331 Etheridgea

331 Etheridgea is a large main belt asteroid.^[1] It was discovered by Auguste Charlois on 1 April 1892 in Nice. The meaning of the name is unknown.^[2] This asteroid is orbiting the Sun at a distance of 3.02 AU with a period of 5.26 years and an eccentricity (ovalness) of 0.10. The orbital plane is tilted at an angle of 6.05° to the plane of the ecliptic.^[1]

331 Etheridgea

Orbital diagram
Discovery
Discovered by	Auguste Charlois
Discovery date	1 April 1892
Designations
MPC designation	(331) Etheridgea
Pronunciation	/ˌɛθəˈrɪdʒiə/
Named after	Possibly Robert Etheridge
Minor planet category	Main belt
Orbital characteristics[1]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc	123.95 yr (45,274 d)
Aphelion	3.32623 AU (497.597 Gm)
Perihelion	2.72055 AU (406.988 Gm)
Semi-major axis	3.02339 AU (452.293 Gm)
Eccentricity	0.10016
Orbital period (sidereal)	5.26 yr (1,920.2 d)
Mean anomaly	88.5392°
Mean motion	0° 11m 14.939s / day
Inclination	6.05385°
Longitude of ascending node	22.0346°
Argument of perihelion	333.055°
Physical characteristics
Dimensions	74.92±2.7 km
Synodic rotation period	25.315 h (1.0548 d)
Geometric albedo	0.0447±0.003
Absolute magnitude (H)	9.62

Analysis of the asteroid light curve generated from photometric data collected in 2015 provided a rotation period of 25.315±0.001 h. This result is completely different from the previous rotation period estimates.^[3] It is a low albedo, carbonaceous C-type asteroid and spans a girth of 74.9±2.7 km.^[4]

It may have been named for the geologist and paleontologist Robert Etheridge (1819–1903).^[5][6]