Jupiter's Violent Beauty: Juno's Most Extraordinary Discoveries

This crescent view of Jupiter, captured by Juno during one of its regular close passes in February 2022, is essentially impossible to see from Earth — our planet's position always places Jupiter near full illumination when it is visible in our sky. From Juno's vantage point moving away from the planet after perijove, Jupiter appears as a crescent with the dark side faintly illuminated by the reflection of sunlight off its moons. Even in this unfamiliar aspect, the planet's characteristic banded structure and swirling vortices are unmistakable, lit by a Sun so distant it provides only 3.7% of the light Earth receives.

On May 24, 2018, Juno's Stellar Reference Unit star camera captured this high-resolution image of Jupiter's northern auroral oval, with several small bright dots and streaks visible — the signatures of high-energy relativistic electrons, but also the first in-situ detection of Jovian lightning from close range. On Earth, lightning originates in water clouds near the equator; on Jupiter, where water is rare in the visible atmosphere, lightning likely occurs in clouds of ammonia and water deeper down, and happens most frequently near the poles rather than the equator. Juno's instruments detected up to 600 lightning bolts per day.

This infrared image from Juno's first close approach in August 2016 shows Jupiter's southern aurora for the first time from a spacecraft in polar orbit — a view essentially impossible to obtain from Earth or from previous flyby missions. The southern aurora appears as a bright, irregular oval surrounding the south pole, powered by the most intense auroral emissions in the solar system. Jupiter's auroras are generated not only by solar wind particles but also by material ejected from its volcanic moon Io, which orbits within Jupiter's magnetic field and continually injects sulphur and oxygen ions into the system.

In this view of a vortex near Jupiter's north pole captured by JunoCam in 2023, a bright flash visible in the storm system represents the glow from a bolt of Jovian lightning. The scale of the storm surrounding it is difficult to grasp without context: each of the swirling cloud structures visible here is larger than Earth's entire continental United States. Jupiter's atmosphere has no solid surface to brake its storms; the Great Red Spot has been spinning continuously for at least 350 years, and many other storm systems appear to be similarly long-lived features of the planet's circulation.

On June 29, 2016, just five days before its orbital insertion burn, Juno was 5.3 million kilometres from Jupiter when JunoCam captured this final approach image. The four largest Jovian moons — Io, Europa, Ganymede, and Callisto — are visible aligned around the planet, and the alternating light and dark bands of Jupiter's cloud layers are already clearly resolved. This was the last image taken before Juno's instruments were powered down in preparation for the risky orbital insertion that would either put the spacecraft in orbit or send it past the planet forever.

From 10.9 million kilometres, Juno captured this colour view on June 21, 2016, showing Jupiter and all four Galilean moons in a single frame. Io, Europa, Ganymede, and Callisto were discovered by Galileo Galilei in January 1610 — the first objects proven to orbit a body other than Earth, and a foundational observation for the Copernican revolution. Europa, the ice-covered moon second from Jupiter in this image, is now known to harbour a global subsurface ocean with twice as much liquid water as all of Earth's oceans combined, making it one of the most promising places in the solar system to search for extraterrestrial life.

This composite image, combining a Cassini optical view of Jupiter with layers from Juno's Microwave Radiometer, shows what different depths of Jupiter's atmosphere look like to instruments that penetrate beyond the visible cloud tops. Each microwave channel corresponds to a different pressure level and temperature regime deep inside the planet. The MWR revealed that Jupiter's famous coloured cloud bands are not shallow weather patterns but structures descending hundreds of kilometres into the atmosphere — far deeper than any previous measurement had suggested.

This illustration of Juno soaring over Jupiter's south pole captures the orientation of the spacecraft during each perijove pass — instruments facing down into the cloud tops while the solar panels track the distant Sun. Juno is the first solar-powered spacecraft to operate at Jupiter's distance; its four wing-like solar panels, each 2.7 by 8.9 metres, must operate with sunlight 25 times weaker than at Earth's distance. The spacecraft's design prioritises instruments over fuel, carrying a particularly powerful magnetometer suite and microwave sounder that have transformed our understanding of Jupiter's interior structure.

Jupiter's alternating light zones and dark belts are visible here in a Juno close flyby image showing their fine structure — the individual vortices, waves, and cyclone clusters that give each band its characteristic texture. Zone regions are higher in altitude, cooler, and appear white or cream from the ammonia ice crystals at their tops; belt regions are lower, warmer, and appear dark brown or reddish from the chemical compounds exposed by the downwelling circulation. Juno has shown that this banding persists to far greater depths than previously believed, suggesting that even Jupiter's deep interior rotates in a banded pattern.

This crescent view of Jupiter, captured by Juno during one of its regular close passes in February 2022, is essentially impossible to see from Earth — our planet's position always places Jupiter near full illumination when it is visible in our sky. From Juno's vantage point moving away from the planet after perijove, Jupiter appears as a crescent with the dark side faintly illuminated by the reflection of sunlight off its moons. Even in this unfamiliar aspect, the planet's characteristic banded structure and swirling vortices are unmistakable, lit by a Sun so distant it provides only 3.7% of the light Earth receives.

On May 24, 2018, Juno's Stellar Reference Unit star camera captured this high-resolution image of Jupiter's northern auroral oval, with several small bright dots and streaks visible — the signatures of high-energy relativistic electrons, but also the first in-situ detection of Jovian lightning from close range. On Earth, lightning originates in water clouds near the equator; on Jupiter, where water is rare in the visible atmosphere, lightning likely occurs in clouds of ammonia and water deeper down, and happens most frequently near the poles rather than the equator. Juno's instruments detected up to 600 lightning bolts per day.

This infrared image from Juno's first close approach in August 2016 shows Jupiter's southern aurora for the first time from a spacecraft in polar orbit — a view essentially impossible to obtain from Earth or from previous flyby missions. The southern aurora appears as a bright, irregular oval surrounding the south pole, powered by the most intense auroral emissions in the solar system. Jupiter's auroras are generated not only by solar wind particles but also by material ejected from its volcanic moon Io, which orbits within Jupiter's magnetic field and continually injects sulphur and oxygen ions into the system.

In this view of a vortex near Jupiter's north pole captured by JunoCam in 2023, a bright flash visible in the storm system represents the glow from a bolt of Jovian lightning. The scale of the storm surrounding it is difficult to grasp without context: each of the swirling cloud structures visible here is larger than Earth's entire continental United States. Jupiter's atmosphere has no solid surface to brake its storms; the Great Red Spot has been spinning continuously for at least 350 years, and many other storm systems appear to be similarly long-lived features of the planet's circulation.

On June 29, 2016, just five days before its orbital insertion burn, Juno was 5.3 million kilometres from Jupiter when JunoCam captured this final approach image. The four largest Jovian moons — Io, Europa, Ganymede, and Callisto — are visible aligned around the planet, and the alternating light and dark bands of Jupiter's cloud layers are already clearly resolved. This was the last image taken before Juno's instruments were powered down in preparation for the risky orbital insertion that would either put the spacecraft in orbit or send it past the planet forever.

From 10.9 million kilometres, Juno captured this colour view on June 21, 2016, showing Jupiter and all four Galilean moons in a single frame. Io, Europa, Ganymede, and Callisto were discovered by Galileo Galilei in January 1610 — the first objects proven to orbit a body other than Earth, and a foundational observation for the Copernican revolution. Europa, the ice-covered moon second from Jupiter in this image, is now known to harbour a global subsurface ocean with twice as much liquid water as all of Earth's oceans combined, making it one of the most promising places in the solar system to search for extraterrestrial life.

This composite image, combining a Cassini optical view of Jupiter with layers from Juno's Microwave Radiometer, shows what different depths of Jupiter's atmosphere look like to instruments that penetrate beyond the visible cloud tops. Each microwave channel corresponds to a different pressure level and temperature regime deep inside the planet. The MWR revealed that Jupiter's famous coloured cloud bands are not shallow weather patterns but structures descending hundreds of kilometres into the atmosphere — far deeper than any previous measurement had suggested.

This illustration of Juno soaring over Jupiter's south pole captures the orientation of the spacecraft during each perijove pass — instruments facing down into the cloud tops while the solar panels track the distant Sun. Juno is the first solar-powered spacecraft to operate at Jupiter's distance; its four wing-like solar panels, each 2.7 by 8.9 metres, must operate with sunlight 25 times weaker than at Earth's distance. The spacecraft's design prioritises instruments over fuel, carrying a particularly powerful magnetometer suite and microwave sounder that have transformed our understanding of Jupiter's interior structure.

Jupiter's alternating light zones and dark belts are visible here in a Juno close flyby image showing their fine structure — the individual vortices, waves, and cyclone clusters that give each band its characteristic texture. Zone regions are higher in altitude, cooler, and appear white or cream from the ammonia ice crystals at their tops; belt regions are lower, warmer, and appear dark brown or reddish from the chemical compounds exposed by the downwelling circulation. Juno has shown that this banding persists to far greater depths than previously believed, suggesting that even Jupiter's deep interior rotates in a banded pattern.