86 Semele

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86 Semele
Discovered by Friedrich Tietjen
Discovery date January 4, 1866
MPC designation (86) Semele
Named after
Main belt
Orbital characteristics[1]
Epoch December 31, 2006 (JD 2454100.5)
Aphelion 562.652 Gm (3.761 AU)
Perihelion 369.116 Gm (2.467 AU)
465.884 Gm (3.114 AU)
Eccentricity 0.208
2,007.366 d (5.50 a)
16.69 km/s
Inclination 4.822°
Physical characteristics
Dimensions 120.6 km
Mass 1.8×1018 kg
Equatorial surface gravity
0.0337 m/s²
Equatorial escape velocity
0.0638 km/s
0.047 [2]

86 Semele (/ˈsɛmɪl/ SEM-i-lee) is a large and very dark main-belt asteroid. It is probably composed of carbonates. Semele was discovered by German astronomer Friedrich Tietjen on January 4, 1866.[3] It was his first and only asteroid discovery. It is named after Semele, the mother of Dionysus in Greek mythology.

The orbit of 86 Semele places it in a 13:6 mean motion resonance with the planet Jupiter. The computed Lyapunov time for this asteroid is only 6,000 years, indicating that it occupies a chaotic orbit that will change randomly over time because of gravitational perturbations of the planets. This Lyapunov time is the second lowest among the first 100 named minor planets.[4]


  1. ^ Yeomans, Donald K., "86 Semele", JPL Small-Body Database Browser, NASA Jet Propulsion Laboratory, retrieved 2013-04-07. 
  2. ^ Asteroid Data Sets Archived 2010-01-17 at WebCite
  3. ^ "Numbered Minor Planets 1–5000", Discovery Circumstances, IAU Minor Planet center, retrieved 2013-04-07. 
  4. ^ Šidlichovský, M. (1999), Svoren, J.; Pittich, E. M.; Rickman, H., eds., "Resonances and chaos in the asteroid belt", Evolution and source regions of asteroids and comets : proceedings of the 173rd colloquium of the International Astronomical Union, held in Tatranska Lomnica, Slovak Republic, August 24–28, 1998, pp. 297–308, Bibcode:1999esra.conf..297S. 

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