exosphere

1.Last is the exosphere, which is the outermost layer of the atmosphere.

是散逸层，这是大气的外层。

2.Europa, Ganymede, and Callisto all provide evidence of a thin atmospheric layer known as a 'surface-bound exosphere'.

木卫二、木卫三、木卫四都被证实了有一层很薄的大气层。