New moon found orbiting inside distant Uranus’ rings

This story was originally published by the NASA Webb Mission Team. Edits by EarthSky.

Editor’s be aware: This put up highlights information from Webb science in progress, which has not but been by the peer-review course of.

• A brand new tiny moon orbiting Uranus was recognized in February 2025 utilizing the James Webb Space Telescope’s Near-Infrared Camera. The staff captured a collection of ten 40-minute exposures to detect it.
• Extremely small and faint, the moon measures solely about 6 miles (~10 km) throughout. It is just too dim for Voyager 2 or the Hubble Space Telescope to detect.
• This brings Uranus’s identified moons to 29, expands understanding of its inside moon system and hints that much more such small satellites could await discovery.

Voyager 2, Hubble missed this tiny new moon

Using NASA’s James Webb Space Telescope, a staff led by the Southwest Research Institute has recognized a beforehand unknown moon orbiting Uranus. This expands the planet’s identified satellite tv for pc household to 29. The detection was made throughout a Webb statement on February 2, 2025.

Maryame El Moutamid, a lead scientist on the Southwest Research Institute and principal investigator on Webb observing program 6379 to review the rings and moons of Uranus, described the invention:

This object was noticed in a collection of 10 40-minute long-exposure pictures captured by the Near-Infrared Camera. It’s a small moon however a big discovery, which is one thing that even NASA’s Voyager 2 spacecraft didn’t see throughout its flyby practically 40 years in the past.

New moon at the moment named S/2025 U1

The time-lapse animation (embedded above) reveals the newly found moon of Uranus, designated S/2025 U1. It additionally reveals 13 of the 28 different identified moons orbiting the planet. The observations by NASA’s James Webb Space Telescope’s Near-Infrared Camera had been taken over the course of about six hours on February 2, 2025, below program ID 6379. The animation is comprised of knowledge taken with the Near Infrared Camera’s broad band F150W2 filter, which transmits infrared wavelengths from about 1.0 to 2.4 microns. Also, because of the drastic variations in brightness ranges, the animation is a composite of three totally different remedies of the info. This permits the viewer to see particulars within the planetary ambiance, the encompassing rings and the orbiting moons.

The newly found moon is estimated to be simply 6 miles (10 kilometers) in diameter. This assumes it has the same reflectivity (albedo) to Uranus’ different small satellites. In reality, that tiny measurement probably rendered it invisible to Voyager 2, a NASA probe launched in 1977, and different telescopes.

Matthew Tiscareno of the SETI Institute and a member of the analysis staff described the invention’s significance:

No different planet has as many small inside moons as Uranus, and their complicated interrelationships with the rings trace at a chaotic historical past that blurs the boundary between a hoop system and a system of moons. Moreover, the brand new moon is smaller and far fainter than the smallest of the beforehand identified inside moons, making it probably that much more complexity stays to be found.

New moon orbits on the fringe of Uranus’ essential ring system

The picture launched by the analysis staff is a fancy one. At middle is the planet Uranus, a blue globe with a big white spot occupying a lot of the planet. It’s surrounded by a collection of rings that get brighter as you progress outward. Then, past the rings are 14 labeled moons showing as factors of sunshine. Finally, simply on the fringe of the outermost seen ring at 10 o’clock, a faint moon is circled and labeled S 2025 U1.

At far left, the brightest moon is labeled Miranda. In addition, different moons clockwise from Miranda are Puck, Cressida, Mab, Perdita, Desdemona, Belinda, Bianca, Ophelia, Rosalind, Portia, Cupid and Juliet.

The moon Cordelia, found by Voyager 2 in 1986, orbits simply contained in the outermost ring, however is just not seen in these views as a result of glare from the rings. Because of these drastic variations in brightness ranges, the picture is a composite of three totally different remedies of the info, permitting the viewer to see particulars within the planetary ambiance, the encompassing rings and the orbiting moons. The information was taken with the Near-Infrared Camera’s broad band F150W2 filter, which transmits infrared wavelengths from about 1.0 to 2.4 microns.

Tiny moon has an almost round orbit

The new moon is the 14th member of the intricate system of small moons orbiting inward of the most important moons Miranda, Ariel, Umbriel, Titania and Oberon.

All the moons of Uranus are named after characters in works of the English writers William Shakespeare and Alexander Pope.

El Moutamid described the way it suits into the system:

It’s positioned about 35,000 miles (56,300 kilometers) from Uranus’ middle, orbiting the planet’s equatorial aircraft between the orbits of Ophelia – which is simply exterior of Uranus’ essential ring system – and Bianca. Its practically round orbit suggests it might have fashioned close to its present location.

A reputation for the newly discovered moon will must be authorised by the International Astronomical Union, the main authority in assigning official names and designations to astronomical objects.

Discovery continues historical custom of human exploration

El Moutamid stated the Webb telescope performed a important position in discovering the brand new moon:

Through this and different packages, Webb is offering a brand new eye on the outer photo voltaic system. This discovery comes as a part of Webb’s General Observer program, which permits scientists worldwide to suggest investigations utilizing the telescope’s cutting-edge devices. The NIRCam instrument’s excessive decision and infrared sensitivity make it particularly adept at detecting faint, distant objects that had been past the attain of earlier observatories.

She additionally stated discovering the brand new moon at Uranus continues the historical past of humanity’s ongoing exploration of our photo voltaic system:

Looking ahead, the invention of this moon underscores how trendy astronomy continues to construct upon the legacy of missions like Voyager 2, which flew previous Uranus on January 24, 1986, and gave humanity its first close-up have a look at this mysterious world. Now, practically 4 many years later, the James Webb Space Telescope is pushing that frontier even farther.

Bottom line: Astronomers have found a twenty ninth moon orbiting Uranus. The newly discovered moon is 6 miles (10 kilometers) broad.

Read extra: Oceans for 4 Uranus moons probably, astronomers say