103 Hera

103 Hera is a moderately large main-belt asteroid with an orbital period of 4.44 years. It was discovered by Canadian-American astronomer James Craig Watson on September 7, 1868,^[6] and named after Hera, queen and fifth in power of the Olympian gods in Greek mythology. This is a stony S-type asteroid^[5] with a silicate surface composition.

DiscoveredbyJames Craig Watson^[1]

Discoverydate7 September 1868^[1]

MPCdesignation

(103) Hera

Pronunciation/ˈhɪərə/^[2]

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103 Hera

3D convex shape model of 103 Hera
Discovery
Discovered by	James Craig Watson[1]
Discovery date	7 September 1868[1]
Designations
MPC designation	(103) Hera
Pronunciation	/ˈhɪərə/[2]
Named after	Hera
Alternative designations	A868 RA, 1927 CV 1950 CM
Minor planet category	Main belt
Orbital characteristics[3]
Epoch 31 July 2016 (JD 2457600.5)[1]
Uncertainty parameter 0
Observation arc	144.99 yr (52958 d)
Aphelion	2.92042 AU (436.889 Gm)[1]
Perihelion	2.48175 AU (371.265 Gm)[1]
Semi-major axis	2.70109 AU (404.077 Gm)[1]
Eccentricity	0.0812034[1]
Orbital period (sidereal)	4.44 yr (1621.5 d)[1]
Average orbital speed	18.09 km/s
Mean anomaly	133.341°
Mean motion	0° 13m 19.279s / day
Inclination	5.41957°
Longitude of ascending node	136.186°
Argument of perihelion	188.361°
Earth MOID	1.46898 AU (219.756 Gm)
Jupiter MOID	2.32392 AU (347.653 Gm)
TJupiter	3.356
Physical characteristics
Dimensions	91.20±5.6 km
Mass	7.9×1017 kg
Equatorial surface gravity	0.0255 m/s²
Equatorial escape velocity	0.0482 km/s
Synodic rotation period	23.740 h (0.9892 d)[3] 0.9892 d[4]
Geometric albedo	0.1833±0.025
Temperature	~170 K
Spectral type	S[5]
Absolute magnitude (H)	7.66

Close

Photometric observations made in 2010 at the Organ Mesa Observatory at Las Cruces, New Mexico, and the Hunters Hill Observatory at Ngunnawal, Australian Capital Territory, give a synodic rotation period of 23.740±0.001 h. The bimodal light curve shows a maximum brightness variation of 0.45 ± 0.03 in magnitude.^[4]

Measurements made with the IRAS observatory give a diameter of 91.58±4.14 km and a geometric albedo of 0.19±0.02. By comparison, the MIPS photometer on the Spitzer Space Telescope gives a diameter of 88.30±8.51 km and a geometric albedo of 0.20±0.04. When the asteroid was observed occulting a star, the chords showed a diameter of 89.1±1.1 km.^[7]