greatest elongation

基本解释

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。
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。
By the time it arrives at its greatest elongation, it will appear roughly half-illuminated and the amount of its surface illuminated by the Sun will continue to decrease in the days to come.
在它到达最大距角（elongation）时，它将看上去大概为半明亮、被太阳照明的部分将在持续日子里减少。
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