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nl:Speculatieve planeet sl:domnevni planet '''Hypothetical planets''' are planets that have been suggested as possibly existing (or have been believed to exist), but have never been proven to actually exist. This includes ones that have later been proven not to exist. Examples of such hypothetical planets in astronomy or in ancient mythologies include: ===Sol System=== ====Planets which would have a direct influence on Earth==== * Counter-Earth: An Earth-like planet on Earth's orbit but on the other side of the Sun (hypothesized by the Pythagoreans; used by John Norman as the setting for his Gor novels) * Theia, a hypothetical planet which was destroyed in a collision with Earth according to the giant impact theory * Nibiru/Marduk and Tiamet, two planets from Sumerian mythology which supposedly collided to form Earth (a theory which most scientists find dubious) ====Planets with independent influence==== * Planet X (a tenth planet beyond Pluto) * Vulcan, inside the orbit of Mercury (like Planet X, it was proposed to explain orbital peculiarities) ====Other solar planets==== * The Ninth Planet, as originally proposed is not our Pluto, and was found completely by coincidences that ''Pluto'' was where the proposed '''Planet IX''' was supposedly in the sky. * Phaeton, expected to have an orbit between Mars and Jupiter ===Extra Solar Hypotheticals=== * PSR 1829-10's planet, proposed by Andrew G. Lyne of University of Manchester on July 24 1991, was retracted in 1992. A combination of an inaccurate position for the pulsar and a timing model approximating the Earth's orbit about the Sun with a circle yielded processed data resembling that which would have been expected from a pulsar planet with an orbital period of half a year. * PSR 1257+12 D, the proposed fourth planet in the first extra solar planetary system, was retracted due to further detection refinements. (It has subsequently been replaced by a proposal for a comet) *A microlensing event in 1996 of the gravitationally lensed quasar Q0957+561, observed by R. E. Schild in the A lobe of the double imaged quasar, has lead to a controversial, and unconfirmable speculation that a 3 Earth mass planet is possibly in the unknown lensing galaxy, between Earth and the quasar. ==Other Resources== ===See also=== *Giant impact theory *Tom Van Flandern *Planets in science fiction *Hypothetical Sol System bodies *Hypothetical celestial bodies - hypothetical extrasolar celestial bodies *Extrasolar planet *Category:Fictional planets ===External links=== * http://www.seds.org/nineplanets/nineplanets/hypo.html#planetx * http://www.todayinsci.com/7/7_24.htm