下个月，一起去看蓝月亮

kobe

下个月月底你将有机会亲眼看到所谓的“蓝月亮”，但什么是“蓝月亮”？也许你听过这个：“once in a Blue Moon(千载难逢的机会)”，到底出现蓝月亮的几率有多小，多特别呢？

如果讲到蓝月亮的话，有几个必须要清楚的信息。一，蓝月亮并不是蓝色的，其实跟平常满月时的月亮颜色差不多。二，对于蓝月亮的定义一直是有争议的。比如，如果你是一个纯化论者(纯粹主义者)，下个月出现的蓝月亮并不是真正意义上的蓝月亮。

一般来说，会按照时间顺序和月相变化将四季和公历月尽可能的互相匹配好。一年分为四个季节，那么每个季节有3次满月；或者一年分为12个月，一个月1次满月。但是大自然的时间总是会和人类设定的时间有一定的不同。因此，有时候一个季节里有4次满月而不是3次，那么一年就会有13次满月。这种现象大约每隔2.7年出现一次。

按照这样的来的话，一个季节中的第4次满月被称为蓝月亮。但是，如果根据这个定义，2012是没有蓝月亮的。夏季——即6月21日至9月22日，这个季节只有3个满月啊，为什么大家都说下个月会有蓝月亮呢？原来因为在1946年时，蓝月亮的定义被拓宽了，也就是说，只要在一个月内出现两次满月也可以。这样的话，这一个月的第二次满月亮就被称为蓝月亮。

这个新定义使蓝月亮一年就可以出现一次。但是更有趣的是，也有可能一年出现2次蓝月亮。在1999年时，一月份有2个满月，三月份有两个满月，而二月份一个满月都没有。这样的怪异天象也引起了地理位置和时区的变化。今年，由英国伦敦的0度经线开始，加9个小时(东九区，日本)将在9月经历2个满月(9月1日一次，9月30日一次)，这意味着他们的蓝色月亮将会出现在9月底而不是8月底。

所以那个定义更好呢？这就要取决你问谁了，我(原文作者)觉得以下这个观点我挺赞成的：近年来，对于蓝色月亮的定义一直有分歧。一个季节中的第4个满月是蓝月亮这种说法比较古老，而一个月内的第2次满月这种说法较新。哪种说法更好呢，或者这两个定义中有一个是错的吗？其实，这些一直是民间传说，所以人民的力量是强大的，人们说这两种说法否对，那就是都对的。

心魔作祟

O  原来是这样啊！
我还以为蓝月亮就是蓝色的呢！
好庸俗....

城南小巷

2012来了

kobe

回复 1# kobe


   Have you heard? At the end of next month, you'll have a chance to witness a so-called "Blue Moon" with your very own eyes. But what does that mean, exactly?

You've probably heard the term "once in a Blue Moon" used to refer to rare events — but just how rare is a Blue Moon, really? And what's so special about them in the first place?

Top image by Sabrina Campagna

Here's what you need to know when it comes to Blue Moons. One: they aren't blue (or rather, no more or less blue than any other full Moon). And two: there's some disagreement over the definition of what a "Blue Moon" really is. For instance: if you're a purist, next month's Blue Moon isn't technically a Blue Moon at all.

Generally speaking, seasons and calendar months tend to match up pretty well, chronologically, with the phases of the moon. The year is divided up into four seasons, with three full Moons per season; or, alternatively, twelve months, with one full Moon per month.

But nature has a knack for falling out of sync with humanity's timekeeping methods. Consequently, sometimes one of the season will cram in four full Moons instead of three, giving rise to 13 full Moons in a year instead of the usual 12. This happens, on average, about once every 2.7 years.

Traditionally, it is the third full Moon in a season containing four full Moons that is referred to as a "blue" moon. It bears mentioning that, according to this definition, there is actually no Blue Moon in 2012. The summer season — i.e. the time between the summer solstice (June 21) and the vernal equinox (September 22) contains the standard three full Moons, as do the rest of the year's seasons. So why is everyone calling next month's Moon a blue one?

Because in 1946, the definition of Blue Moon was accidentally expanded to include instances where two full Moons occur in the span of a single calendar month. In cases such as these, the second full Moon of the month (not the third full Moon of a four full-Moon season) is referred to as a Blue Moon.

The newer definition makes it possible for a Blue Moon to occur even during a year with a normal seasonal distribution of full Moons. Interestingly, it also makes it possible for two Blue Moons to occur in a single calendar year. The last time this happened was in 1999, when there were two full Moons in January, two full Moons in March, and no full Moon in February. It also gives rise to weird geography- and timezone-dependent technicalities; this year, time zones east of UTC+09 will experience two full Moons in the month of September instead of August (once on September 1, and again on September 30th), which means that their Blue Moon will actually occur at the end of September, rather than the end of August.