“once in a blue moon” The Blue Moon is August 31, 2012

The next Blue Moon is August 31, 2012 , be prepared

August 31 is the 243rd day of the year (244th in leap years) in the Gregorian calendar. There are 122 days remaining until the end of the year.

The term blue moon means it occurs two full moons in one calendar month. Since a lunar cycle consists of approximately 29 ½ and one of approximately 365.24 days, there are 11 days per year exceeding the 12 månesyklusene a year (one per month). These accumulating a second moon cycle about every three years (7 every 19 years metons cycle), and one of the months is thus blue moon.

Skywatchers should circle Friday (Aug. 31) on their calendars, for the date offers the last chance to see a so-called “blue moon” for nearly three years.

According to modern folklore, a Blue Moon is the second full moon of a calendar month. Learn how this name came to be, in this post.

Moon shot with blue filter via our friend Jv Noriega Moon shot with blue filter via our friend Jv Noriega

August 2012 is a month with two full moons. And, by popular acclaim, that means it’s a Blue Moon month – but it’s Blue in name only. That’s because a Blue Moon is sometimes defined as the second full moon in a calendar month. The first full moon is August 1. The second full moon is August 31, 2012.

There are two more definitions for Blue Moon. It can be the third of four full moons in a single season. Or, someday, you might see an actual blue-colored moon.

 The August 31 Blue Moon will not be blue in color. This photo was created using special filters. This August 2012 Blue Moon will be called Blue because it is the second full moon of a month. Image via EarthSky Facebook friend Jv Noriega.

Blue moon as second full moon in a month. In recent decades, many people have begun using the name Blue Moon to describe the second full moon of a calendar month.

blue moon can refer to the third full moon in a season with four full moons.[1] Most years have twelve full moons that occur approximately monthly. In addition to those twelve full lunar cycles, each solar calendar year contains roughly eleven days more than the lunar year of 12lunations. The extra days accumulate, so every two or three years (7 times in the 19-year Metonic cycle), there is an extra full moon. Lunisolar calendars have rules about when to insert such an intercalary or embolismic (“leap”) month, and what name it is given; e.g. in the Hebrew calendarthe month Adar is duplicated. The term “blue moon” comes from folklore. Different traditions and conventions place the extra “blue” full moon at different times in the year. In the Hindu calendar, this extra month is called ‘Adhik(extra) masa (month)’. It is also known as purushottam maas, so as to give it a devotional name.

  • 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.[2]
  • Folklore gave each moon a name according to its time of year. A moon that came too early had no folk name, and was called a blue moon, retaining 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.

A “blue moon” is also used colloquially to mean “a rare event”, reflected in the phrase “once in a blue moon”.[3]

Using the Farmers’ Almanac definition of blue moon (meaning the third full moon in a season of four full moons), blue moons occur

  • November 21, 2010
  • August 21, 2013
  • May 21, 2016

Note that by this definition the months of July, August, and September in 2012 contain four full moons, and August 2012 has two full moons. However, the period from the summer solstice to the autumn equinox in 2012 contains only three full moons, as the September 2012 full moon comes after the equinox. Similarly, the December full moon in 2012 comes after the solstice. Thus calendar 2012 has 13 full moons including two in August, yet it contains no blue moon.

The next time New Year’s Eve falls on a Blue Moon (as occurred on 2009 December 31) is after one Metonic cycle, in 2028. At that time there will be a total lunar eclipse.

I might see that one from high above, God willing !

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