NASA’s Juno probe has begun mapping the hidden heat sources beneath the surface of Io, the most volcanically active moon in the solar system. During two close flybys in December 2023 and February 2024, Juno’s Microwave Radiometer (MWR) instrument collected data that will allow scientists to better understand the distribution of Io’s internal heat and the mechanisms driving its extreme volcanism. These flybys occurred during the mission's Perijoves 57 and 58, respectively.

Juno’s MWR is capable of penetrating Io’s surface layers, providing a three-dimensional view of the temperature beneath the crust. In the December 30, 2023 flyby (Perijove 57), the probe primarily focused on the moon’s northern hemisphere. Subsequently, in the February 3, 2024 flyby (Perijove 58), Juno mapped additional regions, complementing the previous data and offering more comprehensive coverage of the thermal distribution. This capability is crucial, as infrared observations can only detect surface heat, while the MWR can reveal thermal anomalies at greater depths.

The information obtained by Juno is fundamental to unraveling the mystery of how Jupiter's tidal forces generate so much internal heat within Io. Understanding the distribution of hidden heat will help researchers more accurately model the geophysical processes that drive the moon's volcanic activity, including the formation of its vast lava lakes and volcanic plumes. These data will be compared with theoretical models of tidal heating to refine our understanding of Io's evolution and that of other celestial bodies with active volcanism in the solar system and beyond.