James Webb Detects 10-Km Uranus Moon, Lifting Known Total to 29
Updated
Updated · spacedaily.com · Jun 25
James Webb Detects 10-Km Uranus Moon, Lifting Known Total to 29
3 articles · Updated · spacedaily.com · Jun 25
Summary
S/2025 U1, a faint moon about 10 kilometers wide, was spotted near Uranus’s inner rings in Webb observations from February 2, 2025, adding a 29th known moon to the planet’s tally.
Ten 40-minute NIRCam exposures enabled the detection, with Webb’s infrared sensitivity and larger mirror separating the object from Uranus’s glare after Voyager 2 and Hubble failed to see it.
At roughly 56,000 kilometers from Uranus’s center, the moon orbits between Ophelia and Bianca in less than half a day on a near-circular path, placing it firmly in the crowded inner moon-and-ring system.
That location matters because Uranus’s small inner moons help shape ring edges, move dust and trace the system’s chaotic evolution, suggesting the planet’s moon inventory may still be incomplete.
The find also underscores how little direct exploration Uranus has had since Voyager 2’s 1986 flyby, strengthening the case for a future orbiter to map rings and search for more hidden bodies.