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Sophrosyne (minor planet designation: 134 Sophrosyne) is a large main-belt asteroid that was discovered by German astronomer Robert Luther on September 27, 1873, and was named after the concept of sophrosyne, Plato's term for 'moderation'. Classified as a C-type asteroid, it has an exceedingly dark surface and most probably a primitive carbonaceous composition.

134 Sophrosyne
Discovered byKarl Theodor Robert Luther
Discovery date27 September 1873
MPC designation(134) Sophrosyne
Named after
Main belt
Orbital characteristics[1]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc138.60 yr (50625 d)
Aphelion2.86280 AU (428.269 Gm)
Perihelion2.26311 AU (338.556 Gm)
2.56295 AU (383.412 Gm)
4.10 yr (1498.7 d)
18.54 km/s
0° 14m 24.76s / day
Earth MOID1.31034 AU (196.024 Gm)
Jupiter MOID2.42537 AU (362.830 Gm)
Physical characteristics
112.188 km[2]
Mass2.0×1018 kg
Equatorial surface gravity
0.0345 m/s²
Equatorial escape velocity
0.0652 km/s
17.190 h (0.7163 d)[3]
0.0436 ± 0.0122[2]
Temperature~174 K
C (Tholen)[2]
8.76,[1] 8.770[2]

An occultation of a star by 134 Sophrosyne was observed November 24, 1980, in the United States. Timing information from this event allowed a diameter estimate of 110 km to be derived.[4] Photometric observations of the asteroid in 2015 produced a lightcurve indicating a rotation period of 17.190±0.001 h with a variation amplitude of 0.28±0.01 in magnitude. This provided a good match to the only previous determination in 1989.[3]


  1. ^ a b c d Yeomans, Donald K., "134 Sophrosyne", JPL Small-Body Database Browser, NASA Jet Propulsion Laboratory, retrieved 12 May 2016.
  2. ^ a b c d Pravec, P.; et al. (May 2012), "Absolute Magnitudes of Asteroids and a Revision of Asteroid Albedo Estimates from WISE Thermal Observations", Asteroids, Comets, Meteors 2012, Proceedings of the conference held May 16–20, 2012 in Niigata, Japan (1667), Bibcode:2012LPICo1667.6089P.
  3. ^ a b Pilcher, Frederick (October 2015), "Rotation Period Determination for 134 Sophrosyne, 521 Brixia and 873 Mechthild", The Minor Planet Bulletin, 42 (4): 280−281, Bibcode:2015MPBu...42..280P.
  4. ^ Taylor, G. E., "Progress in accurate determinations of diameters of minor planets", Asteroids, comets, meteors; Proceedings of the Meeting, Uppsala, Sweden, June 20–22, 1983, pp. 107–109, Bibcode:1983acm..proc..107T.

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