Astronomers have identified a previously unknown moon orbiting Uranus using NASA’s James Webb Space Telescope, raising the planet’s tally of confirmed satellites to 29. The object, provisionally designated S/2025 U1, was detected in ten 40-minute exposures captured on 2 February 2025 by Webb’s Near-Infrared Camera, according to a research team led by the Southwest Research Institute. At roughly six miles (about ten kilometres) across, S/2025 U1 is the smallest Uranian moon yet found and too faint to have been spotted by earlier missions, including Voyager 2’s 1986 fly-by. The body orbits about 35,000 miles (56,000 kilometres) from the planet’s centre, nestled between the inner moons Ophelia and Bianca on a near-circular path that suggests it formed close to its present location. Scientists say the discovery underscores JWST’s ability to probe the dim, crowded environment inside Uranus’s ring system, where 14 miniature moons mingle with dusty rings. The International Astronomical Union will assign an official Shakespeare-themed name in due course, and researchers expect additional moons may emerge as Webb continues its survey of the outer solar system.