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For nearly four decades, Uranus’ family of moons seemed complete. Voyager 2, humanity’s only spacecraft to ever visit the ice giant, swept past in 1986 and revealed a stunning array of rings and satellites. But on February 2, 2025, the James Webb Space Telescope (JWST) showed us that Uranus still has secrets to share.
A research team led by the Southwest Research Institute (SwRI) has identified a previously unknown moon orbiting Uranus—bringing the planet’s known satellite count to 29. The discovery was made using Webb’s Near-Infrared Camera (NIRCam), which captured ten deep, 40-minute exposures of the system.
“This object was spotted in a series of long-exposure images,” explained Maryame El Moutamid, lead scientist in SwRI’s Solar System Science and Exploration Division. “It’s a small moon, but a significant discovery—one that even Voyager 2 didn’t detect during its historic flyby almost 40 years ago.”
The newly found moon is tiny by cosmic standards, measuring just six miles (10 kilometers) across—about the size of a city. Assuming it reflects sunlight much like Uranus’ other inner moons, its faint glow would have been invisible to Voyager 2 and other telescopes.
“No other planet has as many small inner moons as Uranus,” said Matthew Tiscareno of the SETI Institute, a co-investigator on the project. “Their interactions with the planet’s rings tell a story of a chaotic past where the line between ring and moon is blurred. This new moon is smaller and fainter than any previously known, which suggests Uranus’ system may hold even more surprises.”
This faint newcomer circles Uranus at a distance of 35,000 miles (56,000 kilometers), nestled between the orbits of Ophelia (a shepherd moon near the planet’s main rings) and Bianca. Its nearly circular orbit hints that it formed close to where it is today.
The new object is the 14th small inner moon, joining the ranks beneath Uranus’ larger moons—Miranda, Ariel, Umbriel, Titania, and Oberon. True to tradition, its future name will be drawn from the works of William Shakespeare or Alexander Pope, pending approval from the International Astronomical Union (IAU).
For astronomers, the discovery highlights the cutting-edge power of Webb. “Through this and other programs, Webb is providing a new eye on the outer solar system,” El Moutamid said. “Its infrared sensitivity makes it possible to detect faint worlds we never could before. This moon is a reminder that Voyager 2 gave us our first close-up glimpse of Uranus, but modern astronomy is far from finished with this strange planet.”
Nearly 40 years after Voyager 2’s flyby, Uranus’ story is still being written—one hidden moon at a time.