Free Astronomy Magazine January-February 2021

22 JANUARY-FEBRUARY 2021 ASTRO PUBLISHING by ALMA Observatory N ew radio images from the At- acama Large Millimeter/sub- millimeter Array (ALMA) show for the first time the direct ef- fect of volcanic activity on the at- mosphere of Jupiter’s moon Io. Io is the most volcanically active moon in our solar system. It hosts more than 400 active volcanoes, spewing out sulfur gases that give Io its yellow-white-orange-red col- ors when they freeze out on its surface. Although extremely thin (about a billion times thinner than Earth's atmosphere), Io’s atmos- phere can teach us something about volcanic activity and the in- terior of that exotic moon, and what is happening beneath its col- orful crust. Previous research has shown that Io’s atmosphere is dom- inated by sulfur dioxide gas, ulti- mately sourced from volcanic ac- tivity. “However, it is not known which process drives the dynamics in Io’s atmosphere ,” said Imke de Pater of the University of Califor- ALMA shows volcanic impact on Io’s atmosphere C omposite image showing Jupiter’s moon Io in radio (ALMA), and optical light (Voyager 1 and Galileo). The ALMA images of Io show for the first time plumes of sulfur dioxide (in yellow) rise up from its volcanoes. Jupiter is visible in the background (Cassini image). [ALMA (ESO/NAOJ/NRAO), I. de Pater et al.; NRAO/AUI NSF, S. Dagnello; NASA]