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:

Solar System

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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 (while most scientists find this theory absurd, it does bear resemblance to the respected giant impact theory)

Planets with independent influence

See also tenth planet

• Planet X (what was first thought to be a ninth and then a tenth planet beyond Pluto. Pluto was found only because it was near Planet X 's proposed location in the sky.) On 7.29.2005 astronomers have found a new planet in the outer reaches of the solar system. The planet, which hasn't been officially named yet, was found by Brown and colleagues using the Samuel Oschin Telescope at Palomar Observatory near San Diego. It is currently about 97 times farther from the sun than Earth, or 97 Astronomical Units (AU). For comparison, Pluto is 40 AU from the sun. This places the new planet more or less in the Kuiper Belt, a dark realm beyond Neptune where thousands of small icy bodies orbit the sun. The planet appears to be typical of Kuiper Belt objects--only much bigger. Its sheer size in relation to the nine known planets means that it can only be classified as a planet itself, Brown says.

The planet's temporary name is 2003 UB313. (see http://science.nasa.gov/headlines/y2005/29jul_planetx.htm)

• Vulcan, inside the orbit of Mercury (like Planet X, it was proposed to explain orbital peculiarities)

• Phaeton, a fictional planet with an orbit between Mars and Jupiter

Extrasolar hypotheticals

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• PSR 1829-10's planet, proposed by Andrew Lyne of University of Manchester on July 24 1991, was retracted in 1992.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.

List of impossible to confirm exoplanets

(list is very incomplete)

star	planet	minimum mass (x Jupiter)	orbital distance (x Earth)	orbital period (days)
Quasar Q0957+561		3 MEarth

List of doubtful exoplanets

(list is very incomplete)

star	planet	minimum mass (x Jupiter)	orbital distance (x Earth)	orbital period (days)
61 Cygni	b
Aldebaran	b	11 MJupiter	1.35	~653 days
Barnard's Star	b
	c
Lalande 21185	b
	c

List of exoplanets disproven

(list is very incomplete)

star	planet	minimum mass (x Jupiter)	orbital distance (x Earth)	orbital period (days)
Geminga	b
HD 83443	c	54 MEarth	0.174	29.83
MACHO-1997-BLG-41		3.5	7
PSR 1257+12	D	100 MEarth	40	~100 years
PSR 1829-10
TMR-1	C

List of proplyds with gaps and no known planets

when planets are confirmed, please move to the list of confirmed planets (list is very incomplete)

star	gap distance (in AU)	Notes
Beta Pictoris	0 - 50	disc is warped

See also

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• Extrasolar planet
• Category:Fictional planets
• Giant impact theory
• Globus Cassus
• Hypothetical Solar System bodies
• Planets in science fiction
• Tom Van Flandern
• PlanetQuest

External links

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• http://www.seds.org/nineplanets/nineplanets/hypo.html#planetx
• http://www.todayinsci.com/7/7_24.htm

Hypothetical planets | Lists of planets | Lists of stars | Extrasolar planets

Speculatieve planeet | domnevni planet