415:
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512:. The moons of the Caliban group have orbital elements that are clustered with semi-major axes between 7–8 million km (4.3–5.0 million mi), eccentricities between 0.16 and 0.23, and inclinations between 141° and 144°. Like all other irregular moon groups, the Caliban group is thought to have formed from the destruction of a larger captured moon of Uranus due to asteroid and comet
493:, meaning it orbits in the opposite direction of Uranus' orbit around the Sun. Due to perturbations, S/2023 U 1's orbital elements fluctuate over time: its semi-major axis can range from 7.97 to 7.98 million km (4.95 to 4.96 million mi), eccentricity from 0.14 to 0.29, and inclination from 141° to 144°. S/2023 U 1's orbit exhibits
397:
To plan follow-up observations of S/2023 U 1, Sheppard collaborated with Marina
Brozović and Robert Jacobson to calculate predictions for the moon's orbit and positions on other dates. Sheppard observed S/2023 U 1 with the Magellan Telescope on 6 and 13 December 2023, and was able to trace the moon
908:
389:
telescope images, aligned and shifted them to follow Uranus's motion, and then added them together to create a single deep image that would show
Uranian moons as points of light against trailed background stars and galaxies. Applying the shift-and-add technique to very large
540:
range of 0.04–0.10 that is typical for most irregular moons, S/2023 U 1 has a diameter between 8–12 km (5–7 mi). Sheppard estimates the diameter to be 8 km, which if correct would make S/2023 U 1 the smallest known satellite orbiting Uranus.
620:
466:
are used to describe the long-term orbits of irregular moons more accurately, since these are calculated by averaging out the perturbed orbit over a long period of time.
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402:
on 23 February 2024, bringing Uranus's number of known moons from 27 to 28. It is the first
Uranian moon discovered in the over 20 years since the discovery of
458:
by the gravity of the Sun and other planets. This results in significant changes in the orbits of irregular moons over short periods of time, so a simple
1772:
1034:
438:. The relative sizes of moons are indicated by the size of their symbols, and the Caliban group of Uranian moons is labeled. Data as of February 2024.
418:
Irregular satellites of
Jupiter (red), Saturn (green), Uranus (magenta) and Neptune (blue; including Triton), plotted by distance from their planet (
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direction at an average distance of about 8 million km (5 million mi) and takes almost 2 Earth years to complete its orbit.
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orbit. Irregular moons are loosely bound by Uranus's gravity because of their great distance from the planet, so their orbits are frequently
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S/2023 U 1 was discovered on 4 November 2023 by Scott S. Sheppard during his search for
Uranian irregular moons with the 6.5-m
259:
147:
1762:
1027:
473:
or orbital distance from Uranus is 7.98 million km (4.96 million mi; 0.0533 AU), with an average
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back to his earlier observations on 8 September and 2 December 2021. S/2023 U 1 was confirmed and announced by the
44:
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telescopes like the
Magellan Telescope. Nothing is known about S/2023 U 1's physical properties other than its
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Sharkey, Benjamin N. L.; Reddy, Vishnu; Kuhn, Olga; Sanchez, Juan A.; Bottke, William F. (November 2023).
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S/2023 U 1 is part of the
Caliban group, a cluster of retrograde irregular moons of Uranus that includes
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telescopes like
Magellan enabled Sheppard to probe deeper than previous Uranian irregular moon surveys.
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known, with a diameter of around 8–12 km (5–7 mi). It was discovered on 4 November 2023 by
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909:"JPL Horizons On-Line Ephemeris for 2023U1 Osculating Orbit (1600-Feb-01 to 2399-Dec-01)"
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cannot accurately describe the long-term orbital motions of irregular moons. Instead,
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622:. Given H = 13.7 and assuming an albedo range of 0.04–0.10, the diameter range is
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of 26.7, so it could only be observed with long-exposure imaging by large-
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939:"Spectroscopic Links among Giant Planet Irregular Satellites and Trojans"
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of 13.7, which can be used to estimate the moon's diameter. Assuming a
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Over an 800-year time span from 1600 to 2400, S/2023 U 1's average
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Ephemeris Type: Elements. Center: 500@7 (Uranus
Barycenter).
615:{\displaystyle D={\frac {1329}{\sqrt {p}}}\times 10^{-0.2H}}
861:"Orbits of the Irregular Satellites of Uranus and Neptune"
381:. Sheppard was able to detect this faint moon through the
1387:
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with an average period of about 5,000 Earth years and
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of 1.86 years (681 d). S/2023 U 1 has an average
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837:. Carnegie Institution for Science. 23 February 2024
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859:Brozović, Marina; Jacobson, Robert A. (May 2022).
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687:"Planetary Satellite Discovery Circumstances"
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1000:Sheppard, Scott S. (23 February 2024).
667:. Minor Planet Center. 23 February 2024
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20:
914:JPL Horizons On-Line Ephemeris System
7:
1002:"New Uranus and Neptune Moon Images"
750:Center for Near Earth Object Studies
1008:. Carnegie Institution for Science.
720:"Planetary Satellite Mean Elements"
794:. Carnegie Institution for Science
661:"MPEC 2024-D113 : S/2023 U 1"
14:
665:Minor Planet Electronic Circulars
153:7,976,600 km (0.053320
1773:Discoveries by Scott S. Sheppard
1727:
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1006:Earth & Planetary Laboratory
835:Earth & Planetary Laboratory
464:proper or mean orbital elements
831:"New Uranus and Neptune Moons"
792:Earth & Planets Laboratory
1:
1778:Moons with a retrograde orbit
1553:Uranus-crossing minor planets
943:The Planetary Science Journal
568:(p) according to the formula
422:) in the horizontal axis and
385:, in which he took many long-
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485:of 144° with respect to the
917:. Jet Propulsion Laboratory
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460:Keplerian elliptical orbit
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746:"Asteroid Size Estimator"
724:JPL Solar System Dynamics
691:JPL Solar System Dynamics
508:and the group's namesake
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1689:Uranus Orbiter and Probe
886:10.3847/1538-3881/ac617f
865:The Astronomical Journal
520:Physical characteristics
375:Las Campanas Observatory
371:Magellan–Baade Telescope
351:Las Campanas Observatory
347:Magellan–Baade Telescope
312:Absolute magnitude
277:Physical characteristics
481:of 0.25 and an average
383:shift-and-add technique
258:Precession of the
139:Proper orbital elements
65:Orbital characteristics
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1763:Irregular satellites
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479:orbital eccentricity
345:using the 6.5-meter
16:Outer moon of Uranus
1603:(472651) 2015 DB216
1275:Geological features
965:2023PSJ.....4..223S
877:2022AJ....163..241B
786:Sheppard, Scott S.
424:orbital inclination
400:Minor Planet Center
260:ascending node
56:Discovery date
45:Discovery site
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974:10.3847/PSJ/ad0845
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442:S/2023 U 1 is an
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114:Satellite of
50:Las Campanas Obs.
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108:8 September 2021
74:1 January 2020 (
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1636:(1986 flyby)
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1304:Verona Rupes
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669:. Retrieved
664:
624:8–12 km
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290:8–12 km
269: /
249: /
207: /
168:eccentricity
18:
1617:Exploration
1563:Co-orbitals
1471:Major moons
841:23 February
798:23 February
756:23 February
730:28 February
697:23 February
671:23 February
483:inclination
428:Hill sphere
198:mean motion
186:143.9° (to
181:inclination
1747:Categories
1446:Atmosphere
1360:Umbrielian
1237:S/2023 U 1
1215:Retrograde
956:2310.19934
949:(11): 20.
634:References
448:elliptical
359:retrograde
331:S/2023 U 1
240:perihelion
78:2458849.5)
22:S/2023 U 1
1663:Proposals
1652:Tianwen-4
1633:Voyager 2
1515:Discovery
1508:Astronomy
1456:Dark Spot
1439:Geography
1311:Oberonian
1299:Mirandian
1262:Ferdinand
1222:Francisco
1097:Desdemona
983:264819644
895:248458067
871:(5): 12.
602:−
594:×
456:perturbed
434:from the
406:in 2003.
365:Discovery
228:(680.776
103:precovery
101:Earliest
27:Discovery
1732:Category
1338:Gertrude
1333:Titanian
1282:Arielian
1252:Prospero
1242:Trinculo
1232:Stephano
1206:Margaret
1199:Prograde
1112:Rosalind
1092:Cressida
1077:Cordelia
564:(H) and
530:aperture
506:Stephano
487:ecliptic
452:inclined
436:ecliptic
404:Margaret
392:aperture
387:exposure
223:1.86386
188:ecliptic
1714:Fiction
1707:Related
1676:OCEANUS
1587:2014 YX
1577:2011 QF
1571:Trojans
1546:General
1494:Titania
1489:Umbriel
1479:Miranda
1451:Climate
1430:Outline
1328:Puckian
1292:Yangoor
1257:Setebos
1247:Sycorax
1227:Caliban
1175:Titania
1168:Umbriel
1154:Miranda
1127:Perdita
1122:Belinda
1082:Ophelia
961:Bibcode
921:1 March
873:Bibcode
514:impacts
510:Caliban
432:degrees
216:Proper
196:Proper
179:Proper
166:Proper
157:)
146:Proper
131:Caliban
1683:ODINUS
1655:(2029)
1644:Future
1499:Oberon
1419:Uranus
1348:Ursula
1316:Hamlet
1182:Oberon
1107:Portia
1102:Juliet
1087:Bianca
1056:Uranus
985:. 223.
981:
897:. 241.
893:
752:. NASA
726:. NASA
693:. NASA
339:Uranus
267:arcsec
247:arcsec
119:Uranus
1484:Ariel
1461:Rings
1375:Skynd
1370:Vuver
1365:Wunda
1161:Ariel
1117:Cupid
1065:Inner
979:S2CID
951:arXiv
891:S2CID
545:Notes
410:Orbit
379:Chile
355:Chile
173:0.250
133:group
126:Group
92:(826
88:2.26
72:Epoch
1670:MUSE
1625:Past
1132:Puck
923:2024
843:2024
800:2024
758:2024
732:2024
699:2024
673:2024
584:1329
450:and
320:13.7
293:8 km
105:date
1137:Mab
969:doi
881:doi
869:163
605:0.2
373:at
349:at
337:of
314:(H)
205:deg
1749::
1589:49
1579:99
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851:^
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642:^
598:10
553:^
377:,
353:,
271:yr
251:yr
225:yr
209:yr
159:AU
155:AU
90:yr
76:JD
1411:e
1404:t
1397:v
1036:e
1029:t
1022:v
971::
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953::
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883::
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760:.
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675:.
626:.
608:H
588:p
579:=
576:D
232:)
230:d
190:)
96:)
94:d
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