140 Siwa
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Discovery
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| Discovered by | Johann Palisa |
| Discovery date | October 13, 1874 |
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Designations
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| Minor planet category |
Main belt |
| Epoch December 31, 2006 (JD 2454100.5) | |
| Aphelion | 497.275 Gm (3.324 AU) |
| Perihelion | 320.360 Gm (2.141 AU) |
| Semi-major axis | 408.817 Gm (2.733 AU) |
| Eccentricity | 0.216 |
| Orbital period | 1650.076 d (4.52 a) |
| Average orbital speed | 17.80 km/s |
| Mean anomaly | 156.165° |
| Inclination | 3.187° |
| Longitude of ascending node | 107.292° |
| Argument of perihelion | 197.230° |
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Physical characteristics
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| Dimensions | 109.8 km |
| Mass | 1.4×1018 kg |
| Mean density | ? g/cm³ |
| Equatorial surface gravity | 0.0307 m/s² |
| Escape velocity | 0.0580 km/s |
| Rotation period | ? d |
| Albedo | ? |
| Temperature | ~168 K |
| Spectral type | P |
| Absolute magnitude | 8.34 |
140 Siwa (pronounced /ˈʃiːwə/?) is a large and dark main belt asteroid. It has a composition of a P (or possibly C-type) asteroid. It was discovered by J. Palisa on October 13, 1874 and named after Šiwa, the Slavic goddess of fertility. Siwa has a very flat lightcurve, indicating a spherical body.
The Rosetta comet probe was to visit Siwa on its way to comet 46P/Wirtanen in July, 2008. However, the mission was rerouted to comet 67P/Churyumov-Gerasimenko and the flyby had to be abandoned.
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