Belinda (moon)

Belinda is an inner satellite of the planet Uranus. Belinda was discovered from the images taken by Voyager 2 on 13 January 1986 and was given the temporary designation S/1986 U 5.^[7] It is named after the heroine of Alexander Pope's The Rape of the Lock. It is also designated Uranus XIV.^[8]

Belinda

Belinda viewed by Voyager 2 in 1986
Discovery
Discovered by	Stephen P. Synnott / Voyager 2
Discovery date	January 13, 1986
Designations
Designation	Uranus XIV
Pronunciation	/bəˈlɪndə/[1]
Adjectives	Belindian
Orbital characteristics[2]
Semi-major axis	75 255.613 ± 0.057 km
Eccentricity	0.00007 ± 0.000073
Orbital period (sidereal)	0.623527470 ± 0.000000017 d
Inclination	0.03063 ± 0.028° (to Uranus's equator)
Satellite of	Uranus
Physical characteristics
Dimensions	128 × 64 × 64 km[3][note 1]
Surface area	22000 km2[a]
Volume	270000 km3[b]
Mass	(1.4–3.3)×1017 kg[a]
Mean density	0.5[4]–1.2[4][5] g/cm3
Surface gravity	0.002–0.022 m/s2[c]
Escape velocity	0.017–0.037 km/s[d]
Synodic rotation period	synchronous[3]
Axial tilt	zero[3]
Albedo	0.08 ± 0.01[6]
Temperature	~64 K[a]
Only two dimensions are known; the third dimension has been assumed to equal the smaller known dimension.

Belinda belongs to the Portia group of satellites, which also includes Bianca, Cressida, Desdemona, Portia, Juliet, Cupid, Rosalind, and Perdita.^[6] These satellites have similar orbits and photometric properties.^[6] Other than its orbit,^[2] size of 128 × 64 km,^[3] and geometric albedo of 0.08,^[6] little is known about it.

Voyager 2 images show Belinda as an elongated object with its major axis pointing towards Uranus. The moon is very elongated, with its short axis 0.5 ± 0.1 times the long axis.^[3] Its surface is grey in color.^[3]

Belinda is in a stable 44:43 mean-motion resonance with Perdita, and from this its mass has been determined to be roughly 26^[9] or 27^[5] times that of Perdita.

The inner moon system is unstable over timescales of several millions of years. Belinda and Cupid will probably be the first pair of moons to collide, in 100,000 to 10 million years' time depending on the densities of the Portia-group satellites, due to resonant interactions with the much smaller Cupid.^[4]

See also

• Moons of Uranus

Notes

1. Calculated on the basis of other parameters.
2. Volume derived from the long axis A, the medium axis B and the short axis C: ${\displaystyle {\frac {\pi }{6}}ABC}$
3. Surface gravity derived from the mass m, the gravitational constant G and the radius r: ${\displaystyle {\frac {Gm}{r^{2}}}}$
4. Escape velocity derived from the mass m, the gravitational constant G and the radius r: ${\displaystyle {\sqrt {\frac {2Gm}{r}}}}$