Jupiter’s moon Io, known as the most volcanically active body in the Solar System, has once again astonished scientists with the discovery of a new volcano. NASA’s Juno spacecraft, which has been making closer approaches to Io in recent years, provided the first close-up images of the moon in 25 years, offering fresh insights into its volcanic landscape.
The images captured by JunoCam revealed the presence of a new volcano, located just south of Io’s equator. This volcano had formed sometime after NASA’s Galileo spacecraft last surveyed the region in 1997. At that time, the area where the volcano now sits appeared featureless. However, Juno’s latest images show significant volcanic activity, with multiple lava flows and volcanic deposits spread across an area of 180 by 180 kilometers.
Io’s Volcanic Activity
Io’s volcanic activity is driven by tidal heating caused by gravitational interactions with its parent planet, Jupiter, and its neighboring moon, Europa. This constant flexing of Io’s interior generates immense heat, which, unlike in its sibling moons with subsurface oceans, causes magma to rise to the surface. With over 400 active volcanoes, Io is a constantly changing world, its surface coated with sulfuric compounds that give it vibrant colors.
The new volcano discovered by Juno lies near an existing one called Kanehekili. The images from February 2024 provide an unprecedented view of the region, highlighting the dynamic nature of Io’s surface. The volcanic feature, though appearing to have formed quickly, is a result of the ongoing tidal stresses that have reshaped Io’s landscape for eons.
A Closer Look at Io
JunoCam’s best image of the new volcano was taken on February 3, 2024, from a distance of approximately 2,530 kilometers. The image, taken at a resolution of 1.7 kilometers per pixel, shows Io illuminated by sunlight reflected off of Jupiter, offering a detailed view of the volcanic activity. A comparison of images from Galileo and JunoCam highlights the dramatic changes on Io’s surface over the past two decades.
Michael Ravine, Advanced Projects Manager at Malin Space Science Systems, the company responsible for JunoCam, remarked, “Our recent JunoCam images show many changes on Io, including this large, complicated volcanic feature that appears to have formed from nothing since 1997.”
While Juno’s discovery is significant, it also raises new questions about Io’s volcanic history and interior structure. Scientists have long understood that tidal heating from Jupiter is Io’s primary heat source, but how this heat is distributed within the moon remains uncertain. Additionally, researchers are still investigating the extent of Io’s subsurface magma ocean, the triggers for volcanic eruptions, and the various types of volcanic activity observed on the moon.
The Future of Io Exploration
Io’s surface is remarkably young, as evidenced by the lack of impact craters. This suggests that volcanic activity continuously reshapes the landscape, with eruptions spewing gas, lava, and pyroclastic flows. Scientists are eager to understand how these eruptions influence Io’s thin atmosphere and surface conditions.
Though Juno will continue to make flybys of Io, including several more in the coming years, it won’t be able to provide the in-depth answers researchers seek. The spacecraft’s closest approach to Io occurred during its 58th perijove (closest approach to Jupiter) in 2024. Future flybys will take Juno further from the moon, limiting the level of detail it can capture. The final close flyby of Io will be in 2025, at a distance of around 94,000 kilometers.
Despite this, JunoCam’s images have proven to be a valuable tool for scientific discovery. Although originally intended as a public outreach instrument, it has demonstrated its ability to contribute meaningfully to our understanding of Jupiter’s moons.
As scientists continue to study the new volcano and other features of Io’s turbulent surface, they hope to unlock further secrets about volcanic processes not only on Io but on other rocky planets as well. Juno’s observations have expanded our knowledge of the moon and its volcanic activity, setting the stage for future missions that may provide even more detailed insights into this fascinating world.