Cis-Neptunian object

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A cis-Neptunian object is, literally, any astronomical body found within the orbit of Neptune.[1] However, the term is typically used for those distant minor planets other than trans-Neptunian objects: that is, all sub-planetary bodies orbiting the Sun at or within the distance of Neptune, but outside the orbit of Jupiter.[citation needed] This includes the icy minor planets known as centaurs[2] and the Neptune trojans.[3][a]

Centaurs orbit the Sun between Jupiter and Neptune, often crossing the orbits of the large gas giants. There is an emerging sense[2] that the centaurs may simply be objects similar to scattered disc objects that were knocked inwards from the Kuiper belt rather than outwards, making them cis-Neptunian rather than trans-Neptunian scattered-disc objects.

Neptune trojans, named by analogy to the Trojan asteroids of Jupiter, are a stable reservoir of small bodies sharing Neptune's orbit.[4] As of August 2012, all known Neptune trojans except two lie in an elongated region around the L4 Lagrangian point 60° ahead of Neptune.



  1. ^ Remo, John L. (2007). Classifying Solid Planetary Bodies. New trends in astrodynamics and applications III. AIP Conference Proceedings, Volume 886, pp. 284-302.
  2. ^ a b J Horner, NW Evans, ME Bailey, DJ Asher (2003). "The Populations of Comet-like Bodies in the Solar System" (PDF). Retrieved 2007-06-29. 
  3. ^ a b "List Of Neptune Trojans". Minor Planet Center. Retrieved 2010-10-27. 
  4. ^ Sheppard, Scott S.; Trujillo, Chadwick A. (June 2006). "A Thick Cloud of Neptune Trojans and Their Colors" (PDF). Science 313 (5786): 511–514. Bibcode:2006Sci...313..511S. doi:10.1126/science.1127173. PMID 16778021. Retrieved 2008-02-26.