Prospero (moon)

Prospero is a small retrograde irregular satellite of Uranus discovered on 18 July 1999 by the astrophysicist Matthew Holman and his team, and given the provisional designation S/1999 U 3. Confirmed as Uranus XVIII it was named after the sorcerer Prospero in William Shakespeare's play The Tempest.

Animation of discovery images to show Prospero's motion among background stars

Prospero

Discovery image of Prospero, taken by the CFHT in July 1999
Discovery
Discovered by	John J. Kavelaars Brett J. Gladman Matthew J. Holman Jean-Marc Petit Hans Scholl
Discovery date	18 July 1999
Designations
Designation	Uranus XVIII
Pronunciation	/ˈprɒspɛroʊ/[1]
Adjectives	Prosperonian /prɒspɛˈroʊniən/,[2] Prosperian /prɒˈspɪəriən/[3]
Orbital characteristics
Mean orbit radius	16,256,000 km[4][5]
Eccentricity	0.4448[5]
Orbital period (sidereal)	1978.29 d
Inclination	152°[4] (to the ecliptic)[4]
Satellite of	Uranus
Physical characteristics
Mean radius	25 km (estimate)[6] <50 km[7]
Surface area	~8000 km2 (estimate)
Volume	~65,000 km3 (estimate)
Mass	~8.5×1016 kg (estimate)
Mean density	~1.3 g/cm3 (assumed)
Surface gravity	~0.0063 m/s2 (estimate)
Escape velocity	~0.021 km/s (estimate)
Synodic rotation period	7.145±0.092 h[7]
Axial tilt	?
Albedo	0.04 (assumed)[6]
Temperature	~65 K (estimate)

The orbital parameters suggest that it may belong to the same dynamic cluster as Sycorax and Setebos, suggesting a common origin.^[8] However, this suggestion does not appear to be supported by the observed colours. The satellite appears neutral (grey) in visible light (colour indices B−V=0.80, R−V=0.39),^[9] similar to Setebos but different from Sycorax (which is light red).

See also

• Uranus's natural satellites
• Irregular satellites