During two close flybys, the Juno spacecraft collected data that allow scientists to infer the temperature below Io’s surface. The measurements indicate notable heating in the shallow subsurface, which is likely linked to the moon’s intense volcanic activity.
Io is recognized as the most volcanically active body in the Solar System. The new temperature profiles show that heat extends not only at the surface but also several centimeters beneath it, suggesting an efficient internal heat transport mechanism.
Furthermore, the data reveal that most of Io’s surface is remarkably smooth and composed of material with very low density. This points to a porous, possibly sulfur‑rich regolith that has been reshaped by continual eruptions.
These findings improve our understanding of Io’s geothermal system and provide constraints for models of tidal heating and interior dynamics in heavily stressed moons.