The word moon has been around as long as the English language, which is not surprising because the moon was critically important to early civilizations. It comes from the Old English mona and shares a root with the word month—because the moon revolves around the Earth once a month. While the sun stays the same day after day, the moon changes every night, allowing ancient peoples to identify the days and months and seasons.

　　月亮一词的出现时间与英语一样长，这并不奇怪，因为月亮对早期文明至关重要。它来源于古英语mona，和单词month有一个词根，因为月亮每月绕地球旋转一次。当太阳日复一日地停留在同一个地方时，月亮每晚都在变化，这使得古人能够识别出白天、月份和季节。

　　Today, we have calendars and clocks to help us keep track of time. But some of the old names for the moon (especially a full moon) have stuck.

　　今天，我们有日历和时钟来帮助我们跟踪时间。但是一些古老的月球名称(特别是满月)仍然存在。

　　Many, though not all, of these names for moons are linked to traditions related to ecology and ways of life. While you might have heard of some of the names we're referring to, we bet there are lots that will surprise you.

　　有许多月亮的名字是与生态和生活方式有关的传统联系在一起的。虽然你可能听说过一些，但我们敢打赌，有很多名字会让你大吃一惊。

　　blue moon

　　蓝月亮

　　Today, the blue moon is the second full moon in a calendar month. It's awfully rare for a blue moon to come around—it only occurs once every 2.7 years. However, before 1946, when amateur astronomer James High Pruett mistakenly defined the term in Sky&Telescope, a blue moon referred to the third full moon in a season including four full moons (instead of the typical three).

　　如今，蓝月亮是指日历月中的第二个满月。一个月中第二次满月，这是非常罕见的——每2.7年才可能出现一次。然而，1946年以前，业余天文学家JamesHigh Pruett在《天空和望远镜》杂志中错误地定义了这个词，一个季度中出现4次满月时，第3个满月才被称作蓝月亮(而不是典型的三个满月)。

　　The blue in blue moon is thought to come from the old English word be-lǽwa, meaning "betrayer"—possibly because it was out of sync with the usual moon cycle.

　　蓝月亮中的blue被认为源于古老的英语单词be-læwa，意思是“背叛者”——可能是因为它与通常的月球周期不同步。

　　Regardless of the definition, a blue moon is awfully rare—that's where we get the expression once in a blue moon, which is attested to since the 1830s (although it originally had a meaning closer to"never").

　　不管定义如何，蓝月亮是非常罕见的——这就是我们在蓝月亮中得到的表达，这一点自19世纪30年代以来就得到了证实(尽管它最初有一个更接近于“决不”的意思)。

　　Interestingly, there is an earlier version of this expression—to say that the moon is blue. This expression, which dates to the 1520s, meant "to believe in something completely absurd." Another version of this expression from the same time period is to believe the moon is made of green cheese. Cool/Blue moon is just an expression—a blue moon isn't literally blue. However, sometimes the moon can appear blue. If after wildfires or volcanic activity particulates in theat mosphere are the right size, the moon will appear blue or green.

　　有趣的是，这个表达的一个早期版本——认为月亮是蓝色的。这个用法可以追溯到1520年代，意思是“相信一些完全荒谬的东西。”与这个表达处于同一时间段的另一个版本认为月亮是由绿色奶酪制成的。很酷。蓝月亮只是一个表达——蓝月亮不是字面上的月亮是蓝色的。然而，有时月亮可以是蓝色的。在野火或火山活动后，大气中的微粒大小合适，月球就会是蓝色或绿色的。