Solar System trans-Neptunian objects

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

Pluto A trans-Neptunian object that is the second largest dwarf planet so far known and the tenth largest body in the solar system. It was discovered in 1930 by Clyde... 

Asteroids, comets and smaller particles are also grouped into SSSBs, small solar system bodies. All categories of objects described above appear at specific locations in the solar system. The inner solar system contains the terrestrial planets and the Main Belt of asteroids. In the middle region there are the giant planets with their satellites and the centaurs. The outer solar system comprises the Trans-Neptunian objects including the Kuiper Belt, the Oort cloud, and the vast region in between. 

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). 

Low-albedo objects are diverse in opposition behavior. Actually, asteroids of the primitive P and F types, located mainly in the outer asteroid belt, show linear phase curves down to phase angles of 2° [49,50], The first tentative phase curves for other dark and distant Solar system objects, like Centaurs and trans-Neptunian (Kuiper Belt) objects, also show linear phase dependence at small phase angles. However their phase curve slope is at least twice as large as that of low-albedo asteroids [51], For both types of dark objects there is an indication of a veiy narrow opposition surge at sub-degree phase angles. 

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