93 Minerva

93 Minerva is a large triple main-belt asteroid. It is a C-type asteroid, meaning that it has a dark surface and possibly a primitive carbonaceous composition. It was discovered by J. C. Watson on 24 August 1867, and named after Minerva, the Roman equivalent of Athena, goddess of wisdom. An occultation of a star by Minerva was observed in France, Spain and the United States on 22 November 1982. An occultation diameter of ~170 km was measured from the observations. Since then two more occultations have been observed, which give an estimated mean diameter of ~150 km.^[5][6]

93 Minerva

A three-dimensional model of 93 Minerva based on its light curve.
Discovery
Discovered by	James Craig Watson
Discovery site	Ann Arbor, Michigan
Discovery date	24 August 1867
Designations
MPC designation	(93) Minerva
Pronunciation	/mɪˈnɜːrvə/[1]
Named after	Minerva
Alternative designations	1949 QN2, A902 DA
Minor planet category	Main belt
Adjectives	Minervian, Minervean /mɪˈnɜːrviən/
Orbital characteristics[2]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc	146.14 yr (53379 d)
Aphelion	3.1429 AU (470.17 Gm)
Perihelion	2.3711 AU (354.71 Gm)
Semi-major axis	2.7570 AU (412.44 Gm)
Eccentricity	0.13998
Orbital period (sidereal)	4.58 yr (1672.0 d)
Average orbital speed	~17.86 km/s
Mean anomaly	262.022°
Mean motion	0° 12m 55.116s / day
Inclination	8.56143°
Longitude of ascending node	4.06265°
Argument of perihelion	274.543°
Physical characteristics
Mean diameter	154.155±1.298 km (IRAS)[2] 156 km[3]
Mass	3.8×1018 kg (calculated)[a]
Mean density	1.9 g/cm3[3]
Equatorial surface gravity	4.139 cm/s2 (0.004221 g)[4]
Equatorial escape velocity	81 m/s[4]
Synodic rotation period	5.982 h (0.2493 d)[2]
Geometric albedo	0.056±0.008[2]
Spectral type	C[2] G?[3]
Absolute magnitude (H)	7.91[2]

Satellites

On 16 August 2009, at 13:36 UT, the Keck Observatory's adaptive optics system revealed that the asteroid 93 Minerva possesses 2 small moons.^[7] They are 4 and 3 km in diameter and the projected separations from Minerva correspond to 630 km (8.8 x Rprimary) and 380 km (5.2 x Rprimary) respectively.^[7] They have been named Aegis^[8] (/ˈiːdʒɪs/)^[9] and Gorgoneion^[8] (/ˌɡɔːrɡəˈnaɪən/).^[10]

Notes

1. Using a spherical radius of 78 km; volume of a sphere * density of 1.9 g/cm³ yields a mass (m=d*v) of 3.78E+18 kg