Planet X

English Etymology X represents an unknown as opposed to the Roman numeral for 10 (initially, Planet X would have been the ninth planet). Pronunciation en /ˈplænɪt ɛks/ Proper noun Planet X en astronomy A hypothetical planet in the Solar system, beyond the currently known outermost planet. The term was applied to Eris for a short while, when Pluto was still considered the ninth planet. en astronomy obsolete A theoretical planet responsible for reported gravitational perturbations of Neptune's orbit. This was initially believed to be Pluto. The reported perturbations were an error. en astronomy obsolete A theoretical planet responsible for observed gravitational perturbations of Uranus' orbit. This planet was discovered and is now known as Neptune. Translations hypothetical planet Chinese: Cantonese: yue X行星 iks1 hang4 sing1, iks1 haang4 sing1 Mandarin: cmn X行星 X xíngxīng Dutch: nl planeet X f Finnish: fi planeetta X French: fr planète X f German: de Transpluto m, de Planet X m Italian: it pianeta X m Japanese: ja 惑星X わくせいエックス, wakusei X 惑星Ｘ Maltese: mt pjaneta X Portuguese: pt Planeta X m Russian: ru Плане́та Х f, ru Плане́та Икс f Slovene: sl planet X m Spanish: es planeta X m Swedish: sv planeten X c Vietnamese: vi hành tinh X See also en Nibiru en Tiamat en Planet Nine Anagrams en aelnptx explant en Obsolete scientific theories Pluto Fictional planets Planets