87 Sylvia
| Discovery | |
|---|---|
| Discovered by | Norman Robert Pogson |
| Discovery date | 16 May 1866 |
| Designations | |
| (87) Sylvia | |
| Pronunciation | /ˈsɪlviə/ SIL-vee-ə |
Named after | Rhea Silvia |
| A909 GA | |
| main belt · (outside core) Sylvia · Cybele | |
| Adjectives | Sylvian (/ˈsɪlviən/ SIL-vee-ən) |
| Orbital characteristics | |
| Epoch 1 July 2021 (JD 2459396.5, heliocentric) | |
| Aphelion | 3.81 AU (560 Gm) |
| Perihelion | 3.15 AU (480 Gm) |
| 3.48 AU (520 Gm) | |
| Eccentricity | 0.094 |
| 6.5 a (2372 d) | |
Average orbital speed | 15.94 km/s |
| 213° | |
| 0° 9m 6.48s / day | |
| Inclination | 10.9° |
| 73° | |
| 263° | |
| Known satellites | 2 |
| Physical characteristics | |
| Dimensions | (363 × 249 × 191) ±5 km (MPCD) or (374 × 248 × 194) ±5 km (ADAM) |
| 271±5 km (MPCD) or 274±5 km (ADAM) | |
| Volume | (10.5±0.2)×107 km3 (MPCD) or (10.8±0.2)×107 km3 (ADAM) |
| Mass | (14.76±0.06)×1018 kg (14.6±0.1)×1018 kg |
Mean density | 1.378±0.045 g/cm3 |
| 0.2160 d (5.183641±0.000039 h) | |
North pole right ascension | 14.3°±5° |
North pole declination | +83.5°±5° |
Pole ecliptic latitude | +64.2°±5° |
Pole ecliptic longitude | 75.3°±5° |
| 0.0435 | |
| X | |
| 6.94 | |
87 Sylvia is one of the largest asteroids (approximately tied for 7th place, to within measurement uncertainties). It is the parent body of the Sylvia family and member of Cybele group located beyond the main asteroid belt (see minor-planet groups). Sylvia was the first asteroid known to possess more than one moon.