Glossary term: 外行星
Description: 在太阳系中，外行星包括木星、土星、天王星和海王星。它们的轨道都在小行星带之外，并且所有这些行星都是所谓的巨行星，它们的大气层非常厚，主要由氢气构成。这使得它们在物理上与内行星截然不同，内行星都是相对较小的岩质天体，大气层相对稀薄。
对于太阳以外的恒星，其周围的行星并不一定分为具有类似特征的内行星群和外行星群--我们知道有许多恒星的近轨道上至少有一颗气态巨行星，即 "热木星"。
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Term and definition status: The original definition of this term in English have been approved by a research astronomer and a teacher The translation of this term and its definition is still awaiting approval
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木星的自转，作者 Vishal Sharma，印度
Credit: Vishal Sharma/IAU OAE
License: CC-BY-4.0 Creative Commons 署名 4.0 国际 (CC BY 4.0) icons
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Credit: Nicolas Hurez，Paul-Antoine Matrangolo 和 Carl Pennypacker/IAU OAE
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木星、木卫一及其阴影，作者：Ralf Burkart，德国
Credit: Ralf Burkart/IAU OAE
License: CC-BY-4.0 Creative Commons 署名 4.0 国际 (CC BY 4.0) icons
木星
Credit: 美国国家航空航天局、欧空局和 A. Simon（戈达德太空飞行中心） credit link
License: CC-BY-4.0 Creative Commons 署名 4.0 国际 (CC BY 4.0) icons
土星
Credit: 美国国家航空航天局、欧空局、A. Simon（戈达德太空飞行中心）和 M.H. Wong（加州大学伯克利分校） credit link
License: CC-BY-4.0 Creative Commons 署名 4.0 国际 (CC BY 4.0) icons
天王星自然色彩图像
License: PD Public Domain icons
天王星与星环
Credit: 美国国家航空航天局、欧洲航天局和 M. Showalter（SETI 研究所） credit link
License: PD Public Domain icons
海王星
Credit: 美国国家航空航天局 / 喷气推进实验室 / 旅行者号-国际空间站 / 贾斯廷·科沃特 credit link
License: PD Public Domain icons
