Description: 在太陽系中有四顆巨行星：木星、土星、天王星和海王星。後兩顆行星，即天王星和海王星，被稱為冰巨行星。它們擁有堅固的岩石核心，外圍則被厚厚的一層水、氨和甲烷包圍。這些化學物質處於一種奇特的高壓狀態，既不是完全固態，也不是完全液態。兩顆行星的外層大氣是由氫和氦組成的厚重氣層。

在早期太陽系中，遠離太陽的區域溫度足夠低，水、甲烷和氨能夠凍結成“冰”。這裡的“冰”是一個廣義術語，指的是由分子組成的凍結化學物質。年輕的天王星和海王星由於引力吸積了這些冰。這些冰是兩顆行星的重要組成部分，因此它們被稱為冰巨行星。

Related Terms:

• 巨行星
• 海神
• 天王星
• 吸積

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This is an automated transliteration of the simplified Chinese translation of this term

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