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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 ...
Four test orbits of a trans-Plutonian planet have been integrated forward for four million years in order to determine the effects of such a body on the stability of the Neptune–Pluto 3:2 resonance. Planets beyond Pluto with masses of 0.1 and 1.0 Earth masses in orbits at 48.3 and 75.5 AU, respectively, do not disturb the 3:2 resonance.
There are eight planets within the Solar System; planets outside of the solar system are also known as exoplanets. Artist's concept of the potentially habitable exoplanet Kepler-186f As of 7 November 2024, there are 5,787 confirmed exoplanets in 4,320 planetary systems , with 969 systems having more than one planet . [ 1 ]
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.
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 ] ).
This video shows an artist's impression of the free-floating planet CFBDSIR J214947.2-040308.9.. A rogue planet, also termed a free-floating planet (FFP) or an isolated planetary-mass object (iPMO), is an interstellar object of planetary mass which is not gravitationally bound to any star or brown dwarf.
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.
In effect, each orbits the other, forming a binary system informally referred to as a double-dwarf-planet. Pluto's four other moons, Nix, Hydra, Kerberos and Styx are far smaller and orbit the Pluto–Charon system. [5] Among the other dwarf planets, Ceres has no known moons.