Following the discovery of the planet Neptune in 1846, there was considerable speculation that another planet might exist beyond its orbit. The search began...

science fiction to refer to hypothetical planets beyond Neptune and Pluto (such as Planet X and even Planet Nine, theorized in 2016). Martin Nilsson (1967)...

extraterrestrials from a planet beyond Neptune called Nibiru. He claimed that Sumerian mythology suggests that this hypothetical planet of Nibiru is in an elongated...

" Hypothetical planets of the Solar System Nemesis (hypothetical star) Planets beyond Neptune Tyche (hypothetical planet) Five-planet Nice model 2017...

up Planet Nine or Planet 9 in Wiktionary, the free dictionary. Ninth planet is a concept related to planets beyond Neptune. Ninth planet or Planet Nine...

unseen or undiscovered planets, which have not coincided with scientific hypotheses (such as hypothesized planets beyond Neptune). In 1918, astrologer...

definition of planet Planet § History Planets beyond Neptune This disambiguation page lists articles associated with the title Twelfth planet. If an internal...

fiction Neptunium Neptune, the Mystic – one of the seven movements in Gustav Holst's Planets suite Timeline of the far future Stats of planets in the Solar...

and expected orbits of Uranus and Neptune suggested that there were one or more additional planets beyond Neptune. The search for these led to the discovery...

Tenth planet is a term formerly applied to possible planets beyond Neptune, before the reclassification of Pluto. It may also refer to: 2060 Chiron, claimed...

asteroid belt, based on computer simulations. Various planets beyond Neptune: Planet Nine, a planet proposed to explain apparent alignments in the orbits...

still be seen as an exhibit. Planets beyond Neptune Planet Nine Vulcan Hubbell, J.G.; Smith, R.W. (November 1992). "Neptune in America – Negotiating a Discovery"...

protostar orbited by a protoplanetary disk. There are eight planets within the Solar System; planets outside of the solar system are also known as exoplanets...

orbits of the planets to the extent that their effects would be easily observable today. Astronomers have hypothesized many planets beyond Neptune, and though...

Fictional planets of the Solar System have been depicted since the 1700s—often but not always corresponding to hypothetical planets that have at one point...

has eight planets by the most restrictive definition of the term: the terrestrial planets Mercury, Venus, Earth, and Mars, and the giant planets Jupiter...

unclear causes. Orbiting bodies and rotation: Are there any non-dwarf planets beyond Neptune? Why do extreme trans-Neptunian objects have elongated orbits? The...

the terrestrial planets could not grow very large. The giant planets (Jupiter, Saturn, Uranus, and Neptune) formed further out, beyond the frost line,...

four such planets in the Solar System: Jupiter, Saturn, Uranus, and Neptune. Many extrasolar giant planets have been identified. Giant planets are sometimes...

works. Disrupted planet Fictional planets of the Solar System Hypothetical planetary object Planet § History Planets beyond Neptune Trans-Neptunian object...

officially used the term minor planet, but that year's meeting reclassified minor planets and comets into dwarf planets and small Solar System bodies (SSSBs)...

trans-Neptunian objects Extreme trans-Neptunian object Planets beyond Neptune 60 minor planets with a semi-major axis greater than 150 AU and perihelion...

A super-Neptune is a planet that is more massive than the planet Neptune. These planets are generally described as being around 5–7 times as large as...

a 2001 non-fiction book by David E. Hoffman Oligarch planet, hypothetical planets beyond Neptune Old Oligarch, author of a "Constitution of the Athenians"...

Pluto (minor-planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of bodies beyond the orbit of Neptune. It is the ninth-largest...

satellites of the giant planets, Titan is tidally locked in synchronous rotation with Saturn, and permanently shows one face to the planet. Consequently, its...

approximately 4.4 Earth masses while Harrington's Planet X was estimated to be 4 Earth masses. Planets beyond Neptune Obituary Betz, Eric (2015-06-09). "An interview...

refer to a region of minor planets beyond Neptune as the "Kuiper belt", since Kuiper had suggested that such small planets or comets may have formed there...

Kelvin–Helmholtz heating Nemesis (hypothetical star) Planet Nine Planets beyond Neptune Vulcan (hypothetical planet) A cold hydrogen-rich gas giant slightly more...

Heliocentrism – Historical models of the Solar System Planets beyond Neptune List of former planets List of hypothetical Solar System objects in astronomy...