Juno Probe Detects Subsurface Heat on Volcanic Moon Io

The study, published in the Journal of Geophysical Research: Planets, utilizes data from Juno’s Microwave Radiometer (MWR). Originally engineered to probe the deep atmosphere of Jupiter, the instrument allowed scientists to record thermal emissions from depths ranging from a few inches to several feet. During encounters on December 30, 2023, and February 3, 2024, the probe passed within 930 miles of the surface, revealing temperature spikes exceeding 40 degrees Fahrenheit that solar radiation cannot account for.

Scott Bolton, principal investigator at the Southwest Research Institute, noted that this capability provides a new window into tidal heating—the process where Jupiter’s immense gravity stretches and compresses the moon, generating massive internal energy. While researchers previously relied on infrared data to track surface lava, this technique exposes how heat migrates through the crust. Lead author Shannon Brown of the Jet Propulsion Laboratory suggests these findings may eventually refine models for studying volcanic activity on Earth by identifying similar underground thermal patterns.