(118) Peitho

118 Peitho
Discovered byKarl Theodor Robert Luther
Discovery date15 March 1872
(118) Peitho
Named after
Πειθώ Peithō
Main belt
AdjectivesPeithoian /pˈθ.iən/
Orbital characteristics[2]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc144.05 yr (52615 d)
Aphelion2.8353 AU (424.15 Gm)
Perihelion2.03988 AU (305.162 Gm)
2.43757 AU (364.655 Gm)
3.81 yr (1390.1 d)
18.95 km/s
0° 15m 32.328s / day
Earth MOID1.05849 AU (158.348 Gm)
Jupiter MOID2.4367 AU (364.53 Gm)
Physical characteristics
Dimensions41.73±1.5 km
Mass7.6×1016 kg
Equatorial surface gravity
0.0117 m/s2
Equatorial escape velocity
0.0220 km/s
7.8055 h (0.32523 d)[2]
7.823 h[3]
Temperature~178 K

Peitho (minor planet designation: 118 Peitho) is a main-belt asteroid. It is probably an S-type asteroid, suggesting a siliceous mineralogy. It was discovered by R. Luther on March 15, 1872, and named after one of the two Peithos in Greek mythology. There have been two observed Peithoan occultations of a dim star: one was in 2000 and the other in 2003.[4][5]

This body is orbiting the Sun with a period of 3.81 years and an eccentricity (ovalness) of 0.16. The orbital plane is inclined by 7.7° to the plane of the ecliptic. The cross-section diameter is ~42 km. In 2009, Photometric observations of this asteroid were made at the Palmer Divide Observatory in Colorado Springs, Colorado. The resulting asymmetrical light curve shows a synodic rotation period of 7.823 ± 0.002 hours with a brightness variation of 0.15 ± 0.02 in magnitude. This was reasonably consistent with independent studies performed in 1980 (7.78 hours) and 2009 (7.8033 hours).[3] The lightcurve inversion process has been used to construct a model of this object,[6] suggesting a blocky shape with flattened poles.


  1. ^ 'Pitho' in Noah Webster (1884) A Practical Dictionary of the English Language
  2. ^ a b Yeomans, Donald K., "118 Peitho", JPL Small-Body Database Browser, NASA Jet Propulsion Laboratory, retrieved 12 May 2016.
  3. ^ a b Warner, Brian D. (October 2009), "Asteroid Lightcurve Analysis at the Palmer Divide Observatory: 2009 March-June", The Minor Planet Bulletin, vol. 36, no. 4, pp. 172–176, arXiv:1203.4336, Bibcode:2009MPBu...36..172W, doi:10.1016/j.pss.2012.03.009.
  4. ^ von Boinik, I. F. B. "Planet (118) Peitho". Astronomische Nachrichten. 145: 31. Bibcode:1897AN....145...31V. doi:10.1002/asna.18981450107.
  5. ^ "NASA Planetary Data System". Archived from the original on 1 August 2009. Retrieved 21 December 2009.
  6. ^ Franco, Lorenzo; et al. (July 2020), "Spin-Shape Model for 118 Peitho", Bulletin of the Minor Planets Section of the Association of Lunar and Planetary Observers, 47 (3): 169–171, Bibcode:2020MPBu...47..169F

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