A spectroscopic map of Ganymede and an infrared image of Io by James Webb

New observations by James Webb show Ganymede and Io like never before

Ganymede, the largest moon in the solar system, and Io, famously recognized for its extreme volcanic activity.


The state-of-the-art James Webb Space Telescope has made new observations of  Ganymede and Io, showing the Jovian moons like never before.

The enigmatic moons of Jupiter are no longer quite so mysterious. Scientists, using the state-of-the-art James Webb Space Telescope (JWST), have uncovered new insights into two of Jupiter’s most notable satellites: Ganymede, the largest moon in the solar system, and Io, famously recognized for its extreme volcanic activity.

The remarkable findings, including the detection of hydrogen peroxide on Ganymede and sulfurous emissions on Io, represent a significant leap in our understanding of these celestial bodies.

A Breakthrough in the Exploration of Ganymede’s Polar Chemistry

In a groundbreaking discovery, astronomers utilizing JWST’s Early Release Science program have reported the presence of hydrogen peroxide on Ganymede. Samantha Trumbo, a postdoctoral fellow at Cornell University, led the study, which demonstrates how charged particles impacting Ganymede’s icy surface can alter the moon’s polar chemistry.

Trumbo explained, “This revelation of hydrogen peroxide at Ganymede’s poles exemplifies how charged particles, guided by Ganymede’s magnetic field, can uniquely change the chemical makeup of its polar regions.” Unlike other moons, Ganymede has a magnetic field that sends charged particles toward its poles, where they create aurorae and transform the ice.


Understanding Water Radiolysis and Its Implications”

These findings on Ganymede are not an isolated event. Previous studies of Europa, another Galilean satellite, detected hydrogen peroxide across its surface. The newfound knowledge about Ganymede gives scientists valuable insights into water radiolysis, a process likely to affect icy bodies throughout the outer solar system. “This helps us comprehend how this so-called radiolysis operates, validating theories based on Earth’s laboratory experiments,” stated Imke de Pater, professor emerita at the University of California, Berkeley.

Io’s Volcanic Mystery Revealed

In another compelling discovery, de Pater and colleagues unveiled Webb’s observations of Io’s ongoing volcanic eruptions. They were able to link a volcanic eruption at Kanehekili Fluctus to a particular emission produced by the gas sulfur monoxide (SO).

“These observations with Webb are the first to prove that this excited SO comes directly from a volcano,” de Pater remarked. This link between SO and volcanoes supports a hypothesis from 2002 and further enlightens scientists about the volcanic mechanisms on Io, the solar system’s only moon with volcanic activity.

A Bright Future in Planetary Exploration

The James Webb Space Telescope is not just limiting its gaze to Jupiter’s moons. It has already started focusing on the planetary systems of Saturn, Uranus, and Neptune. The telescope’s precise observations and the unraveling of secrets about Ganymede and Io highlight a bright future in planetary exploration that promises to deepen our understanding of the universe.

These pioneering findings mark a new era in space exploration and the study of Jupiter’s enigmatic moons. By harnessing the power of JWST, scientists are gaining unprecedented insights into these celestial bodies’ chemistry, geology, and volcanic activity.


The world’s most advanced telescope has only just begun to scratch the surface of what lies beyond our earthly realm, paving the way for future revelations that could reshape our understanding of the cosmos.

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Written by Ivan Petricevic

I've been writing passionately about ancient civilizations, history, alien life, and various other subjects for more than eight years. You may have seen me appear on Discovery Channel's What On Earth series, History Channel's Ancient Aliens, and Gaia's Ancient Civilizations among others.

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