Uranus may have a 29th moon

Uranus appears to have yet another moon. Observations made with the James Webb Space Telescope (JWST) detected the presence of this small satellite earlier this year, bringing the ice giant’s number of known satellites up to 29. The data is still making its way through the peer review process for final confirmation, but everything points to a new addition to the family.

The initial indications of an additional moon arrived on February 2, when JWST aimed its Near-Infrared Camera at Uranus for a series of 10, 40-minute-long exposure images. Subsequent analysis appears to confirm the diminutive satellite is part of the intricate system of 14 moons located inward from the larger moons of Ariel, Miranda, Oberon, Titania, and Umbriel. 

“No other planet has as many small inner moons as Uranus, and their complex inter-relationships with the rings hint at a chaotic history that blurs the boundary between a ring system and a system of moons,” SETI Institute researcher Matthew Tiscareno said in a statement for NASA.

Temporarily designated as S/2025 U1, the moon is estimated to be only six-miles-wide. For reference, that’s less-than-a-third the width of New York City. Its solar reflectivity (or albedo) is also substantially less bright than the planet’s similarly small, dim moons. These details likely explain how Voyager 2 missed it when the space probe made its fly-by survey nearly 40 years ago on January 24, 1986. 

According to Southwest Research Institute’s Solar System Science and Exploration Division scientist Maryame El Moutamid, S/2025 U1 is located about 35,000 miles from Uranus’ center. It orbits its equatorial plane between Ophelia and Bianca, just outside the bounds of the planet’s main ring system.

“Its nearly circular orbit suggests it may have formed near its current location,” El Moutamid added.

There isn’t much more available information at the moment,but astronomers think there is still a lot to learn about this latest Uranian moon.

“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,” said Tiscareno.

Uranus’ most recent moon was discovered in 2023 and designated as S/2023 U1. Like its predecessor, this newest known satellite will keep its admittedly dry title of S/2025 U1 for the time being. However, both moons will eventually receive new names once they’re approved by the International Astronomical Union. And if historical precedent is any indication, there is a solid chance they’ll reference characters from the works of either William Shakespeare or Alexander Pope.

 

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