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Hubble’s new observations of Jupiter’s Great Red Spot, collected over 90 days between December 2023 to March 2024

Astronomers have observed Jupiter’s legendary Great Red Spot (GRS), an anticyclone large enough to swallow Earth, for at least 150 years. But there are always new surprises – especially when the NASA/ESA Hubble Space Telescope takes a close-up look at it.

Eight Hubble images showing Jupiter’s Great Red Spot. The GRS appears as a bright red oval in the middle of cream-coloured cloud bands. The images trace changes in the GRS’s size, shape, brightness, colour, and twisting, over a period of 90 days between December 2023 and March 2024.
Using Hubble Space Telescope data spanning approximately 90 days (between December 2023 and March 2024) when the giant planet Jupiter was approximately 740 million kilometres from the Sun, astronomers measured the Great Red Spot’s size, shape, brightness, colour, and vorticity over one full oscillation cycle. The data reveal that the Great Red Spot is not as stable as it might look. It was observed going through an oscillation in its elliptical shape, jiggling like a bowl of gelatin. The cause of the 90-day oscillation is unknown.
Credit: NASA, ESA, A. Simon (GSFC)

Hubble’s new observations of the famous red storm, collected over 90 days between December 2023 to March 2024, reveal that the GRS is not as stable as it might look. The recent data show the GRS jiggling like a bowl of gelatin. The combined Hubble images allowed astronomers to assemble a time-lapse movie of the squiggly behaviour of the GRS.

“While we knew its motion varies slightly in its longitude, we didn’t expect to see the size oscillate. As far as we know, it’s not been identified before,” said Amy Simon of NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “This is really the first time we’ve had the proper imaging cadence of the GRS. With Hubble’s high resolution we can say that the GRS is definitively squeezing in and out at the same time as it moves faster and slower. That was very unexpected, and at present there are no hydrodynamic explanations.”

Hubble monitors Jupiter and the other outer solar system planets every year through the Outer Planet Atmospheres Legacy program (OPAL) led by Simon, but these observations were from a program dedicated to the GRS. Understanding the mechanisms of the largest storms in the solar system puts the theory of hurricanes on Earth into a broader cosmic context, which might be applied to better understanding the meteorology on planets around other stars.

Eight images of the giant planet Jupiter spanning approximately 90 days between December 2023 and March 2024. The planet appears striped, with brown and white horizontal bands of clouds. These stripes are called belts (sinking air) and bands (rising air). The polar regions appear more mottled.
Using Hubble Space Telescope data spanning approximately 90 days (between December 2023 and March 2024) when the giant planet Jupiter was approximately 740 million kilometres from the Sun, astronomers measured the Great Red Spot’s size, shape, brightness, colour, and vorticity over a full oscillation cycle. The data reveal that the Great Red Spot is not as stable as it might look. It was observed going through an oscillation in its elliptical shape, jiggling like a bowl of gelatin. The cause of the 90-day oscillation is unknown. The observation is part of the Outer Planet Atmospheres Legacy program (OPAL).
Credit: NASA, ESA, A. Simon (GSFC)

Simon’s team used Hubble to zoom in on the GRS for a detailed look at its size, shape, and any subtle colour changes.

“When we look closely, we see a lot of things are changing from day to day,” said Simon.

This includes ultraviolet-light observations showing that the distinct core of the storm gets brightest when the GRS is at its largest size in its oscillation cycle. This indicates less haze absorption in the upper atmosphere.

“As it accelerates and decelerates, the GRS is pushing against the windy jet streams to the north and south of it,” said co-investigator Mike Wong of the University of California at Berkeley. “It’s similar to a sandwich where the slices of bread are forced to bulge out when there’s too much filling in the middle.” 

Wong contrasted this to Neptune, where dark spots can drift wildly in latitude without strong jet streams to hold them in place. Jupiter’s Great Red Spot has been held at a southern latitude, trapped between the jet streams, for the extent of Earth-bound telescopic observations.

The team has continued watching the GRS shrink since the OPAL program began 10 years ago. They predict it will keep shrinking before taking on a stable, less-elongated, shape. 

“Right now it’s over-filling its latitude band relative to the wind field. Once it shrinks inside that band the winds will really be holding it in place,” said Simon.

The team predicts that the GRS will probably stabilise in size, but for now Hubble only observed it for one oscillation cycle.

“This is a great example of the power of Hubble’s exquisite imaging for monitoring of the atmospheres of the outer planets,” said co-investigator Patrick Irwin of the University of Oxford. “With these new observations we were able to study the dynamics and evolution of the GRS over three months, building on our understanding of the long-term properties of Jupiter obtained from the OPAL program over the past decade.”

The researchers hope that in the future other high-resolution images from Hubble might identify other Jovian parameters that indicate the underlying cause of the oscillation.

 

Press release from ESA Hubble

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 #1373ERS 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

Hubble tracks the stormy weather on Jupiter

 

The giant planet Jupiter, in all its banded glory, is revisited by the NASA/ESA Hubble Space Telescope in these latest images, taken on 5–6 January 2024, that capture both sides of the planet. Hubble monitors Jupiter and the other outer Solar System planets every year under the Outer Planet Atmospheres Legacy programme (OPAL). This is because these large worlds are shrouded in clouds and hazes stirred up by violent winds, leading to a kaleidoscope of ever-changing weather patterns.

The largest and nearest of the giant outer planets, Jupiter’s colourful clouds present an ever-changing kaleidoscope of shapes and colours. This is a planet where there is always stormy weather: cyclones, anticyclones, wind shear, and the largest storm in the Solar System, the Great Red Spot. Jupiter has no solid surface and is perpetually covered with largely ammonia ice-crystal clouds that are only about 48 kilometres thick in an atmosphere that’s tens of thousands of kilometres deep and give the planet its banded appearance. The bands are produced by air flowing in different directions at various latitudes with speeds approaching 560 kilometres per hour. Lighter-hued areas where the atmosphere rises are called zones. Darker regions where air falls are called belts. When these opposing flows interact, storms and turbulence appear. Hubble tracks these dynamic changes every year with unprecedented clarity, and there are always surprises. The many large storms and small white clouds seen in Hubble’s latest images are evidence for a lot of activity going on in Jupiter’s atmosphere right now.

 

 

Press release from ESA Hubble.

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.

Hubble monitors changing weather and seasons on Jupiter and Uranus
Hubble monitors changing weather and seasons on Jupiter and Uranus. Note: The planets do not appear in this image to scale. Credit:
NASA, ESA, STScI, A. Simon (NASA-GSFC), M. H. Wong (UC Berkeley), J. DePasquale (STScI)

 

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.

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

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].

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.

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

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.

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 1679013937 , and 16995 (A. Simon).

 

 

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