New Moon Discovered Orbiting Uranus by James Webb Space Telescope

Updated on: August 19, 2025 | By: Jameswebb Discovery Editorial Team

James Webb Telescope Discovers Tiny New Moon Orbiting Uranus: S/2025 U1 Reveals Hidden Secrets

On February 2, 2025, astronomers using the NASA James Webb Space Telescope (JWST) made a groundbreaking discovery in the outer solar system: a previously unknown moon orbiting Uranus. Designated S/2025 U1, this tiny satellite measures only six miles across, making it one of the smallest moons ever observed. Its detection not only raises Uranus’ total moons to 29 but also demonstrates Webb’s unprecedented ability to uncover faint, distant objects that even the Voyager 2 spacecraft missed nearly 40 years ago.

With Webb’s Near-Infrared Camera (NIRCam) capturing long-exposure images in infrared light, scientists were able to reveal S/2025 U1 amid Uranus’ complex ring system and intricate network of moons. This discovery offers a new glimpse into the planet’s hidden inner world and hints at the possibility of even more undiscovered moons. 

Meet S/2025 U1: Uranus’ Newly Discovered Tiny Moon

S/2025 U1 orbits Uranus at a distance of approximately 35,000 miles (56,000 kilometers) from the planet’s center, positioned between the orbits of the inner moons Ophelia and Bianca. Its nearly circular orbit suggests that it likely formed near its current location rather than being captured from elsewhere in the solar system. Despite its small size, this moon provides a critical piece of the puzzle in understanding Uranus’ inner moon system.

The discovery of such a faint object was only possible because of Webb’s exceptional infrared sensitivity and high-resolution imaging. By combining multiple long-exposure frames, astronomers could isolate the dim light of S/2025 U1 from Uranus’ bright atmosphere and surrounding rings, revealing details that were invisible to both Voyager 2 and Earth-based telescopes.

Why This Uranus Moon Discovery Changes Everything

Uranus’ system of small inner moons is unparalleled in the solar system. Unlike the larger moons—Miranda, Ariel, Umbriel, Titania, and Oberon—these inner moons interact dynamically with Uranus’ rings, creating a chaotic and fascinating environment. According to astronomer Matthew Tiscareno of the SETI Institute, “The new moon is smaller and much fainter than the smallest of the previously known inner moons, making it likely that even more complexity remains to be discovered.”

This discovery emphasizes that Uranus’ inner region is still largely unexplored. Each new moon, no matter how tiny, provides valuable clues about the planet’s history, the evolution of its rings, and the formation of its satellite system.

How James Webb Telescope Revealed What Voyager 2 Couldn’t

The James Webb Space Telescope is transforming our view of the outer solar system. Its Near-Infrared Camera (NIRCam), using the wide-band F150W2 filter that captures light between 1.0 and 2.4 microns, is capable of detecting faint celestial bodies that escaped all previous searches.

The images of Uranus were processed using three different treatments to balance the extreme differences in brightness between the planet, its rings, and its moons. This composite method allows viewers to see the planet’s atmosphere, its faint ring system, and the 14 moons visible in the observation, including the newly discovered S/2025 U1.

Nearly forty years after Voyager 2 flew past Uranus in 1986, Webb’s observations reveal details that were previously unimaginable. This reinforces the telescope’s role as a powerful tool for planetary science, continuing the legacy of earlier missions while dramatically expanding our knowledge.

Inside Uranus’ Mysterious Ring and Moon System

Before this discovery, Uranus had 28 confirmed moons, all named after characters from Shakespeare and Alexander Pope. With S/2025 U1, Uranus now has 29 known moons. The inner moon system, where S/2025 U1 resides, is unique because it blurs the line between rings and satellites. The tiny moons interact gravitationally with the rings, creating a delicate and dynamic balance that is still being studied by astronomers.

The discovery of S/2025 U1 also provides a perfect opportunity for readers to explore more about Uranus’ fascinating features. For a deeper dive into the planet’s rings, moons, and unique characteristics, check out our article on 100 Interesting Facts About Uranus.

What’s Next for S/2025 U1 and Uranus Exploration

The newly discovered moon will need an official name approved by the International Astronomical Union (IAU). Following tradition, it is likely to be named after a Shakespearean character. Scientists will continue to analyze Webb’s images, searching for additional small moons and studying the complex interactions between Uranus’ moons and rings.

As Webb continues its mission, astronomers expect more discoveries that will deepen our understanding of Uranus’ inner environment. S/2025 U1, though only six miles wide, represents a major leap forward in our knowledge of the outer solar system, proving that even the smallest moons can reveal huge insights about planetary formation and evolution.

Conclusion

The discovery of S/2025 U1 demonstrates once again that the James Webb Space Telescope is reshaping our understanding of the solar system. Nearly four decades after Voyager 2 first revealed Uranus’ larger moons, Webb has uncovered a hidden moon that adds complexity to the planet’s rings and inner satellites.

This tiny moon underscores the importance of continued exploration with advanced telescopes. Each new discovery brings us closer to understanding the mysterious world of Uranus and the outer reaches of our solar system, where even the smallest objects can tell big stories.