Something incredible just happened in our own cosmic backyard. For the first time from Earth, scientists have watched as a volcanic eruption on a distant moon actually changed its surface. Using a powerful telescope system, they caught clear, visible signs of volcanic activity on Io, Jupiter’s wild and fiery moon—an alien world known for being the most volcanically active place in the Solar System. This breakthrough lets us witness planetary change as it happens, from millions of miles away.
A team led by Dr. Al Conrad at the Large Binocular Telescope Observatory made this discovery, which was published in Geophysical Research Letters, a journal that reports new findings in Earth and planetary science.
According to images from the SHARK-VIS camera installed on the Large Binocular Telescope, the team captured the most detailed pictures ever taken from Earth of Io’s surface using visible light—the same kind of light our eyes can see. These photographs revealed that part of a famous red ring created by the volcano Pele had been covered by new deposits. The new material, which appears both bright and dark in the images, likely came from a strong eruption at a neighboring volcano called Pillan Patera. These observations also help support data collected in heat-sensing studies, known as infrared observations, and from spacecraft flybys, which are brief passes by a planet or moon during a mission.
Something that makes this finding especially important is that it involves one of the most recognizable and long-lasting volcanic rings on Io. The red ring from Pele is formed by certain types of sulfur that do not last long unless constantly replaced by volcanic activity. But in the recent images, a large part of this ring had been buried under new frost made of frozen sulfur dioxide—a common gas from volcanoes—and darker ash-like material. Such a widespread covering hasn’t been observed since the late 1990s.
“These resurfacing events might be more common than we realized, but earlier telescopes just couldn’t show them clearly,” explained Dr. Conrad, describing the strength of the SHARK-VIS camera system. Pictures taken in late 2023 and early 2024 showed that the new bright deposit and its darker center stayed unchanged over several weeks. That steady presence suggests the eruption happened not long ago and had a strong impact.
Dr. Conrad’s team traced the source of the new material to a powerful eruption spotted in mid-2021 by different instruments that measure heat instead of light, which is useful for detecting volcanic activity. That eruption, described as a massive outburst, released a great deal of heat but didn’t last very long. Although it took more than two years before this area was photographed again, the SHARK-VIS images clearly show how the earlier eruption changed the moon’s surface. In contrast to a similar event in the 1990s—when Pele’s red ring returned within a couple of years—this time it seems to be taking longer, possibly because Pele hasn’t been erupting as strongly in recent years.
One possible reason the new deposits are still there is that Pele may not be as active as it once was, so it is not producing enough material to rebuild the red ring. Older data show that Pele’s heat output—or the total energy coming from the volcano—has dropped dramatically since earlier space missions. That decline might explain why the older red material has not returned. However, there was a brief increase in activity recorded in the spring of 2023, giving scientists a hint that Pele might still be capable of bigger eruptions.
Images taken by SHARK-VIS, which were sharpened using a special method that enhances fine details—called multi-frame deconvolution, where several images are combined to bring out clearer features—allowed researchers to spot changes on the surface as small as a few score miles across. That clarity matches what earlier space missions have achieved. It also shows how Earth-based tools can now compete with spacecraft when it comes to watching planetary surfaces. Being able to track these changes from Earth makes it easier to keep an eye on active areas and study how they evolve over time.
Dr. Conrad and colleagues’ findings represent a major moment in studying moons and planets from Earth. They show how using sharpened visible-light images can help scientists better understand how volcanoes and other surface processes work beyond our planet. Thanks to SHARK-VIS, experts can continue keeping watch on Io’s changing surface, gaining new knowledge about one of the most geologically active places in the Solar System.
Journal Reference
Conrad A., Pedichini F., Li Causi G., Antoniucci S., de Pater I., Davies A. G., et al. “Observation of Io’s Resurfacing via Plume Deposition Using Ground-Based Adaptive Optics at Visible Wavelengths With LBT SHARK-VIS.” Geophysical Research Letters, 2024. DOI: https://doi.org/10.1029/2024GL108609
About the Author
Dr. Al Conrad received his PhD in Computer Science from the University of California at Santa Cruz in 1994. Before joining LBT in 2014, he worked as software engineer and support astronomer at both Lick and Keck Observatories before moving to the Max Planck Institute for Astronomy to lead the development of the ground layer AO system for LINC-NIRVANA (LN). At LBT, Al has served as point of contact for LN, LBTI, and LUCI/AO commissioning. His current duties include the science archive, SHARK-NIR, SHARK-VIS, LN, and OSCO. His research interests include asteroid systems and developing novel techniques to study comets, planets, and the moons of planets, in particular Jupiter’s moon Io. He enjoys cycling, sailing, and outrigger canoe paddling.
