NASA’s James Webb Space Telescope has helped scientists discover a new moon orbiting Uranus, bringing the planet’s total to 29. The small moon was spotted on February 2, 2025, by a team from the Southwest Research Institute (SwRI).
Scientists found the tiny moon in ten long-exposure images taken by NASA’s Webb Telescope. Though small, it’s a significant find, one that Voyager 2 missed when it flew past Uranus nearly 40 years ago.
The new moon is incredibly small, only about six miles (10 kilometers) wide, based on how reflective it seems compared to Uranus’s other moons. Its tiny size likely made it too faint for Voyager 2 or earlier telescopes to detect, hiding in plain sight for decades.
Matthew Tiscareno of the SETI Institute in Mountain View, California, a member of the research team, said, “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.”
“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.”
The newly discovered moon is the 14th in Uranus’s tightly packed group of small inner moons, orbiting closer to the planet than its five major moons—Miranda, Ariel, Umbriel, Titania, and Oberon. (Fun fact: all Uranian moons are named after characters from Shakespeare and Alexander Pope.)
This tiny moon circles Uranus about 35,000 miles (56,000 kilometers) from its center, gliding between the orbits of Ophelia and Bianca. Its nearly perfect circular path hints that it likely formed right where it is, quietly holding its place in the planet’s complex lunar ballet.
El Moutamid said, “Through this and other programs, Webb is providing a new eye on the outer solar system. This discovery comes as part of Webb’s General Observer program, which allows scientists worldwide to propose investigations using the telescope’s cutting-edge instruments. The NIRCam instrument’s high resolution and infrared sensitivity make it especially adept at detecting faint, distant objects that were beyond the reach of previous observatories.”
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. Now, nearly four decades later, the James Webb Space Telescope is pushing that frontier even farther.”