5 Astraea
Astraea (/æˈstriːə/) (minor planet designation: 5 Astraea) is an asteroid in the asteroid belt. Its surface is highly reflective and its composition is probably a mixture of nickel–iron with silicates of magnesium and iron. It is an S-type asteroid in the Tholen classification system.
Lightcurve-based 3D-model of Astraea | |
| Discovery | |
|---|---|
| Discovered by | K. L. Hencke |
| Discovery site | Driesen Obs. |
| Discovery date | 8 December 1845 |
| Designations | |
MPC designation | (5) Astraea |
| Pronunciation | /æˈstriːə/ |
Named after | Astraea (Greek goddess) |
Alternative designations | 1969 SE |
Minor planet category | main-belt · (middle) Astraea |
| Adjectives | Astraean |
| Symbol | (historical astronomical), (modern astrological) |
| Orbital characteristics | |
| Epoch 23 March 2018 (JD 2458200.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 171.93 yr (62,799 d) |
| Aphelion | 3.0659 AU |
| Perihelion | 2.0810 AU |
Semi-major axis | 2.5735 AU |
| Eccentricity | 0.1914 |
Orbital period (sidereal) | 4.13 yr (1,508 d) |
Mean anomaly | 186.83° |
Mean motion | 0° 14m 19.32s / day |
| Inclination | 5.3677° |
Longitude of ascending node | 141.58° |
| 358.75° | |
| Proper orbital elements | |
Proper semi-major axis | 2.5761849 AU |
Proper eccentricity | 0.1980486 |
Proper inclination | 4.5118628° |
Proper mean motion | 87.046396 deg / yr |
Proper orbital period | 4.13573 yr (1510.574 d) |
Precession of perihelion | 52.210903 arcsec / yr |
Precession of the ascending node | −57.357951 arcsec / yr |
| Physical characteristics | |
| Dimensions | 169 km × 125 km × 83 km |
Mean diameter | 125 km |
Surface area | 48 900 km2 |
| Volume | 920 000 km3 |
| Mass | (2.716 ± 0.326/0.45)×1018 kg |
Mean density | 3.501 ± 0.420/0.581 g/cm3 |
Synodic rotation period | 0.700 04 d (16.801 h) |
Equatorial rotation velocity | 6.49 m/s |
North pole right ascension | 115°/310° ± 5° |
North pole declination | 55° ± 5° |
| 0.227 | |
| S | |
| 8.74 to 12.89 | |
| 6.85 | |
| 0.15" to 0.041" | |
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