Juno Snaps Rare Close-Up of Jupiter's Tiny Moon Thebe
Breaking: Juno Captures Unprecedented Image of Thebe
NASA's Juno spacecraft has transmitted a stunning new image of Jupiter's small moon Thebe, revealing surface details never before seen up close. The photo, taken during Juno's 66th perijove on May 5, 2026, shows the irregularly shaped moon against the backdrop of Jupiter's swirling cloud tops.
"This is the highest-resolution image of Thebe ever obtained," said Dr. Emily Garcia, Juno mission scientist at NASA's Jet Propulsion Laboratory. "We are seeing features down to about 1 kilometer across, which opens a window into the moon's history and composition."
Image Details and Significance
The image was captured by Juno's JunoCam instrument from a distance of approximately 350,000 kilometers. Thebe is one of Jupiter's four inner small moons, discovered in 1979 by Voyager 1, and measures only about 116 by 98 kilometers in diameter.
"Thebe's surface is heavily cratered, and we can now see a prominent impact crater that appears to have a bright ray system," noted Dr. Garcia. "This suggests the moon has experienced relatively recent impacts and may have a complex geological history."
Background: The Juno Mission and Jupiter's 'Small Moons'
Juno entered Jupiter's orbit in July 2016 on a mission to study the planet's atmosphere, magnetic field, and gravity field. The spacecraft has been gradually shifting its orbit to fly closer to Jupiter's poles, allowing occasional close passes of its inner moons.
Thebe, also designated Jupiter XIV, orbits Jupiter at a distance of about 222,000 kilometers, inside the orbit of the larger moon Amalthea. Its irregular shape and low density suggest it is likely a captured asteroid or a fragment of a larger moon.
Previous images from Voyager, Galileo, and New Horizons provided only fuzzy glimpses of Thebe. Juno's latest observation represents a major leap in resolution, comparable to seeing a football field from a mile away.
What the Image Reveals
Scientists have already identified several craters and a ridge-like structure running across the moon's equator. The bright ray crater appears to ejecta material that may have been thrown up by a relatively recent impact—perhaps within the last few million years.
"Thebe's surface is dark and reddish, typical of Jupiter's inner moons, but the fresh crater stands out like a beacon," said Dr. Michael Torres, a planetary scientist at the University of Arizona not involved in the mission. "This could help us understand the population of impactors in the Jupiter system."
What This Means for Planetary Science
This close-up of Thebe provides crucial data for models of how Jupiter's small moons formed and evolved. The moon's density, estimated at about 0.86 grams per cubic centimeter, indicates it is porous and likely composed of water ice mixed with rocky material.
"Understanding Thebe helps us piece together the history of the entire Jovian system," emphasized Dr. Garcia. "These small moons are the building blocks that may have influenced the formation of the larger Galilean moons."
Furthermore, the image will help refine orbital models for Jupiter's moons, which is essential for future missions such as NASA's Europa Clipper (arriving in 2030) and the European Space Agency's JUICE mission (already en route).
"Every new observation of these tiny worlds reduces uncertainties in their orbits and physical properties," added Dr. Torres. "That's critical for planning close flybys of Europa and Ganymede without colliding with debris."
Next Steps for Juno
Juno's mission has been extended through 2027, with several more close passes of Jupiter's inner moons planned. The spacecraft may target Thebe again or attempt to image the even smaller moon Metis, which has never been imaged in detail.
"We are just scratching the surface," concluded Dr. Garcia. "Each perijove brings new surprises, and we expect to release more Thebe images and data in the coming weeks."
For more on Juno's ongoing discoveries, see our Background section or the What This Means analysis above.