Jupiter’s moon Io imaged by SHARK-VIS on January 10, 2024. This is the highest-resolution image of Io ever obtained by an Earth-based telescope. The image combines three spectral bands—infrared, red, and yellow—to highlight the reddish ring around Pele volcano (below and to the right of the moon’s center) and the white ring around Pilan Patera, to the right of Pele. Courtesy of: INAF/Large Binocular Telescope Observatory/Georgia State University; IRV-band observations from SHARK-VIS/F. Pedicini; processing D. Hope, S. Jeffries, G. Lee Causey
Astronomers have caught a volcanic event on Jupitermoon Io at a resolution never before achieved with ground-based observations, advancing our understanding of volcanic processes in the Solar System.
New images of Jupiter’s volcano-strewn moon Io taken by the Large Binocular Telescope on Mount Graham in Arizona offer the highest resolution of Io ever achieved by an Earth-based instrument. The observations were made possible by a new high-contrast optical imaging instrument called SHARK-VIS and the telescope’s adaptive optics system, which compensates for blurring caused by atmospheric turbulence.
Unprecedented details have been revealed
The images will be published in the magazine Geophysical Research Letters, reveal surface features 50 miles in diameter, a spatial resolution previously only achievable with spacecraft sent to Jupiter. That’s equivalent to taking a picture of a dime-sized object from 100 miles away, according to the research team.
SHARK-VIS allowed researchers to identify a major resurgence around Pele, one of Io’s most famous volcanoes. According to the paper’s first author, Al Conrad, eruptions on Io, the most volcanically active body in the Solar System, are fewer than their counterparts on Earth.
The Large Binocular Telescope Interferometer, or LBTI, is a ground-based instrument linking two 8-meter Mount Graham-class telescopes in Arizona to form the world’s largest single-mount telescope. The interferometer is designed to detect and study stars and planets outside our solar system. Credits: NASA/JPL-Caltech
Volcanic insights from Io
“Therefore, Io provides a unique opportunity to learn about the powerful eruptions that helped shape the surfaces of Earth and the Moon in their distant past,” said Konrad, associate scientist at the Large Binocular Telescope Observatory. The Large Binocular Telescope, or LBT, is part of the Mount Graham International Observatory, a division of the University of Arizona’s Steward Observatory.
Conrad added that studies like this will help researchers understand why some worlds in the Solar System are volcanic but not others. They may also someday shed light on volcanic worlds exoplanet systems around nearby stars.
Gravitational dynamics and volcanism
Slightly larger than Earth’s moon, Io is the innermost of Jupiter’s Galilean moons, which in addition to Io include Europa, Ganymede, and Callisto. Locked in a gravitational ‘tug of war’ between Jupiter, Europa and Ganymede, Io is constantly squeezed, causing heat to build up in its interior – thought to be the cause of its continued and widespread volcanic activity.
By observing eruptions on Io’s surface, scientists hope to gain insight into the heat-driven movement of material beneath the moon’s surface, its internal structure, and ultimately the tidal heating mechanism responsible for Io’s intense volcanism.
A cross-section through Io’s crust depicting scientists’ current understanding of the geological and chemical processes that sculpt the surface and create the moon’s atmosphere. To the left is a fin and a red ring of sulfur similar to that generated by the Pele lava lake. Faults in the mostly cold lithosphere act as pathways for sulfur-rich silicate magma to reach the surface. Io’s interior is heated by friction caused by the gravitational pull of Jupiter and two of its moons, Europa and Ganymede, which generate molten magma. Credit: de Pater et al., 2021, Annual Reviews based on a figure by Doug Beckner, James Tuttle Keen, Ashley Davis
Historical context and recent discoveries
Volcanic activity on Io was first discovered in 1979 when Linda Morabito, an engineer at NASAThe Voyager mission spotted the eruption jet in one of the images taken by the spacecraft during its famous “Grand Tour” of the outer planets. Since then, countless observations have been made that document Io’s restless nature, both from space and ground-based telescopes.
Study co-author Ashley Davis, principal scientist at NASA’s Jet Propulsion Laboratory (JPL), said the new image taken by SHARK-VIS was so rich in detail that it allowed the team to identify a major resurfacing event in which the plume was deposited around a prominent volcano known as Pele, located in the southern Io’s hemisphere near the equator. , is covered by deposits from an eruption from Pilan Patera, a neighboring volcano. A similar sequence of eruptions was observed by NASA’s Galileo spacecraft, which explored the Jupiter system between 1995 and 2003.
Technological advances in ground-based observations
“We interpret the changes as dark lava deposits and white sulfur dioxide deposits originating from an eruption at Pilan Patera that partially cover the red, sulfur-rich deposits of Pele’s jet,” Davis said. “Prior to SHARK-VIS, such surface events were impossible to observe from Earth.”
While infrared telescope images can detect hot spots caused by ongoing volcanic eruptions, they are not sharp enough to reveal surface details and unequivocally identify the locations of eruptions, explained co-author Imke de Pater, professor emeritus of astronomy at the University of California – Berkeley.
“Sharper images at visible wavelengths, such as those provided by SHARK-VIS and LBT, are essential for identifying both the locations of eruptions and surface changes not detectable in the infrared, such as new plume deposits,” de Pater said, adding that visible-light observations provide researchers with vital context for interpreting infrared observations, including those from spacecraft such as Juno, which is currently orbiting Jupiter.
Technological advances in observational astronomy
SHARK-VIS was built by the Italian National Institute of Astrophysics at the Rome Astronomical Observatory and is operated by a team led by Principal Investigator Fernando Pedicini, assisted by Project Manager Roberto Piazesi. In 2023, it was installed, along with its companion near-infrared instrument SHARK-NIR, on the LBT to take full advantage of the telescope’s outstanding adaptive optics system. The instrument features a fast, ultra-low-noise camera that allows it to observe the sky in “quick image” mode, capturing slow-motion footage that freezes the optical distortions caused by atmospheric turbulence, and processing data to unprecedented sharpness.
Gianluca Li Causi, data processing manager for SHARK-VIS at the Italian National Institute of Astrophysics, explained how it works: “We process our data on the computer to remove any trace of the sensor’s electronic fingerprint. We then select the best frameworks and combine them using a highly efficient software package called Kraken, developed by our colleagues Douglas Hope and Stuart Jeffries at Georgia State University. Kraken allows us to remove atmospheric effects, revealing Io in incredible sharpness.”
Future Perspectives in Solar System Observation
SHARK-VIS instrument scientist Simone Antoniucci said he expects new observations of objects throughout the Solar System to be made.
“Shark-VIS’s sharp vision is particularly suited to observing the surfaces of many solar system bodies, not only the moons of giant planets, but also asteroids,” he said. “We’ve already observed some of them, with the data being analyzed now, and we plan to observe more.”
