Chinese 第九行星 Cited by user 凌雲 on 10 Apr 2024 第九行星（Planet Nine）是位於太陽系外圍的假想行星. 它的引力效應可以解釋一組軌道的特殊聚集，這些天體位於海王星之外，繞太陽運行的平均距離是地球的250倍以上.
Portuguese Planeta Nove Cited by user Leosls on 17 Sep 2021 O Planeta Nove é um planeta hipotético na região externa do Sistema Solar. Seus efeitos gravitacionais poderiam explicar o improvável agrupamento de órbitas para um…
English Planet Nine Cited by user Agmartin on 24 Jul 2017 Planet Nine is a hypothetical large planet in the far outer Solar System, the gravitational effects of which would explain the improbable orbital configuration of a…