In 1986, Voyager 2 discovered 10 moons around Uranus. 39 years later, Webb found a 29th moon only 10 kilometre wide that the spacecraft had missed

In 1986, Voyager 2 discovered 10 moons around Uranus during its flyby. Thirty-nine years later, James Webb Space Telescope observations identified S/2025 U1, a moon about 10 kilometres wide between Ophelia and Bianca. The discovery raised the known number of Uranus moons to 29 and showed that small objects can remain hidden among the planet’s rings and inner satellites.