Neptune trans-Neptunian objects

The restricted three-body problem Two bodies of finite masses, called primaries, revolve around their common center of mass in circular orbits and a third body with negligible mass moves under their gravitational attraction, but does not affect the orbits of the two primaries. In most astronomical applications the second primary has a small mass compared to the first primary, and consequently the motion of the third, massless, body is a perturbed Keplerian orbit. This is a model for the study of an asteroid (Jupiter being the second primary), a trans-Neptunian object (Neptune being the second primary) or an Earth-like planet in an extrasolar planetary system. 

Trans-Neptunian Object (TNO) Any object in the solar system that orbits the sun at a greater average distance than Neptune. 

All planets from Mercury to Neptune and most of their satellites have been observed from Earth-based telescopes and at least once, some repeatedly, from spacecraft. Therefore, sufficient information was available to emphasize the physical principles in the discussions in Chapter 6. Trans-Neptunian objects and asteroids have been explored to a much lesser degree. Their small sizes, for many their large heliocentric distances, and their low surface temperatures prevented detailed exploration. Until recently, only a few samples of an enormous amount of objects have been investigated. Therefore, the treatment of these objects, grouped in this chapter, is primarily a summary of presently known properties. Section 7.1 discusses Pluto and its satellite Charon Section 7.2 is devoted to comets and Section 7.3 to asteroids. 

We just mention that there is a confusion about naming. The term Trans Neptunian Object (TNO) is used for objects at the outer edge of the Solar system (see Fig. 5.1) here, the KBO are only a subset. Also the term Edgeworth-Kuiper belt is used, and the objects are called EKOs. A review on Trans Neptunian Objects was given by Schulz, 2002 [299]. Many objects are found near the 1 2 resonance with Neptune (while Neptune completes two revolutions about the Sun, the KBO completes only one). 

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