132 Aethra
Aethra (minor planet designation: 132 Aethra) is a metallic asteroid and Mars-crosser on an eccentric orbit from the asteroid belt. It measures approximately 40 kilometers in diameter.
Lightcurve-based 3D-model of Aethra | |
Discovery | |
---|---|
Discovered by | James C. Watson |
Discovery date | 13 June 1873 |
Designations | |
MPC designation | (132) Aethra |
Pronunciation | /ˈiːθrə/ |
Named after | Aethra |
Alternative designations | A873 LA; 1922 XB; 1949 MD; 1953 LF |
Minor planet category | Mars crosser |
Orbital characteristics | |
Epoch 31 July 2016 (JD 2457600.5) | |
Uncertainty parameter 0 | |
Observation arc | 142.50 yr (52049 d) |
Aphelion | 3.6250 AU (542.29 Gm) |
Perihelion | 1.5895 AU (237.79 Gm) |
Semi-major axis | 2.6073 AU (390.05 Gm) |
Eccentricity | 0.39036 |
Orbital period (sidereal) | 4.21 yr (1537.7 d) |
Average orbital speed | 17.72 km/s |
Mean anomaly | 38.271° |
Mean motion | 0° 14m 2.796s / day |
Inclination | 24.997° |
Longitude of ascending node | 258.408° |
255.216° | |
Physical characteristics | |
Mean diameter | 42.87±1.6 km 44.47±0.74 km |
Mass | (1.59 ± 0.89/0.42)×1017 kg |
Mean density | 3.447 ± 1.935/0.923 g/cm3 |
Synodic rotation period | 5.1684 h (0.21535 d) |
0.1990±0.015 | |
M | |
8.96 | |
It was discovered by James Craig Watson in 1873 and is the first such Mars-crosser asteroid to be identified. As a Mars-crosser asteroid, Aethra is the lowest numbered asteroid to not have proper orbital elements due to recurring perturbations by Mars. It has a rather eccentric orbit that sometimes brings it closer to the Sun than the planet Mars.
With an original observation arc of only 22 days, 132 Aethra was a lost asteroid between 1873 and 1922.
The varying light curve of the asteroid implies an elongated or irregular shape for its body.
It is named after Aethra, the mother of Theseus in Greek mythology.