PREVIEW

This animated tour of Jupiter’s fiery moon Io, based on data collected by NASA’s Juno mission, shows volcanic plumes, a view of lava on the surface, and the moon’s internal structure.

NASA’s Juno mission has shed light on the extraordinary volcanic activity of Jupiter’s moon Io, revealing the source of its fiery eruptions.

Io, the most volcanically active body in the solar system, hosts over 400 volcanoes that spew lava and plumes across its surface. For decades, scientists have debated whether these eruptions are powered by a global ocean of magma or more localised reservoirs beneath the surface.

New data from Juno’s close flybys in December 2023 and February 2024, which brought the spacecraft within 1,500 kilometres of Io’s surface, indicate that the volcanoes are fuelled by individual magma chambers rather than a planet-wide ocean.

By analysing gravity measurements from Io’s tidal flexing—caused by the immense gravitational pull of Jupiter as the moon’s elliptical orbit brings it closer and further from the gas giant—scientists determined that the deformation patterns align with a mostly solid interior. This finding challenges the long-held assumption of a global magma ocean, instead suggesting a more complex subsurface structure.

Published in Nature, the study has far-reaching implications, offering new insights into the geologic activity of other celestial bodies such as Europa, Enceladus, and even distant exoplanets.

Juno’s principal investigator, Scott Bolton, described Io as a “laboratory” for studying tidal heating, the process by which gravitational forces generate internal heat. The research not only enhances understanding of Io’s volcanic origins but also provides a fresh perspective on planetary formation and evolution.

Io’s violent eruptions were first discovered in 1979 when a NASA Voyager 1 image captured a volcanic plume, and the moon’s geologic complexity continues to captivate scientists. Juno’s mission, which has been orbiting Jupiter since 2016, is set to continue exploring the Jovian system, with its next close approach to Jupiter scheduled for late December.