A new discovery has just brought the total number of Uranus’s known moons to 29.
In the space close to the icy planet, outside its ephemeral rings, JWST snapped a tiny object that no one had ever seen before, not even in data from the Voyager 2 probe that flew past Uranus at a close distance in 1986.
It’s probably just 10 kilometers (6 miles) across, and its discovery highlights the amazing intricacy of the Uranian system – and just how little we know about it.
Related: We’ve Just Found an Exoplanet That’s as Stinky as Uranus
“No other planet has as many small inner moons as Uranus, and their complex inter-relationships with the rings hint at a chaotic history that blurs the boundary between a ring system and a system of moons,” says planetary scientist Matthew Tiscareno of the SETI Institute.
“Moreover, the new moon is smaller and much fainter than the smallest of the previously known inner moons, making it likely that even more complexity remains to be discovered.”
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The tiny moon was spotted by JWST’s near-infrared NIRCam on 2 February 2025, when it spent more than 6 hours staring avidly at the planet to study it and its surroundings.
The object has been given the designation S/2025 U1, and it orbits amid the 13 other small moons interior to the orbit of the large moon Miranda at a distance of 56,250 kilometers from the planet’s center, around its unusual equatorial plane.
This orbit is sandwiched between the moons Ophelia and Bianca, which are outer and inner to its orbit, respectively. S/2025 U1 also has an orbit that is nearly circular, suggesting that it formed in its current location.
The moon is yet to be formally named. All moons of Uranus are named for characters from works by William Shakespeare or Alexander Pope, so something poetic is to be expected.
“Looking forward, the discovery of this moon underscores how modern astronomy continues to build upon the legacy of missions like Voyager 2, which flew past Uranus on January 24, 1986, and gave humanity its first close-up look at this mysterious world,” says astronomer Maryame El Moutamid of the Southwest Research Institute.
“Now, nearly four decades later, the James Webb Space Telescope is pushing that frontier even farther.”
Maybe it’s about time we went back.
