Astronomers using the James Webb Space Telescope (JWST) have identified a new moon orbiting Uranus, raising the planet’s tally to 29 confirmed satellites. The tiny object, temporarily designated S/2025 U1, was first detected on February 2, 2025, during observations aimed at studying Uranus’s rings and atmosphere.
Measuring only about 10 kilometers (6 miles) wide, S/2025 U1 is the smallest moon ever found around Uranus. Its faint size meant that earlier missions, including NASA’s Voyager 2 flyby in 1986, completely missed it.
The discovery came from near-infrared images taken by JWST. Astronomers noticed a faint speck of light moving in sync with Uranus. Further checks confirmed that the object was locked in orbit, rather than a distant star in the background.
This marks another demonstration of JWST’s sharp vision, capable of spotting objects far too dim for previous instruments. While ground-based telescopes have uncovered several Uranian moons in recent years, none have been as small as this.
S/2025 U1 circles the planet just beyond Uranus’s faint rings. Scientists think it is likely made of rock or ice, like its neighbors. With a diameter no larger than a small town, a person could, in theory, walk across its surface in only a few hours. But with no atmosphere and temperatures far below freezing, it is not a place suited for human visitors.
The new moon follows the unusual tilted orbital plane created by Uranus’s sideways rotation, keeping it steady among the planet’s existing satellites.
Most of Uranus’s moons are named after characters from Shakespeare and Alexander Pope. The largest, Titania, spans more than 1,500 kilometers (over 900 miles), while the newly found S/2025 U1 is now the tiniest member of the family.
How these moons formed is still debated. Some may be remnants of ancient impacts, while others could be captured objects from elsewhere in the solar system. More observations will be needed to determine where S/2025 U1 fits in.
Even at this size, the moon could play an important role. Its gravity might help maintain the structure of Uranus’s faint rings, keeping them from spreading apart. Studying these interactions could offer clues about the planet’s past collisions and its present dynamics.
Uranus is still one of the least explored planets, with no dedicated missions since Voyager 2’s brief visit nearly four decades ago. Scientists say this discovery adds weight to calls for a future probe to orbit the planet and study its complex system in detail.
For now, S/2025 U1 stands as proof that our solar system still holds surprises and that new technology is key to uncovering them.
Source: New Moon Discovered Orbiting Uranus Using NASA’s Webb Telescope