S/2025 U 1 is a small moon of Uranus,[3] with an estimated diameter between 8 and 10 kilometres (5 and 6 miles).[2] 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][b]
 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[1] | |
| 56250±250 km | |
| Eccentricity | ≈ 0 |
| 0.402 d (9.6 h) | |
| Inclination | ≈ 0° |
| Satellite of | Uranus |
| Physical characteristics | |
| 8–10 km (5–6 mi)[1][2] | |
| Albedo | 0.05–0.10 (assumed)[1] |
| 25.5 (H-band) | |
The moon orbits about 56,250 km (34,950 mi) from the center of Uranus (between the orbits of Ophelia and Bianca) with an orbital period of 9.6 hours (0.402 days).[1] 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]
Name
editS/2025 U 1 is the provisional designation of this unnamed moon.[3] By convention, the moons of Uranus are named after characters from the plays of William Shakespeare and Alexander Pope.[2] A proper name will be given once it is approved by the International Astronomical Union.[2][3] 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."[3]
Orbit
edit
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).[2] S/2025 U 1 follows a nearly circular orbit around Uranus's equatorial plane, at a distance of 56,250 km (34,950 mi) from the planet's center with an orbital period of 9.6 hours (0.402 days).[1] S/2025 U 1 is located outside the edge of Uranus's inner ring system, between the orbits of Ophelia and Bianca.[3] The nearly circular orbit of S/2025 U 1 suggests that it formed near its current ___location, according to El Moutamid.[2]
Notes
edit- ^ a b The full team of researchers involved in the discovery of this moon includes: Maryame El Moutamid, Matthew M. Hedman, Mark R. Showalter, Matthew Tiscareno, Imke de Pater, Jack J. Lissauer, and Damya Souami.[1]
- ^ The NIRCam discovery observations consisted of ten consecutive near-infrared images, each with 40-minute-long exposure times.[2]
References
edit- ^ a b c d e f g h i j k Green, Daniel W. E. (19 August 2025). "CBET 5593: S/2025 U 1". Central Bureau Electronic Telegram. Central Bureau for Astronomical Telegrams. Retrieved 19 August 2025.
- ^ a b c d e f g El Moutamid, Maryame (19 August 2025). "New Moon Discovered Orbiting Uranus Using NASA's Webb Telescope". NASA. Retrieved 19 August 2025.
- ^ a b c d e Sparkes, Matthew (19 August 2025). "New moon discovered orbiting Uranus is its smallest one". NewScientist. Archived from the original on 19 August 2025. Retrieved 19 August 2025.
External links
edit- James Webb Space Telescope (JWST) (19 August 2025). "New Moon Discovered Orbiting Uranus Using NASA's Webb Telescope (video)". YouTube.
- El Moutamid, Maryame; et al. (10 September 2025). New JWST Discoveries on the Uranian System. EPSC-DPS Joint Meeting 2025. Vol. 18. Finlandia Hall, Helsinki, Finland. doi:10.5194/epsc-dps2025-421. EPSC-DPS2025-421.
- El Moutamid, Maryame; et al. (12 December 2024). "JWST Proposal 6379 – Structure and Dynamics of The Rings and Inner Moons of Uranus". Space Telescope Science Institute. Cycle 3.