94 Aurora

94 Aurora is one of the largest main-belt asteroids. With an albedo of only 0.04, it is darker than soot, and has a primitive composition consisting of carbonaceous material. It was discovered by J. C. Watson on September 6, 1867, in Ann Arbor, and named after Aurora, the Roman goddess of the dawn.

94 Aurora

A three-dimensional model of 94 Aurora based on its light curve.
Discovery
Discovered by	James Craig Watson
Discovery date	6 September 1867
Designations
MPC designation	(94) Aurora
Pronunciation	/əˈrɔːrə, ɒ-/[1]
Named after	Aurōra
Minor planet category	Main belt
Adjectives	Aurorean /ɔːˈrɔːriən/[2]
Orbital characteristics[3]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc	143.72 yr (52494 d)
Aphelion	3.45175 AU (516.374 Gm)
Perihelion	2.86831 AU (429.093 Gm)
Semi-major axis	3.16003 AU (472.734 Gm)
Eccentricity	0.092315
Orbital period (sidereal)	5.62 yr (2051.8 d)
Average orbital speed	16.73 km/s
Mean anomaly	132.718°
Mean motion	0° 10m 31.638s / day
Inclination	7.97343°
Longitude of ascending node	2.59859°
Argument of perihelion	60.8260°
Physical characteristics
Dimensions	225 × 173 km[4]
Mean diameter	204.89±3.6 km (IRAS)[3]
Mass	(6.606 ± 2.584/2.173)×1018 kg[5]
Mean density	1.676 ± 0.655/0.551 g/cm3[5][a]
Equatorial surface gravity	0.042 m/s²
Equatorial escape velocity	0.0928 km/s
Synodic rotation period	7.22 h (0.301 d)[3]
Geometric albedo	0.0395±0.001[3] 0.0395[6]
Temperature	~157 K
Spectral type	C[3]
Absolute magnitude (H)	7.74[3]

This asteroid is orbiting the Sun with a period of 5.62 years and a relatively low eccentricity of 0.092. It is spinning with a rotation period of 7.22 hours. Observations of an occultation using nine chords indicate an oval outline of 225×173 km.^[4] The asteroid's pole of rotation lies just 4–16° away from the plane of the ecliptic.^[7]

Notes

1. Assuming a diameter of 196 ± 4 km.