Beth’s favorite moon, Io, the smallest of Jupiter’s Galilean moons, has dunes, which is… strange if you think about the fact that Io is an incredibly volcanic world without an atmosphere. And dunes on Earth and on Mars form with wind, which, again, usually requires an atmosphere.

This turns out to have been a long-standing question, as the dunes were originally captured in images taken by the Galileo spacecraft. Those same images also showed a world that is being repeatedly and constantly resurfaced by volcanoes.

That volcanic surface consists of black, solidified lava flows, flowing lava streams, and even ashfall made of frozen sulfur dioxide. Now, a team of scientists led by George McDonald from Rutgers University has used mathematical modeling to find a possible answer for how those dunes came to exist. When the lava flows into the sulfur dioxide under Io’s surface, venting happens. And as McDonald explains: [That venting is] dense and fast-moving enough to move grains on Io and possibly enable the formation of large-scale features like dunes.

Once the team had a possible mechanism and some maths to back them up, they went back to those Galileo images for proof and found that the spacing of the dunes as well as their height-to-width ratios matched what we see in similar dunes here on Earth and elsewhere in the solar system.

This work was published in Nature Communications.

More Information

Rutgers press release

“Aeolian sediment transport on Io from lava–frost interactions,” George D. McDonald et al., 2022 April 19, Nature Communications