Decrease font size Increase font size Print this page Français

Encyclopédie > Numbers about the solar system XI

 

Orbital elements of satellites: URANUS



The planet Uranus has rings and three families of satellites, orbiting around it (27 satellites, all numbered on December 3, 2022):

  • the rings were discovered in 1977 during the Earth-based observation of an occultation of a star by the planet Uranus and are directly observable from Earth only in the infrared wavelengths.
  • the inner satellites: these satellites are orbiting inside the orbit of Miranda, the first main satellite. Because of the closeness of the planet, they are very difficult to observe. Infrared observations are necessary in order to decrease the contrast brightness between the planet and the satellites.
  • the main satellites: these satellites, similar to small planets, are bright and easily observable even in a telescope except Miranda which is the closer and the fainter main satellite.
  • the outer irregular satellites: these satellites are orbiting outside the orbit of Oberon, the farthest main satellite. They are very faint due to their small sizes and their orbits are neither circular, nor in the equatorial plane of Uranus as the inner and the main satellites. They are observable as asteroids, independantly of the planet Uranus far from them. Only their faintness is a difficulty for their observation.

The tables below provide the main characteristics of these satellites including orbital parameters. These data may change either because new data are more precise, or because some parameters are evoluting year after year. The year of the discovery is provided by the provisional name of the satellite. For some satellites, specific descriptive pages are available.



The rings


Rings and inner satellites    Distance to the 
center of Uranus  		   Size of the ring   Thickness   Albedo  
zeta ζ (1986 U2R) 38 000 km 2 500 km 100 m 0.03
ring 6 41 840 km 1 to 3 km 100 m 0.03
ring 5 42 230 km 2 to 3 km 100 m 0.03
ring 4 42 580 km 2 to 3 km 100 m 0.03
alpha α 44 720 km 7 to 12 km 100 m 0.03
beta β 45 670 km 7 to 12 km 100 m 0.03
heta η 47 190 km 0 to 2 km 100 m 0.03
gamma γ 47 630 km 1 to 4 km 100 m 0.03
delta δ 48 290 km 3 to 9 km 100 m 0.03
satellite Cordelia (U-6) 49 752 km - - -
1986 U1R 50 020 km 1 to 2 km 100 m 0.03
epsilon ε
("shepherd" by U-6 and U-7)		 51 140 km 20 to 100 km less than 150 m 0.03
satellite Ophelia (U-7) 53 764 km - - -
 


The inner satellites


 
 satellites 
 		 a in km     P in days     eccentricity     inclination on the equator of Uranus     d in km     mv     ap in arcsec     discovery  
Cordelia - U 6 49 752 0.335 0.00047 0.14° 26 24.2 4.0 1986 U7
Ophelia - U 7 53 764 0.376 0.0101 0.09° 30 23.9 4.3 1986 U8
Bianca - U 8 59 165 0.435 0.00088 0.16° 42 23.1 4.7 1986 U9
Cressida - U 9 61 767 0.464 0.00023 0.04° 62 22.3 4.9 1986 U3
Desdemone - U 10 62 659 0.474 0.000 23 0.16° 54 22.5 5.0 1986 U6
Juliet - U 11 64 358 0.493 0.000 59 0.06° 84 21.7 5.1 1986 U2
 Portia - U 12 66 097 0.513 0.000 17 0.09° 108 21.1 5.3 1986 U1
Rosalinde - U 13 69 927 0.558 0.000 09 0.28° 54 22.5 5.6 1980 U6
Cupid - U 27 74 800 0.616 0.0 ? ? ? 5.9 2003 U2
Belinda - U 14 75 255 0.624 0.000 11 0.03° 66 22.1 6.0 1986 U5
Perdita - U 25 76 420 0.638 0.0 0.0° 20 24.0 6.1 1986 U10
Puck - U 15 86 004 0.762 0.000 05 0.31° 154 20.4 6.7 1985 U1
Mab - U 26 97 734 0.923 ? ? ? ? 7.5 2003 U1
a=semi-major axis; P= period of revolution; d=diameter; mv= visual magnitude at opposition; ap= maximal apparent distance to Uranus at opposition


The main satellites


  Miranda - U 5 Ariel - U 1 Umbriel - U 2 Titania - U 3 Oberon - U 4
semi-major axis in km 129 872 190 945 265 998 436 298 583 519
period of revolution 1.413 479 d 2.520 379 d 4.144 176 d 8.705 867 d 13.463 234 d
eccentricity 0.0013 0.0012 0.0040 0.0014 0.0016
inclination on the equator of Uranus 4.34 ° 0.04 ° 0.13 ° 0.08° 0.07°
size in km 480.8 x 468.4 x 465.8 1162.2 x 1155.8 x 1155.4 1169.4 1577.8 1522.8
magnitude at opposition 16.5 14.4 15.3 13.9 14.2
maximal apparent distance to Uranus at opposition  10 arcsec  15  arcsec  21  arcsec  35  arcsec 47 arcsec
 
the given size corresponds to: equatorial sub-planetary diameter , equatorial diameter along the orbit and polar diameter of the triaxial ellipsoid


 

The outer irregular satellites


 
 satellites 
 		 a in km     P in days     eccentricity     inclination on the ecliptic     d in km     mv     ap in arcmin     discovery  
Francisco - U 22 4 276 000 266.6 0.146 145.2° 22 25.0 5.2 2001 U3
Caliban - U 16 7 170 000 579.6 0.159 139.8° 60 22.4 9.5 1997 U1
Stephano - U 20 7 942 000 675.7 0.229 141.5° 32 24.1 10.5 1999 U2
Trinculo - U 21 8 571 015 759.7 0.220 166.3° 18 25.1 11.4 2001 U1
Sycorax - U 17 12 216 000 1289.0 0.522 152.7° 150 20.8 16.2 1997 U2
Margaret - U 23 14 345 000 1694.8 0.661 56.6° 20 25.2 18.7 2003 U3
Prospero - U 18 16 089 000 1948.1 0.445 146.3° 50 23.2 21.4 1999 U3
Setebos - U 19 17 988 000 2303.1 0.591 148.3° 47 23.3 23.9 1999 U1
Ferdinand - U 24 20 901 000 2823.4 0.368 169.8° 21 25.1 25.4 2001 U2
a=semi-major axis; P= period of revolution; d=diameter; mv= visual magnitude at opposition; ap= maximal apparent distance to Uranus at opposition