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Star field showing asteroid Thetis in the center
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Discovery
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| Discovered by | R. Luther |
| Discovery date | April 17, 1852 |
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Designations
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| Named after | Thetis |
| Alternate name(s) | A913 CA; A916 YF; 1954 SO1 |
| Minor planet category |
Main belt |
| Adjective | Thetidian |
| Epoch October 22, 2004 (JD 2453300.5) | |
| Aphelion | 419.069 Gm (2.801 AU) |
| Perihelion | 319.991 Gm (2.139 AU) |
| Semi-major axis | 369.530 Gm (2.470 AU) |
| Eccentricity | 0.134 |
| Orbital period | 1418.027 d (3.88 a) |
| Average orbital speed | 18.87 km/s |
| Mean anomaly | 38.435° |
| Inclination | 5.587° |
| Longitude of ascending node | 125.622° |
| Argument of perihelion | 135.906° |
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Physical characteristics
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| Dimensions | 90 km[1] |
| Mass | 1.2×1018 kg[2][3] |
| Mean density | 3.21 ± 0.92 g/cm³[2] |
| Equatorial surface gravity | 0.0252 m/s² |
| Escape velocity | 0.0476 km/s |
| Rotation period | 0.5113 d (12.27 h)[1][4] |
| Albedo | 0.1715 [1][5] |
| Temperature | ~173 K |
| Spectral type | S[1] |
| Apparent magnitude | 9.89 to 13.51[6] |
| Absolute magnitude (H) | 7.76[1] |
17 Thetis ( /ˈθiːtɨs/; Greek: Θέτις) is a large main-belt asteroid. It is an S-type asteroid, therefore giving it a relatively bright silicate surface.
It was discovered by R. Luther on April 17, 1852. It was his first asteroid discovery. Its name comes from Thetis, the mother of Achilles in Greek mythology.[7]
One Thetidian stellar occultation was observed from Oregon in 1999. However, the event was not timed.
The mass of Thetis has been calculated from perturbations by 4 Vesta and 11 Parthenope. In 2007, Baer and Chesley calculated Thetis to have a mass of 1.2×1018 kg[2][3] with a density of 3.21 g/cm³.[2]
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