87 Sylvia
Sylvia (minor planet designation: 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.
| Discovery | |
|---|---|
| Discovered by | Norman Robert Pogson |
| Discovery date | May 16, 1866 |
| Designations | |
MPC designation | (87) Sylvia |
| Pronunciation | /ˈsɪlviə/ SIL-vee-ə |
Named after | Rhea Silvia |
Alternative designations | A909 GA |
Minor planet category | main belt · (outside core) Sylvia · Cybele |
| Adjectives | Sylvian (/ˈsɪlviən/ SIL-vee-ən) |
| Orbital characteristics | |
| Epoch July 01, 2021 (JD 2459396.5, heliocentric) | |
| Aphelion | 3.81 AU (560 Gm) |
| Perihelion | 3.15 AU (480 Gm) |
Semi-major axis | 3.48 AU (520 Gm) |
| Eccentricity | 0.094 |
Orbital period (sidereal) | 6.5 a (2372 d) |
Average orbital speed | 15.94 km/s |
Mean anomaly | 213° |
Mean motion | 0° 9m 6.48s / day |
| Inclination | 10.9° |
Longitude of ascending node | 73° |
| 263° | |
| Known satellites | 2 |
| Physical characteristics | |
| Dimensions | (363 × 249 × 191) ±5 km (MPCD) or (374 × 248 × 194) ±5 km (ADAM) |
Mean diameter | 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 |
Synodic rotation period | 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 | |
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