5 Astraea
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| Discovery A (http://cfa-www.harvard.edu/iau/lists/NumberedMPs.html) | |
|---|---|
| Discoverer | Karl Ludwig Hencke |
| Discovery date | December 8, 1845 |
| Alternate designations | 1969 SE B (http://cfa-www.harvard.edu/iau/MPDes.html) |
| Category | Main belt |
| Orbital elements C (http://asteroid.lowell.edu/) Epoch July 14, 2004 (JD 2453200.5) | |
| Eccentricity (e) | 0.1923 |
| Semi-major axis (a) | 384.877 Gm (2.574 AU) |
| Perihelion (q) | 310.509 Gm (2.076 AU) |
| Aphelion (Q) | 459.245 Gm (3.070 AU) |
| Orbital period (P) | 1507.279 d (4.13 a) |
| Mean orbital speed | 18.57 km/s |
| Inclination (i) | 5.36772° |
| Longitude of the ascending node (Ω) | 141.690° |
| Argument of perihelion (ω) | 357.536° |
| Mean anomaly (M) | 75.005° |
| Physical characteristics | |
| Dimensions | 119.1 km |
| Mass | ~1.8×1018 kg |
| Density | 2 ? g/cm³ |
| Surface gravity | ~0.033 m/s² |
| Escape velocity | ~0.063 km/s |
| Rotation period | 0.700 00 d1 (http://www.psi.edu/pds/archive/lc.html) |
| Spectral class | S-type asteroid |
| Absolute magnitude | 6.85 |
| Albedo | 0.227 2 (http://dorothy.as.arizona.edu/DSN/IRAS/index_iras.html) |
| Mean surface temperature | ~167 K |
5 Astraea (as-tree'-a; written Astræa in the early scientific litterature) is a large Main belt asteroid. Its surface is highly reflective (bright) and the composition is probably a mixture of nickel-iron with magnesium- and iron-silicates.
Astraea was the fifth asteroid discovered, on December 8, 1845 by K. L. Hencke. It was his first of two asteroid discoveries. The second was 6 Hebe. An amateur astronomer and post office employee, Hencke was looking for 4 Vesta when he stumbled on Astraea. The King of Prussia awarded him with an annual pension of 300 $ (1968 dollars) for the discovery.
It is notable mainly because for 38 years (since the discovery of Vesta in 1807) it had been thought that there were only four asteroids. After the discovery of Astraea, thousands of other asteroids would follow.
There has been only one observed stellar occultation by Astraea (February 2, 1991).
External links
- AN 23 (1846) 393 (http://adsabs.harvard.edu//full/seri/AN.../0023//0000211.000.html) (in German)
- MNRAS 7 (1846) 27 (http://adsabs.harvard.edu//full/seri/MNRAS/0007//0000027.000.html)
| The minor planets |
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| (For other objects and regions, see: Binary asteroids, Asteroid moons and the Solar system) |
| (For a complete listing, see: List of asteroids. For pronunciation, see: Pronunciation of asteroid names.) |
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