NASA’s James Webb Space Telescope has uncovered a previously unknown moon orbiting Uranus, raising the planet’s tally to 29. The discovery, led by scientists from the Southwest Research Institute (SwRI), adds a new piece to the puzzle of Uranus’ intricate satellite system.

The faint object was detected on February 2 using Webb’s Near-Infrared Camera (NIRCam), appearing in a sequence of ten long-exposure images.

Figure 1. Webb Telescope Spots Uranus.

“This moon was spotted across a series of 40-minute exposures captured by NIRCam,” explained Maryame El Moutamid, lead scientist at SwRI’s Solar System Science and Exploration Division in Boulder, Colorado. “Although it’s small, it’s a remarkable find—something even Voyager 2 missed during its historic flyby almost 40 years ago.” Figure 1 shows Webb Telescope Spots Uranus.

Based on brightness comparisons with Uranus’ other small moons, researchers estimate the new satellite to be just six miles (10 kilometers) across. Its diminutive size likely kept it hidden from Voyager 2 and ground-based telescopes.

A crowded inner system

The new addition further complicates Uranus’ unusually dense collection of inner moons. “No other planet has as many small inner satellites as Uranus,” said Matthew Tiscareno of the SETI Institute, a member of the research team. “Their interactions with the rings hint at a chaotic past that blurs the line between a moon system and a ring system.”

This newly spotted body is even smaller and fainter than Uranus’ faintest known inner moons, suggesting the planet’s satellite network may be more complex than previously thought. It becomes the 14th known object orbiting inside Uranus’ five major moons—Miranda, Ariel, Umbriel, Titania, and Oberon. In keeping with tradition, the International Astronomical Union (IAU) will later assign it an official name.

Orbit and origin

Calculations show the moon circles Uranus at about 35,000 miles (56,000 kilometers) from the planet’s center, between the orbits of Ophelia and Bianca. Its nearly circular path suggests it likely formed close to its current location.

The find underscores the power of Webb’s infrared instruments, which can reveal faint and distant objects that earlier missions and observatories could not. With this discovery, Uranus’ mysterious system of moons and rings has become even more intriguing.

Reference:

1. https://interestingengineering.com/space/uranus-29th-moon-webb-discovery

Cite this article:

Keerthana S (2025), Webb Telescope Spots Uranus’ 29th Moon Missed by Voyager 2 Nearly 40 Years Ago, AnaTechMaz, pp.541