Description: 当彗星接近太阳时，冰质彗核中的部分固体物质会变成气体。这些气体主要是水蒸气，但也会含有其他化学物质，如一氧化碳、二氧化碳、氨、甲烷和甲醇。这些气体和尘埃粒子一起环绕着彗核，像一团模糊的球形云，这就是彗星大气，或称彗发。随着彗星越来越接近太阳，越来越多的分子在太阳的紫外线光子作用下裂解，加热彗发，使其外部区域膨胀。最终，彗发的外部区域被电离，并形成彗星的离子尾。

Related Terms:

• 彗星
• 彗核
• 彗尾

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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