103 Hera

Hera (minor planet designation: 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.

103 Hera
Discovered byJames Craig Watson[1]
Discovery date7 September 1868[1]
(103) Hera
Named after
1927 CV, 1950 CM
Main belt
Orbital characteristics[3]
Epoch 31 July 2016 (JD 2457600.5)[1]
Uncertainty parameter 0
Observation arc144.99 yr (52958 d)
Aphelion2.92042 AU (436.889 Gm)[1]
Perihelion2.48175 AU (371.265 Gm)[1]
2.70109 AU (404.077 Gm)[1]
4.44 yr (1621.5 d)[1]
18.09 km/s
0° 13m 19.279s / day
Earth MOID1.46898 AU (219.756 Gm)
Jupiter MOID2.32392 AU (347.653 Gm)
Physical characteristics
Dimensions91.20±5.6 km
Mass7.9×1017 kg
Equatorial surface gravity
0.0255 m/s²
Equatorial escape velocity
0.0482 km/s
23.740 h (0.9892 d)[3]
0.9892 d[4]
Temperature~170 K

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]


  1. ^ a b c d e f g h JPL Small-Body Database Browser, JPL, retrieved 30 October 2020
  2. ^ "Hera". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
  3. ^ a b Yeomans, Donald K., "103 Hera", JPL Small-Body Database Browser, NASA Jet Propulsion Laboratory, retrieved 12 May 2016.
  4. ^ a b Pilcher, Frederick (January 2011), "Rotation Period Determination for 103 Hera", The Minor Planet Bulletin, 38 (1), p. 32, Bibcode:2011MPBu...38...32P.
  5. ^ a b DeMeo, Francesca E.; et al. (2011), "An extension of the Bus asteroid taxonomy into the near-infrared" (PDF), Icarus, 202 (1): 160–180, Bibcode:2009Icar..202..160D, doi:10.1016/j.icarus.2009.02.005, archived from the original (PDF) on 17 March 2014, retrieved 22 March 2013. See appendix A.
  6. ^ "Numbered Minor Planets 1–5000", Discovery Circumstances, IAU Minor Planet center, retrieved 7 April 2013.
  7. ^ Ryan, Erin Lee; et al. (April 2012), "The Kilometer-Sized Main Belt Asteroid Population as Revealed by Spitzer", arXiv:1204.1116 [astro-ph.EP].

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