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New results on the moons of Jupiter

Published Mar 17, 2021

Researchers from SPP publish new results

The atmosphere of Jupiter’s moon Io – the most volcanic moon in the solar system - consists mostly of sulfur dioxide (SO2) and is sustained by two competing sources: direct outgassing from active volcanoes and sublimation of frost deposits on the surface. While the volcanic outgassing source undergoes rather random and aperiodic changes, changes in sublimation are seasonal. In a recent SPP study ( ), we (Gabriel Giono and Lorenz Roth) have investigated observations of Io’s SO2 atmosphere by the Hubble Space Telescope taken on various occasions over almost two Jupiter years (~19 years). We searched for both local changes due to activity at volcanic regions and long-term changes due to the changing distance to the Sun. Overall, we found a rather stable atmosphere and did not detect local, transient or strong global changes. The non-detection of changes might be due to the limitations of the particular observing method, which we have characterized in detail in our study for the first time.

The atmosphere of Io is densest at the equator, where it absorbs the solar light (dark region in the images). We have looked at specific regions in the Hubble Space Telecope observations (colored dots) and analyzed the image-quality – such as the signal-to-noise ratio - in detail. The figure has been selected as cover by the Icarus journal (

In another SPP project on the moons of Jupiter, we investigated the generation of aurora in the atmosphere of Io as well as of neighboring moon Europa. The recently finished project ‘AuroraMHD’ simulated to plasma interactions that create the moon auroras, which have implications for other aspects such as moon Europa’s potential to support life .