Juno's latest discoveries shed light on Jupiter's harsh atmosphere and the fiery volcanic world of Io. The probe detected warm lava flows beneath Io's crust and revealed how heat flows across its surface like a cosmic radiator. Meanwhile, Juno's radio signals are revealing eerie new details about the temperatures at Jupiter's poles, while long-term tracking of massive cyclones around the poles shows they drift and collide with each other in bizarre ways.
The JunoCam, the visible light imager onboard NASA's Juno spacecraft, captured this enhanced-color image of Jupiter's northern high latitudes from an altitude of approximately 58,000 kilometers above Jupiter's cloud tops during Juno's 69th flyby of Jupiter on January 28, 2025. NASA/JPL-Caltech/SwRI/MSSS, image processing: Jackie Branc (CC BY)
NASA's Juno spacecraft has revealed stunning new details about Jupiter and its volcanic moon Io. By looking beneath Jupiter's dense clouds and deep within Io's surface, scientists have built a more detailed model of the fast-moving jet streams that circle Jupiter's north pole. At the same time, they also achieved a groundbreaking result: mapping the subsurface temperature of Io, revealing important clues about its internal structure and ongoing volcanic activity.
The findings were presented at a press conference at the European Geosciences Union Congress in Vienna on April 29.
"Everything about Jupiter is extreme. The planet has giant polar cyclones larger than Australia, violent jet streams, the most volcanic bodies in the solar system, the most intense aurora and the most intense radiation belts," said Scott Bolton, Juno principal investigator at Southwest Research Institute in San Antonio. "As Juno's orbit takes us into new regions of Jupiter's complex system, we will be able to get a closer look at the vast energy contained in this gas giant."
This animation was produced using data from the JIRAM instrument on NASA's Juno probe and shows the conditions in the south polar region of Io when it flies by on December 27, 2024. The bright spots are areas of increased temperature due to volcanic activity; the gray areas are formed after Io moves out of view. Image source: NASA/JPL/SwRI/ASI – JIRAM team (morning)
While Juno's Microwave Radiometer (MWR) is designed to study Jupiter's deep atmosphere, the mission team also targeted it at Io and combined it with data from the Jupiter Infrared Auroral Mapper (JIRAM) to get a more complete look at the moon's fiery interior.
"The Juno science team likes to combine differentiated data from different instruments and see what they can discover," said Juno scientist Shannon Brown of NASA's Jet Propulsion Laboratory in Southern California. "When we combined the MWR data with JIRAM's infrared images, we were surprised by what we saw: evidence of warm magma that had not yet solidified beneath Io's cooling crust. At every latitude and longitude, there were cooling lava flows."
This composite image, based on data collected in 2017 by the JIRAM instrument aboard NASA's Juno spacecraft, shows the central cyclone at Jupiter's north pole and eight cyclones surrounding it. Data from the mission suggest these storms are persistent features. Image source: NASA/JPL-Caltech/SwRI/ASI/INAF/JIRAM
Data show that about 10% of the lunar surface has slowly cooling lava remaining beneath the surface. The results may provide insight into how the moon's surface is renewed so quickly and how heat is transferred from its deep interior to the surface.
"Io's volcanoes, lava fields and underground lava flows act like a car radiator, effectively transferring heat from the interior to the surface where it cools down in the vacuum of space," Brown said.
Looking at the JIRAM data alone, the team also found that the most powerful eruption in Io's history - first detected by an infrared imager during Juno's flyby of Io on December 27, 2024 - was still spewing lava and ash as late as March 2. Juno mission scientists believe it is still active today and more observations are expected on May 6, when the solar-powered spacecraft will fly by Io at about 55,300 miles (89,000 kilometers) from the blazing moon.
This illustration depicts NASA's Juno spacecraft flying over Jupiter's south pole. Image source: NASA/JPL-Caltech
On its 53rd orbital flight (February 18, 2023), Juno began conducting radio occultation experiments to explore the atmospheric temperature structure of the gas giant planet. Using this technology, radio signals are transmitted from Earth to Juno and back again, passing through Jupiter's atmosphere on both legs of the journey. Because a planet's atmosphere bends radio waves, scientists can precisely measure the effects of this refraction to obtain detailed information about the atmosphere's temperature and density.
So far, "Juno" has completed 26 radio occultation detections. Among the most striking findings: the first-ever temperature measurement of Jupiter's north polar stratospheric cap, showing that the region is about 11 degrees Celsius cooler than its surroundings and is home to winds exceeding 100 mph (161 km/h).
The team's recent research has also focused on the cyclones plaguing Jupiter's north. Years of data collected by the JunoCam Visible Imager and JIRAM have allowed Juno scientists to observe the long-term motion of Jupiter's giant north polar cyclone and the eight surrounding cyclones. Unlike hurricanes on Earth, which usually occur in isolation at low latitudes, Jupiter's hurricanes are restricted to the polar regions.
By tracking the cyclone's motion across multiple orbits, the scientists observed that each storm gradually drifted poleward due to a process called "beta drift," in which the Coriolis force interacts with the cyclone's circular wind pattern. This is similar to how hurricanes migrate on Earth, but Earth's cyclones break up before reaching the poles due to a lack of warm, moist air to power them and a weakening of the Coriolis force near the poles. Additionally, Jupiter's cyclones clump together as they approach the poles, and their motion slows down as they begin to interact with neighboring cyclones.
"These competing forces cause the cyclones to 'bounce' against each other, like springs in a mechanical system," said Juno co-investigator Yohai Kaspi from the Weizmann Institute of Science in Israel. "This interaction not only stabilizes the entire structure, but also causes the cyclone to oscillate around a central position and slowly drift westward in a clockwise direction around the pole."
The new atmospheric model could help explain cyclonic motion not only on Jupiter, but potentially on other planets, including Earth.
"One of the great things about Juno is that its orbit is constantly changing, which means we get new vantage points every time we fly science," Bolton said. "In the extended mission, that means we'll continue to explore places no spacecraft has gone before, including staying longer in the solar system's most intense planetary radiation belts. It's a little scary, but we've built Juno like a tank, and every time we fly through it, we'll learn more about this intense environment."
Juno is a NASA spacecraft designed to explore Jupiter's atmosphere, magnetic field and deep interior structure, providing an unprecedented view of the largest planet in the solar system. The mission is managed by NASA's Jet Propulsion Laboratory (JPL, part of the California Institute of Technology in Pasadena, California), and the principal investigator is Scott Bolton of the Southwest Research Institute in San Antonio, Texas.
Juno is part of NASA's New Frontiers program, which supports high-priority solar system exploration missions and is managed by NASA's Marshall Space Flight Center in Huntsville, Alabama, for the Science Mission Directorate in Washington, DC.
The spacecraft itself was built and operated by Lockheed Martin Spaceflight in Denver. Juno's suite of cutting-edge science instruments includes the Jupiter Infrared Auroral Mapper (JIRAM), funded by the Italian Space Agency. Many other research institutions across the United States have contributed additional instruments, making Juno a highly collaborative, international mission.
Since arriving at Jupiter in 2016, Juno has provided stunning data and images, revealing the gas giant's dynamic atmosphere, deep storms, powerful aurora and mysterious core, while enduring some of the harshest radiation conditions in the solar system.
Compiled from /ScitechDaily