17 Thetis
Thetis, minor planet designation 17 Thetis, is a stony asteroid from the inner regions of the asteroid belt, approximately 90 kilometers in diameter. It was discovered on 17 April 1852, by German astronomer Robert Luther at Bilk Observatory in Düsseldorf, Germany who deferred to Friedrich Wilhelm August Argelander the naming his first asteroid discovery after Thetis from Greek mythology. Its historical symbol was a dolphin and a star; it is in the pipeline for Unicode 17.0 as U+1CECA ().
Star field showing asteroid Thetis in the center | |
| Discovery | |
|---|---|
| Discovered by | R. Luther |
| Discovery site | Düsseldorf-Bilk Obs. |
| Discovery date | 17 April 1852 |
| Designations | |
MPC designation | (17) Thetis |
| Pronunciation | /ˈθiːtɪs/ |
Named after | Thetis (Greek mythology) |
Alternative designations | 1954 SO1 · A913 CA A916 YF |
Minor planet category | main-belt · (inner) |
| Adjectives | Thetidian /θɛˈtɪdiən/ |
| Symbol | (historical) |
| Orbital characteristics | |
| Epoch 16 February 2017 (JD 2457800.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 164.55 yr (60,102 days) |
| Aphelion | 2.7987 AU |
| Perihelion | 2.1436 AU |
Semi-major axis | 2.4712 AU |
| Eccentricity | 0.1325 |
Orbital period (sidereal) | 3.88 yr (1,419 days) |
Average orbital speed | 18.87 km/s |
Mean anomaly | 100.44° |
Mean motion | 0° 15m 13.32s / day |
| Inclination | 5.5902° |
Longitude of ascending node | 125.56° |
| 136.10° | |
| Physical characteristics | |
| Dimensions | 84.899±2.027 90±3.7km (IRAS) 93.335±2.627 |
| Mass | 1.2×1018 kg |
Mean density | 3.21±0.92 g/cm3 |
Synodic rotation period | 12.27048±0.00001 |
| 0.193±0.028 | |
| B–V = 0.829 U–B = 0.438 S (Tholen) Sl (SMASS) · S | |
| 7.76 · 7.85 | |
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