Volcanic Impact on Jupiter’s Moon Io Shown Directly for the First Time

Jupiter's Moon Io Composite Image

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Composite image proving Jupiter’s moon Io in radio (ALMA), and optical light (Voyager 1 and Galileo). The ALMA pictures of Io reveal for the very first time plumes of sulfur dioxide (in yellow) rise from its volcanoes. Jupiter shows up in the background (Hubble). Credit: ALMA (ESO/NAOJ/NRAO), I. de Pater et al.; NRAO/AUI NSF, S. Dagnello; NASA/ESA

New radio images from the Atacama Large Millimeter/submillimeter Array (ALMA) reveal for the very first time the direct result of volcanic activity on the environment of Jupiter’s moon Io.

Io is the most volcanically active moon in our planetary system. It hosts more than 400 active volcanoes, gushing out sulfur gases that offer Io its yellow-white-orange-red colors when they freeze out on its surface area.

Although it is exceptionally thin – about a billion times thinner than Earth’s environment – Io has an environment that can teach us about Io’s volcanic activity and supply us a window into the unique moon’s interior and what is taking place listed below its vibrant crust.

Previous research study has actually revealed that Io’s environment is controlled by sulfur dioxide gas, eventually sourced from volcanic activity. “However, it is not known which process drives the dynamics in Io’s atmosphere,” stated Imke de Pater of the University of California, Berkeley. “Is it volcanic activity, or gas that has sublimated (transitioned from strong to gaseous state) from the icy surface area when Io remains in sunshine?“

To compare the various procedures that trigger Io’s environment, a group of astronomers utilized ALMA to make photos of the moon when it passed in and out of Jupiter’s shadow (they call this an “eclipse”).

This video reveals pictures of Jupiter’s moon Io in radio (made with ALMA), and optical light (made with Voyager 1 and Galileo objectives). The ALMA images were taken when Io entered Jupiter’s shadow in March 2018 (eclipse), and from Jupiter’s shadow into sunshine in September 2018. These radio images for the very first time reveal plumes of sulfur dioxide (in yellow) rise from the volcanoes on Io. Credit: ALMA (ESO/NAOJ/NRAO), I. de Pater et al.; NRAO/AUI NSF, S. Dagnello; NASA

“When Io passes into Jupiter’s shadow, and is out of direct sunlight, it is too cold for sulfur dioxide gas, and it condenses onto Io’s surface. During that time we can only see volcanically-sourced sulfur dioxide. We can therefore see exactly how much of the atmosphere is impacted by volcanic activity,” discussed Statia Luszcz-Cook from Columbia University, New York.

Thanks to ALMA’s beautiful resolution and level of sensitivity, the astronomers could, for the very first time, plainly see the plumes of sulfur dioxide (SO2) and sulfur monoxide (SO) rise from the volcanoes. Based on the photos, they determined that active volcanoes straight produce 30-50 percent of Io’s environment.

The ALMA images likewise revealed a 3rd gas coming out of volcanoes: potassium chloride (KCl). “We see KCl in volcanic regions where we do not see SO2 or SO,” stated Luszcz-Cook. “This is strong evidence that the magma reservoirs are different under different volcanoes.”

Io is volcanically active due to a procedure called tidal heating. Io orbits Jupiter in an orbit that is not rather circular and, like our Moon constantly deals with the very same side of Earth, so does the very same side of Io constantly face Jupiter. The gravitational pull of Jupiter’s other moons Europa and Ganymede triggers remarkable quantities of internal friction and heat, triggering volcanoes such as Loki Patera, which covers more than 200 kilometers (124 miles) throughout. “By studying Io’s atmosphere and volcanic activity we learn more about not only the volcanoes themselves, but also the tidal heating process and Io’s interior,” included Luszcz-Cook.

A huge unknown stays the temperature level in Io’s lower environment. In future research study, the astronomers intend to determine this with ALMA. “To measure the temperature of Io’s atmosphere, we need to obtain a higher resolution in our observations, which requires that we observe the moon for a longer period of time. We can only do this when Io is in sunlight since it does not spend much time in eclipse,” stated de Pater. “During such an observation, Io will rotate by tens of degrees. We will need to apply software that helps us make un-smeared images. We have done this previously with radio images of Jupiter made with ALMA and the Very Large Array (VLA).”

Reference: “ALMA Observations of Io Going into and Coming out of Eclipse” by Imke de Pater, Statia Luszcz-Cook, Patricio Rojo, Erin Redwing, Katherine de Kleer and Arielle Moullet, 21 October 2020, Planetary Science Journal.
DOI: 10.3847/PSJ/abb93d

The National Radio Astronomy Observatory is a center of the National Science Foundation, run under cooperative contract by Associated Universities, Inc.