About the Book
Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Pages: 53. Chapters: Hypothetical bodies of the Solar System, Hypothetical galaxies, Hypothetical moons, Hypothetical planets, Hypothetical stars, Unidentified astronomical objects, Dyson sphere, Wormhole, Vulcan, Planets beyond Neptune, List of hypothetical Solar System objects, Black dwarf, Nemesis, Giant impact hypothesis, Planetary objects proposed in religion, astrology and ufology, Micro black hole, Fuzzball, Vulcanoid asteroid, Other moons of Earth, Cosmic string, White hole, Quark star, Tyche, Extrasolar moon, Dark galaxy, Exotic star, List of observations of solar and lunar transits of unknown objects, Gravastar, Phaeton, Intermediate-mass black hole, Domain wall, Magnetospheric eternally collapsing object, Messier 102, Hubble Bubble, Interstellar comet, Dark energy star, Fifth planet, Themis, Quark-nova, Neith, Black star, Electroweak star, Dyson-Harrop satellite, Mercury's moon, Planet V, Quasistar, Boson star, Edmond Modeste Lescarbault, Chiron, 3 Cassiopeiae, NGC 1554, NGC 7522. Excerpt: Following the discovery of the planet Neptune in 1846, there was considerable speculation that another planet might exist beyond its orbit. The search began in the mid-19th century but culminated at the start of the 20th with Percival Lowell's quest for Planet X. Lowell proposed the Planet X hypothesis to explain apparent discrepancies in the orbits of the gas giants, particularly Uranus and Neptune, speculating that the gravity of a large unseen ninth planet could have perturbed Uranus enough to account for the irregularities. Clyde Tombaugh's discovery of Pluto in 1930 appeared to validate Lowell's hypothesis, and Pluto was officially considered the ninth planet until 2006. In 1978, however, Pluto was found to be too small for its gravity to affect the gas giants, resulting in a brief search for a tenth planet. The search was largely aban...
