Uranus' natural satellites

Uranus has 27 known moons. The first two moons (Titania and Oberon) were discovered by William Herschel on March 13, 1787. Two more moons (Ariel and Umbriel) were discovered by William Lassell in 1851. In 1852, Herschel's son John Herschel gave the four then-known moons their names. In 1948 Gerard Kuiper discovered the moon Miranda.

The flyby of the Voyager 2 space probe in January 1986 led to the discovery of a further 10 moons, and another satellite Perdita was later found after studying old Voyager photographs. Eleven additional moons have since been identified using telescopes.

Unlike most planetary moons, which are named from antiquity, all the moons of Uranus are named after characters from the works of Shakespeare and Alexander Pope.

The natural satellites

The Uranian moons are listed here by orbital period, from shortest to longest. Moons massive enough for their surfaces to have collapsed into a spheroid are highlighted in light purple. Irregular (captured) moons are shown in light grey.

Notes: * Awaiting confirmation and naming; ** Negative orbital periods indicate a retrograde orbit around Uranus (opposite to the planet's rotation).(Pronunciation respelling key)

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Name (spheroidal moons in bold)			Mean diameter (km)	Mass (kg)	Semi-major axis (km)	Orbital period (day)	Discovery date
Uranus VI	Cordelia	kor-dee'-lee-ə	40 ± 6	4.5?	49,770	0.335034	1986
Uranus VII	Ophelia	oe-fee'-lee-ə	43 ± 8	5.4?	53,790	0.376400	1986
Uranus VIII	Bianca	bee-aang'-kə	51 ± 4	9.3?	59,170	0.434579	1986
Uranus IX	Cressida	kres'-ə-də	80 ± 4	3.43?	61,780	0.463570	1986
Uranus X	Desdemona	dez'-də-moe'-nə	64 ± 8	1.78?	62,680	0.473650	1986
Uranus XI	Juliet	jew'-lee-et'	94 ± 8	5.57?	64,350	0.493065	1986
Uranus XII	Portia	por'-shə	135 ± 8	1.68?	66,090	0.513196	1986
Uranus XIII	Rosalind	roz'-ə-lind	72 ± 12	2.54?	69,940	0.558460	1986
Uranus XXVII	Cupid	kew'-pid	~ 17.8	3.8?	74,800	0.618	2003
Uranus XIV	Belinda	be-lin'-də	81 ± 16	3.57?	75,260	0.623527	1986
Uranus XXV	Perdita	pər'-di-tə	~ 26.6	1.3?	76,420	0.638	1986
Uranus XV	Puck	puk'	162 ± 4	2.89?	86,010	0.761833	1985
Uranus XXVI	Mab	mab'	~ 24.8	1.0?	97,734	0.923	2003
Uranus V	Miranda	mə-ran'-də	471.6 ± 1.4	(6.6 ± 0.7)	129,390	1.413479	1948
Uranus I	Ariel	arr'-ee-əl	1157.8 ± 1.2	(1.35 ± 0.12)	191,020	2.520379	1851
Uranus II	Umbriel	um'-bree-əl	1169.4 ± 5.6	(1.17 ± 0.13)	266,300	4.144177	1851
Uranus III	Titania	ti-taan'-yə	1577.8 ± 3.6	(3.53 ± 0.09)	435,910	8.705872	1787
Uranus IV	Oberon	oe'-bər-on	1522.8 ± 5.2	(3.01 ± 0.07)	583,520	13.463239	1787
Uranus XXII	Francisco	fran-sis'-koe	~ 12	1.3?	4,276,000	-266.6^**	2001
Uranus XVI	Caliban	kal'-ə-ban	~ 98	7.3?	7,231,000	-579.7^**	1997
Uranus XX	Stephano	stef'-ə-noe	~ 20	6?	8,004,000	-677.4^**	1999
Uranus XXI	Trinculo	tring'-kew-loe	~ 10	7.5?	8,504,000	-759.0^**	2001
Uranus XVII	Sycorax	sik'-or-aks	~ 190	5.4?	12,179,000	-1288.3^**	1997
Uranus XXIII	Margaret	mar'-grit	~ 11	1.3?	14,345,000	1694.8	2003
Uranus XVIII	Prospero	pros'-pər-oe	~ 30	2.1?	16,256,000	-1977.3^**	1999
Uranus XIX	Setebos	set'-ə-bus	~ 30	2.1?	17,418,000	-2234.8^**	1999
Uranus XXIV	Ferdinand	fər'-də-nand	~ 12	1.3?	20,901,000	-2823.4^**	2001

Sources: NASA/NSSDC and University of Hawaii. These sources give no information on the masses for the small satellites.

Naming notes

Some asteroids share the same names as moons of Uranus: 171 Ophelia, 218 Bianca, 593 Titania, 666 Desdemona, 763 Cupido and 2758 Cordelia.

External link

NASA's Hubble Discovers New Rings and Moons Around Uranus (STScI-2005-33, December 22, 2005)

Uranus' moons

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The natural satellites

Naming notes

See also

External link