除2009年12月2日和31日兩次滿月外,下兩次同一個公曆月出現兩次滿月的現象分別是2012年8月2日和31日以及2015年的7月2日和31日。 英文中用“藍月”一詞表述這一天象可以追溯到65年前美國《天空與望遠鏡》月刊中的一次編輯錯誤。但“藍月”將錯就錯地沿用了下來。 “太空”網站主編布裏特介紹說,“如果發生火山噴發,上層大氣中充斥塵粒,就可能出現名副其實的‘藍月’。” Blue moon From Wikipedia, the free encyclopedia 31 December 2009 Blue Moon with partial lunar eclipse This article is about the astronomical phenomenon. For other uses, see Blue Moon (disambiguation). A blue moon is a full moon that is not timed to the regular monthly pattern. Most years have twelve full moons which occur approximately monthly, but in addition to those twelve full lunar cycles, each solar calendar year contains an excess of roughly eleven days compared to the lunar year. The extra days accumulate, so that every two or three years (7 times in the 19-year Metonic cycle), there is an extra full moon. The extra moon is called a "blue moon." Different definitions place the "extra" moon at different times. * In calculating the dates for Lent and Easter, the Clergy identify the Lent Moon. It is thought that historically when the moon's timing was too early, they named an earlier moon as a "betrayer moon" (belewe moon), thus the Lent moon came at its expected time. * Folklore gave each moon a name according to its time of year. A moon which came too early had no folk name – and was called a blue moon – bringing the correct seasonal timings for future moons. * The Farmers' Almanac defined blue moon as an extra full moon that occurred in a season; one season was normally three full moons. If a season had four full moons, then the third full moon was named a blue moon. * Recent popular usage defined a blue moon as the second full moon in a calendar month, stemming from an interpretation error made in 1946 that was discovered in 1999.[1] For example, December 31, 2009 was a blue moon according to this usage.