 Discovery image of Prospero, taken by the CFHT in July 1999 | |
| Discovery | |
|---|---|
| Discovered by | |
| 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] |
| 1978.29 d | |
| Inclination | 152° [4] (to the ecliptic) [4] |
| Satellite of | Uranus |
| Physical characteristics | |
| 25 km (estimate) [6] <50 km [7] | |
| ~8000 km2 (estimate) | |
| Volume | ~65,000 km3 (estimate) |
| Mass | ~8.5×1016 kg (estimate) |
Mean density | ~1.3 g/cm3 (assumed) |
| ~0.0063 m/s2 (estimate) | |
| ~0.021 km/s (estimate) | |
| 7.145±0.092 h [7] | |
| ? | |
| Albedo | 0.04 (assumed) [6] |
| Temperature | ~65 K (estimate) |
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 .
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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).
