Solar System/Trans-Neptunian objects

Trans-Neptunian objects, as their name suggests, are objects in the solar system that are farther from the Sun than the outermost planet, Neptune. The most famous of these, and the first discovered, is Pluto. Any trans-Neptunian dwarf planet is called a plutoid. Pluto is in the Kuiper belt of objects that begins immediately beyond the orbit of Neptune. Overlapping and beyond the Kuiper belt is the scattered disc, and far beyond the Kuiper belt is the Oort cloud. The Kuiper Belt is the source of short-period comets, and the Oort Cloud is the source of long-period comets. There are seven Trans-Neptunian objects which are probably dwarf planets, and one that is known for sure to be a dwarf planet. Orcus, a probable dwarf planet in the Kuiper belt Pluto, a known dwarf planet in the Kuiper belt Makemake, a probable dwarf planet in the Kuiper Belt Quaoar, a probable dwarf planet in the Kuiper Belt Haumea, a probable dwarf planet in the Kuiper Belt Gonggong, a probable dwarf planet in the scattered disc Eris, a probable dwarf planet in the scattered disc Sedna, a probable dwarf planet in the scattered disc or the Oort Cloud In addition to those, there are several dwarf planet candidates. These are Máni, Aya, Achlys, Varda, Ixion, Chiminigagua, Varuna, Uni, Ritona, Rumina, Xewioso, Huya, and Goibniu. There is one object, Arrokoth, which is known not to be a dwarf planet, and was visited by New Horizons in 2019.