elongation greatest eastern的意思|示意

At greatest eastern elongation, Mercury swings farthest east of the sun, and briefly appears as an evening "star" after sunset.

这是水星是最大程度的在太阳东部的延伸，这是今晚日落后最简短的一次显示。

Mercury - the solar system's innermost planet - is at its greatest eastern elongation today.

水星——太阳系最里面的行星—今天是东部最大的延伸。

Don't tarry when looking for Mercury. Even at its greatest eastern elongation, Mercury sets less than 1.5 hours after the sun tonight.

在寻找水星的时候，无须驻足等候。即便处在东大距，日落之后不到1个半小时，水星便下沉了。