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Semele (/ˈsɛmɪl/ SEM-i-lee; minor planet designation: 86 Semele) 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.

86 Semele
Discovered byFriedrich Tietjen
Discovery dateJanuary 4, 1866
MPC designation(86) Semele
Named after
Main belt
Orbital characteristics[1]
Epoch December 31, 2006 (JD 2454100.5)
Aphelion562.652 Gm (3.761 AU)
Perihelion369.116 Gm (2.467 AU)
465.884 Gm (3.114 AU)
2,007.366 d (5.50 a)
16.69 km/s
Physical characteristics
Dimensions120.6 km
Mass1.8×1018 kg
Equatorial surface gravity
0.0337 m/s²
Equatorial escape velocity
0.0638 km/s
0.047 [2]

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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