Astronomers identified over 100 previously unknown moons in our solar system during 2025, including dozens around Saturn and a new one orbiting Uranus. These findings, made using advanced telescopes, highlight ongoing mysteries in planetary formation. Experts suggest many more such satellites remain to be found.
In 2025, astronomers made significant strides in mapping our solar system's moons, uncovering more than 100 new ones that could refine our understanding of how planets form.
The year's discoveries began in March, when Edward Ashton at Academia Sinica in Taiwan and his team announced 128 new moons around Saturn. This increased the planet's known total to 274. The researchers achieved this by stacking hours of images from the Canada-France-Hawaii Telescope in Hawaii, revealing faint objects that would otherwise remain hidden. Ashton's group now holds naming rights for these moons, though Saturn's vast collection means many lack informal designations.
Later, in August, Maryame El Moutamid at Southwest Research Institute in Colorado and colleagues spotted a small, dim moon orbiting Uranus, raising its count to 29. The detection came from 10 long-exposure infrared images captured by NASA's James Webb Space Telescope. The moon bears the temporary label S/2025 U1, and it is expected to receive a name inspired by a Shakespeare play character, following a tradition that started with the planet's first moons, Titania and Oberon, in 1787.
Nigel Mason at the University of Kent in the UK emphasized the excitement of these finds. "Everybody always likes to find new moons and everybody always likes to think about what they’re going to call them," he said. "It’s an exciting moment. It’s a bit of a legacy."
Mason predicts additional moons around Neptune and Uranus, noting that while the largest have likely been cataloged, smaller ones persist. He added that such discoveries go beyond mere collection: "Why are there so many? What is it that triggered [planets] to make 40, 50, 60 of such varying shapes and sizes? That’s why they’re exciting." Cataloging these bodies, he explained, helps update models of planet formation, revealing gaps in current knowledge: "Really surprisingly, the whole planet-formation process is not as well as understood as we think."