wong (UC Berkeley), J. DePasquale (STScI)

Uranus

Planetary oddball Uranus rolls around the Sun on its side as it follows its 84-year orbit, rather than spinning in a more ’vertical’ position as Earth does. Its weirdly tilted ‘horizontal’ rotation axis is angled just eight degrees off the plane of the planet’s orbit. One recent theory proposes that Uranus once had a massive moon that gravitationally destabilised it and then crashed into it. Other possibilities include giant impacts during the formation of the planets, or even giant planets exerting resonant torques on each other over time. The consequences of Uranus’s tilt are that for stretches of time lasting up to 42 years, parts of one hemisphere are completely without sunlight. When the Voyager 2 spacecraft visited during the 1980s, the planet’s south pole was pointed almost directly at the Sun. Hubble’s latest view shows the northern pole now tipping toward the Sun.

This is a Hubble view of Uranus taken in 2014, seven years after the northern spring equinox when the Sun was shining directly over the planet’s equator, and shows one of the first images from the OPAL programme. Multiple storms with methane ice-crystal clouds appear at mid-northern latitudes above the planet’s cyan-tinted lower atmosphere. Hubble imaged the ring system edge-on in 2007, but the rings are seen starting to open up seven years later in this view. At this time, the planet had multiple small storms and even some faint cloud bands.

As seen in 2022, Uranus’s north pole shows a thickened photochemical haze that looks similar to the smog over cities. Several little storms can be seen near the edge of the polar haze boundary. Hubble has been tracking the size and brightness of the north polar cap and it continues to get brighter year after year. Astronomers are disentangling multiple effects – from atmospheric circulation, particle properties, and chemical processes — that control how the atmospheric polar cap changes with the seasons. At the Uranian equinox in 2007, neither pole was particularly bright. As the northern summer solstice approaches in 2028 the cap may grow brighter still, and will be aimed directly toward Earth, allowing good views of the rings and the north pole; the ring system will then appear face-on. This image was taken on 10 November 2022.

Uranus (November 2014 and November 2022). Credit: NASA, ESA, STScI, A. Simon (NASA-GSFC), M. H. Wong (UC Berkeley), J. DePasquale (STScI)

Uranus (November 2014 and November 2022) compass image. Credit: NASA, ESA, STScI, A. Simon (NASA-GSFC), M. H. Wong (UC Berkeley), J. DePasquale (STScI)

Notes

[1] Ganymede is the main target of ESA’s Jupiter Icy Moons Explorer (Juice). As humanity’s next bold mission to the outer Solar System, Juice will complete numerous flybys around Ganymede, and eventually enter orbit around the moon. The mission will explore various key topics: Ganymede’s mysterious magnetic field, its hidden ocean, its complex core, its ice content and shell, its interactions with its local environment and that of Jupiter, its past and present activity, and whether or not the moon could be a habitable environment.

More information

The Hubble Space Telescope is a project of international cooperation between ESA and NASA.

The HST observations featured in this release include those from program 16790, 13937 , and 16995 (A. Simon).

Press release from ESA Hubble about the telescope observing the changing weather and seasons on Jupiter and Uranus.

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