54 Alexandra
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Discovery
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| Discovered by | Hermann Mayer Salomon Goldschmidt |
| Discovery date | September 10, 1858 |
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Designations
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| Alternative names | |
| Minor planet category |
Main belt |
| Epoch December 31, 2006 (JD 2454100.5) | |
| Aphelion | 485.483 Gm (3.245 AU) |
| Perihelion | 326.043 Gm (2.179 AU) |
| Semi-major axis | 405.763 Gm (2.712 AU) |
| Eccentricity | 0.196 |
| Orbital period | 1631.620 d (4.47 a) |
| Average orbital speed | 17.91 km/s |
| Mean anomaly | 103.809° |
| Inclination | 11.804° |
| Longitude of ascending node | 313.446° |
| Argument of perihelion | 345.594° |
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Physical characteristics
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| Dimensions | 165.8 km |
| Mass | ~5×1018 kg |
| Mean density | ? g/cm³ |
| Equatorial surface gravity | 0.0463 m/s² |
| Escape velocity | 0.0877 km/s |
| Rotation period | ? d |
| Albedo | 0.056 [1] |
| Temperature | ~169 K |
| Spectral type | C |
| Absolute magnitude | 7.66 |
54 Alexandra is a very large and dark main belt asteroid. It was discovered by H. Goldschmidt on September 10, 1858 and named after the German explorer Alexander von Humboldt. On May 17, 2005 this asteroid occulted a faint star (magnitude 8.5) and the event was observed and timed in a number of locations within the U.S. and Mexico. As a result a silhouette profile was produced, yielding a roughly oval cross-section with dimensions of 160 × 135 km (± 1 km).[2]
[edit] Notes and references
- ^ Asteroid Data Sets
- ^ D.W. Dunham, "Upcoming Asteroid Occultations", Sky & Telescope, June, 2006, p. 63.
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