A new moon has been discovered orbiting Uranus, bringing the total number of known moons around the planet to 29. The James Webb Space Telescope (JWST) captured the tiny celestial object on February 2, 2025. Measuring approximately 10 kilometers (6 miles) across, this moon, designated S/2025 U1, marks a significant finding, as it was previously undetected by earlier missions, including the Voyager 2 probe, which passed by Uranus in 1986.
Located outside the planet’s delicate rings, S/2025 U1’s discovery emphasizes the complexity of the Uranian system. According to Matthew Tiscareno, a planetary scientist at the SETI Institute, “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.” The presence of such a small moon suggests that more undiscovered objects may exist within this dynamic environment.
The tiny moon was identified using JWST’s near-infrared NIRCam, which observed Uranus for over six hours to study its surroundings. S/2025 U1 orbits at a distance of 56,250 kilometers from Uranus’s center, situated amid 13 other small moons that orbit within the path of the larger moon Miranda. Its nearly circular orbit indicates that it likely formed in its current position, nestled between the moons Ophelia and Bianca.
As of now, S/2025 U1 has not been formally named. Traditionally, moons of Uranus are named after characters from the works of playwright William Shakespeare or poet Alexander Pope, so an appropriately poetic name is expected.
Maryame El Moutamid, an astronomer at the Southwest Research Institute, highlighted the significance of this discovery by stating, “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.” She added that the advancements made by the James Webb Space Telescope are extending our knowledge of the universe.
The findings from JWST not only enhance our understanding of Uranus but also encourage a renewed interest in further exploration of the planet. As astronomers continue to unravel the mysteries of the Uranian system, the potential for discovering even more moons and intricate details about this distant world remains tantalizing.
