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‡ Trans–Neptunian dwarf planets are "plutoids" |
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. This includes the icy minor planets known as centaurs[2] and the Neptune trojans.[3]
Centaurs orbit the Sun between Jupiter and Neptune, often crossing the orbits of the large gas giant planets. 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 2010, all known Neptune trojans except one lie in an elongated region around the L4 Lagrangian point 60° ahead of Neptune.
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