![]() Discovery image of S/2025 U 1 (circled) by the James Webb Space Telescope on 2 February 2025 | |
Discovery [1] | |
---|---|
Discovered by | Maryame El Moutamid et al. [a] |
Discovery site | James Webb Space Telescope |
Discovery date | 2 February 2025 (date of discovery images) [1] |
Orbital characteristics [2] | |
Epoch 1 January 2025 TDB | |
57844 km | |
Eccentricity | 0.039 |
0.4021 d (9.65 h) | |
275.6° | |
Inclination | 4.0° (wrt local Laplace plane [b] ) |
70.8° | |
313.9° | |
Satellite of | Uranus |
Physical characteristics | |
8–10 km (5–6 mi) [1] [3] | |
Albedo | 0.05–0.10 (assumed) [1] |
25.5 (H-band) | |
S/2025 U 1 is a small moon of Uranus, with an estimated diameter between 8 and 10 kilometres (5 and 6 miles). [3] It was the 29th moon identified in the Uranus system. The discovery was announced in August 2025 by a team of astronomers led by Maryame El Moutamid, [a] who found the moon in James Webb Space Telescope NIRCam images taken on 2 February 2025. [1] [c]
The moon orbits about 57,844 km (35,943 mi) from the center of Uranus (between the orbits of Ophelia and Bianca) with an orbital period of 9.6 hours (0.402 days). [2] Like the other inner moons of Uranus, it follows a nearly circular orbit along Uranus's equatorial plane. [1] Due to its small size, it appears extremely faint with a near-infrared (H-band) apparent magnitude of 25.5—too faint to be seen by the Hubble Space Telescope and the Voyager 2 spacecraft. [1]
S/2025 U 1 is the provisional designation of this unnamed moon. [4] By convention, the moons of Uranus are named after characters from the plays of William Shakespeare and Alexander Pope. [3] A proper name will be given once it is approved by the International Astronomical Union. [3] [4] Co-discoverer Mark R. Showalter has stated in a 2025 New Scientist article that "there have been discussions [of a name for S/2025 U 1] but no shortlist as yet." [4]
S/2025 U 1 is the 14th known member of Uranus's inner moons, which are small moons that orbit interior to the planet's five largest moons (Miranda, Ariel, Umbriel, Titania, and Oberon). [3] S/2025 U 1 follows a nearly circular orbit around Uranus's equatorial plane, at a distance of 57,844 km (35,943 mi) from the planet's center with an orbital period of 9.6 hours (0.402 days). [2] S/2025 U 1 is located outside the edge of Uranus's inner ring system, between the orbits of Ophelia and Bianca. [4] The nearly circular orbit of S/2025 U 1 suggests that it formed near its current location, according to El Moutamid. [3]