132 Aethra

132 Aethra is a metallic asteroid and Mars-crosser on an eccentric orbit from the asteroid belt. It measures approximately 40 kilometers in diameter.

132 Aethra

Lightcurve-based 3D-model of Aethra
Discovery
Discovered by	James C. Watson
Discovery date	13 June 1873
Designations
MPC designation	(132) Aethra
Pronunciation	/ˈiːθrə/[1]
Named after	Aethra
Alternative designations	A873 LA; 1922 XB; 1949 MD; 1953 LF
Minor planet category	Mars crosser
Orbital characteristics[2]
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°
Argument of perihelion	255.216°
Physical characteristics
Mean diameter	42.87±1.6 km[2] 44.47±0.74 km[3]
Mass	(1.59 ± 0.89/0.42)×1017 kg[3]
Mean density	3.447 ± 1.935/0.923 g/cm3[3]
Synodic rotation period	5.1684 h (0.21535 d)[2]
Geometric albedo	0.1990±0.015[2]
Spectral type	M
Absolute magnitude (H)	8.96[2]

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.^[4][5]

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.