greatest elongation

基本解释

Mercury – the solar system's innermost planet – is at its greatest eastern elongation today.
水星——太陽系最裡麪的行星—今天是東部最大的延伸。
At greatest eastern elongation, Mercury swings farthest east of the sun, and briefly appears as an evening "star" after sunset.
這是水星是最大程度的在太陽東部的延伸，這是今晚日落後最簡短的一次顯示。
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.
在它到達最大距角（elongation）時，它將看上去大概爲半明亮、被太陽照明的部分將在持續日子裡減少。
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