English

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Etymology

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From cis- +‎ Neptunian; compare trans-Neptunian.

Adjective

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cis-Neptunian (not comparable)

  1. (astronomy) Relating to an astronomical body found within the orbit of Neptune.
    • 2018, Michael Perryman, The Exoplanet Handbook, Cambridge University Press, →ISBN, page 684:
      Within the orbit of Neptune, cis-Neptunian bodies include the terrestrial and large gaseous planets, along with a variety of minor bodies: planetary moons, asteroids, and comets.

Usage notes

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  • The definition is somewhat vague: an object whose orbit is only partly inside that of Neptune might be neither cis-Neptunian nor trans-Neptunian – or perhaps both.
  • The term is usually only applied to small Solar System bodies that directly orbit the Sun. It also may be stipulated that the orbit be beyond that of Jupiter.
  • Neptunian trojans, which share Neptune's orbit, may or may not be included.

Further reading

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