Description: 在太阳系中有四颗巨行星：木星、土星、天王星和海王星。后两颗行星，即天王星和海王星，被称为冰巨行星。它们拥有坚固的岩石核心，外围则被厚厚的一层水、氨和甲烷包围。这些化学物质处于一种奇特的高压状态，既不是完全固态，也不是完全液态。两颗行星的外层大气是由氢和氦组成的厚重气层。

在早期太阳系中，远离太阳的区域温度足够低，水、甲烷和氨能够冻结成“冰”。这里的“冰”是一个广义术语，指的是由分子组成的冻结化学物质。年轻的天王星和海王星由于引力吸积了这些冰。这些冰是两颗行星的重要组成部分，因此它们被称为冰巨行星。

Related Terms:

• 巨行星
• 海神
• 天王星
• 吸积

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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