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The number of dwarf planets in the Solar System is unknown. Estimates have run as high as 200 in the Kuiper belt [1] and over 10,000 in the region beyond. [2] However, consideration of the surprisingly low densities of many large trans-Neptunian objects, as well as spectroscopic analysis of their surfaces, suggests that the number of dwarf planets may be much lower, perhaps only nine among ...
Planet V, a planet thought by John Chambers and Jack Lissauer to have once existed between Mars and the asteroid belt, based on computer simulations. Various planets beyond Neptune: Planet Nine, a planet proposed to explain apparent alignments in the orbits of a number of distant trans-Neptunian objects. Planet X, a hypothetical planet beyond ...
Since 2008, there have been five dwarf planets recognized by the IAU, although only Pluto has actually been confirmed to be in hydrostatic equilibrium [25] (Ceres is close to equilibrium, though some anomalies remain unexplained). [26] Ceres orbits in the asteroid belt, between Mars and Jupiter. The others all orbit beyond Neptune.
For the giant planets, the "radius" is defined as the distance from the center at which the atmosphere reaches 1 bar of atmospheric pressure. [ 11 ] Because Sedna and 2002 MS 4 have no known moons, directly determining their mass is impossible without sending a probe (estimated to be from 1.7x10 21 to 6.1×10 21 kg for Sedna [ 12 ] ).
Eris (minor-planet designation: 136199 Eris) is the most massive and second-largest known dwarf planet in the Solar System. [22] It is a trans-Neptunian object (TNO) in the scattered disk and has a high-eccentricity orbit. Eris was discovered in January 2005 by a Palomar Observatory–based team led by Mike Brown and verified later that year.
The largest known trans-Neptunian objects are Pluto and Eris, followed by Haumea, Makemake, Gonggong, Quaoar, Sedna, and Orcus, all of them being officially recognized as dwarf planets by the IAU except for Gonggong, Sedna, and Orcus. There are also many possible dwarf planets, such as Salacia, (307261) 2002 MS 4, Varda, Ixion, and Varuna.
The following is a list of numbered minor planets (essentially the same as asteroids) in ascending numerical order. Minor planets are defined as small bodies in the Solar System, including asteroids, distant objects, and dwarf planets, but not including comets. The catalog consists of hundreds of pages, each containing 1,000 minor planets.
Like Charon compared to Pluto, Vanth is quite large compared to Orcus, and is one reason for characterizing Orcus as the 'anti-Pluto'. If Orcus is a dwarf planet, Vanth would be the third-largest known dwarf-planet moon, after Charon and Dysnomia. The ratio of masses of Orcus and Vanth is uncertain, possibly anywhere from 1:33 to 1:12. [42]