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A hypothetical planet is a planet whose existence is not known, but has been inferred from observational scientific evidence. Over the years a number of hypothetical planets have been proposed, and many have been disproven. However, even today there is scientific speculation about the possibility of planets yet unknown that may exist beyond the range of our current knowledge.
Within the solar system The solar system is by no means fully mapped and charted. Much of its territory is still unknown, and many astronomers have hypothesised from indirect observation that other substantial objects could still exist undetected in its farthest reaches. Vulcan/Vulcanoids In the 19th century, the astronomer Urbain Le Verrier, credited with the discovery of Neptune, attempted to locate a hypothetical planet within the orbit of Mercury that he believed was causing perturbations in its orbit. This planet, which he named Vulcan after the Roman god of the forge due to its closeness to the Sun, was never observed, and Einstein's general relativity theory subsequently resolved the issue of Mercury's orbit. • However, a gravitationally stable region does exist between Mercury and the Sun, and some astronomers, notably Alan Stern, contend that a field of small minor planets, the Vulcanoids, should exist within it. However repeated observations of the region have yet to yield any results, and the Vulcanoids, if they exist, must be rather small and few in number. • Some conclude that the existence of the Vulcanoids is impossible, as any minor planet within the orbit of Mercury would eventually be destabilised by the Yarkovsky effect; motion by the force of its own heat. • Planet X In the early 20th century, astronomer Percival Lowell's observation of apparent irregularities in the orbits of Uranus and Neptune led him to conclude that a distant planet, which he called Planet X, must lie beyond them. The Lowell Observatory's long search for this planet ultimately led to the discovery of Pluto. However, Pluto's mass was found to be too small to disturb the other planets' orbits significantly, and subsequent measurements by the Voyager 2 spacecraft showed that earlier calculations of Neptune's mass had been in error, leading to the irregularities observed. •Today, few scientists accept Lowell's theory; however, a number of recent observations have reopened the debate on the existence of a "Planet X", even if it would bear little resemblance to that envisioned by Lowell. Theia A onetime Trojan to the Earth that, once its size grew to roughly that of Mars, became unstable in its orbit and collided with the Earth, transforming its crust and upper mantle into a magma ocean, and ejecting massive amounts of light material into orbit, which eventually coalesced into the Moon. This theory is known as the giant impact hypothesis. • Planets between Mars and Jupiter Phaeton A planet situated between the orbits of Mars and Jupiter whose destruction supposedly led to the formation of asteroids and meteorites. One of the first who believed that asteroids are the result of an exploded planet was German astronomer Wilhelm Olbers (1758–1840). The name "Phaeton" for this planet was chosen by the Russian scientist, E. L. Krinov. Nowadays this hypothesis is disregarded by the main scientific community. Tiamat Tiamat is the name of a planet theorized by a handful of fringe scientists to have existed between Mars and Jupiter. They postulate that it was a thriving world in a much differently shaped solar system, with jungles and oceans, whose orbit was disrupted by the arrival of a large planet or very small star (less then twenty times the size of Jupiter) which passed through the solar system between 65 million and four billion years ago. The new orbits caused Tiamat to collide this object, which is known as Nibiru. The debris from this collision are thought by the theory's proponents to have variously formed the asteroid belt, the moon, and the current incarnation of the planet Earth. Nibiru To the Babylonians, Nibiru was the celestial body or region sometimes associated with the god Marduk. The word is Akkadian and the meaning is uncertain. Because of this, the hypothetical planet Nibiru is sometimes also referred to as Marduk. Hypothetical extrasolar planets See also | ||||||||
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