Understanding The Blue Moon
(with dates to 2040)


By Carolyn Brent
(recently revised)

In a Sky and Telescope article we learn the original definition of a Blue Moon is referring to 4 Full Moons in one season. In this instance a season is defined as the time between a Solstice and Equinox or an Equinox and Solstice. (See Table below) There are four seasons in a year and generally three Full Moons in each season or 12 Full Moons per year. Occasionally we find there are 4 Full Moons in one season and 13 Full Moons in a year marking the annual solar and lunar cycle from December Solstice to Solstice.

In more recent times however the term Blue Moon has also been used to describe the occurrence of two Full Moons in a calendar month. Apparently our current understanding of a Blue Moon comes from a 1940’s article that appeared in astronomy magazine suggesting the definition of a Blue Moon was the second Full Moon in a calendar month. This event only happens every two and a half to three years.

In fact, both of these occur with about the same frequency. However, four Full Moons in a season has greater astronomical significance than two Full Moons in a calendar month. This is because our calendar months are not astronomically based on the yearly seasonal cycle or the monthly lunar cycle.

There is a third definition of a Blue Moon suggesting the term Blue Moon may have originated from the bluish tinge the Moon gets when viewed through smoke. In this case, the theory is that someone saw the Moon appearing quite blue through the smoke of a large distant fire (like a forest fire) and therefore the term Blue Moon was literal.

A fourth occurrence that happens with about the same frequency as the first two examples is when we have two Full Moons in a row in the same sign. This only occurs when the first Full Moon is in Zero or One degree of the sign and the next Full Moon is in 28 or 29 degrees of the same sign and it doesn’t necessarily happen each time the Full Moon is in zero degrees of the sign. For example July 24, 2002 we had a Full Moon at 1 degree and 18 minutes of Aquarius, the following month on Aug 22 we had another Full Moon at 29 degrees and 39 minutes of Aquarius. This also happened in 2005 on June 22 when the Full Moon was at Zero Degrees and 51 minutes of Capricorn and then on July 21 it was at 28 degrees and 47 minutes of Capricorn. (See table below).

In all these definitions of a Blue Moon, either as seen through smoke, or the number of Full Moons in a season, or two Full Moons in a month, or two Full Moons in the same sign, the factor that is common to all of them is that these are rare occurrences captivating our imagination. It is important to remember that each Full Moon has its own unique magic and mystery associated with it and is an opportunity to experience greater illumination of our essential divine nature regardless of whether it is a so-called Blue Moon or not.

Below are some Blue Moon dates to ponder. Do you notice a pattern? For the dates that have already passed it might be helpful to note if any of these Timings were especially significant in your personal or collective experience. For example, I found that the December 2002 Full Moon - Blue Moon was beyond the beyond kind of experience for me and for the entire group I was with at the time. The July 2004 two Full Moons in a calendar month Blue Moon was also especially significant for me, however that was also a time that coincided with a powerful Pluto transit to my natal Moon so it was more than likely that particular Full Moon was a further catalyst for the process already underway and less likely that it was the second Full Moon or a Blue Moon that month.

It helps to know that experientially the Moon rises appearing full for three nights, the day before, the day of and the day after the exact Full Moon indicating the potency of the Full Moon Window lasts for three days. Traditionally the Full Moon is the phase of fruition or fulfillment.

The Moon is often associated with the number 13. However the Moon actually connects with the numbers 12, 13 and 19. If you are tracking the Moon return to a certain zodiacal degree, say zero Capricorn, it will return to that degree every 27.3 days and if you divide 27.3 into 365 the closest whole number is 13. If you are tracking the Moon phases from Full Moon to Full Moon or any other phase it returns every 29.5 days. When we divide 29.5 into 365 the closest whole number is 12. So it is only every few years we will actually have 13 Full Moons in either a calendar year or a seasonal year from one December Solstice to then next.

Blue Moon Dates Based on 4 Full Moons in a Season

  • Jun 2000 - Fourth Full Moon in a Season (Mar 20, Apr 18, May 18, Jun 17)
  • Dec 2002 - Fourth Full Moon in a Season (Sep 21, Oct 21, Nov 20, Dec 19)
  • Sep 2005 - Fourth Full Moon in a Season (Jun 22, Jul 21, Aug 19, Sep 18)
  • Jun 2008 - Fourth Full Moon in a Season (Mar 21, Apr 20, May 19, Jun 18)
  • Dec 2010 - Fourth Full Moon in a Season (Sep 23, Oct 23, Nov 21, Dec 21)
  • Sep 2013 - Fourth Full Moon in a Season (Jun 23, Jul 22, Aug 19, Sep 19)
  • Jun 2016 - Fourth Full Moon in a Season (Mar 23, Apr 22, May 21, Jun 20)
  • Jun 2019 - Fourth Full Moon in a Season (Mar 21, Apr 19, May 18, Jun 17)
  • Sep 2021- Fourth Full Moon in a Season (Jun 26, Jul 24, Aug 22, Sep 20)
  • Jun 2024 - Fourth Full Moon in a Season (Jun 22, Jul 21, Aug 19, Sep 18)
  • Jun 2027 - Fourth Full Moon in a Season (Mar 22, Apr 20, May 19, Jun 18)
  • Dec 2029 - Fourth Full Moon in a Season (Sep 22, Oct 22, Nov 21, Dec 20)
  • Jun 2036 - Fourth Full Moon in a Season (Mar 23, Apr 22, May 22, Jun 20)
  • Jun 2038 - Fourth Full Moon in a Season (Mar 21, Apr 29, May 18, Jun 17 +eclipse)
  • Sep 2040 - Fourth Full Moon in a Season (Jun 26 + eclipse, Jul 24, Aug 22, Sep 20)

Full Moon Dates Based on Two Full Moons in a Calendar Month

  • Nov 2001 - Two Full Moons, November 1 and 30
  • Jul 2004 - Two Full Moons, July 2 and 31
  • Jun 2007 - Two Full Moons, June 2 and 30
  • Dec 2009 - Two Full Moons, December 2 and 31
  • Aug 2012 - Two Full Moons, Aug 2 and 31
  • Jul 2015 - Two Full Moons, July 2 and 31
  • Jan 2018 - Two Full Moons, January 2 and 31 with no Full Moon in February
  • Oct 2020 - Two Full Moons, October 1 and 31

Two Consecutive Full Moons In The Same Sign (No Taurus, Gemini, Leo, Cancer

  • Feb 19 2000, O0 6 51 - Mar 20 2000, 29 6 53
  • Jul 24 2002, O0 - 18 - Aug 22 2002, 29 - 39
  • Jun 22 2005, O0 0 51 - Jul 21 2005, 28 0 47
  • Apr 20 2008, O0 8 43 - May 20 2008, 29 8 27
  • Sep 23 2010, O0 1 15 - Oct 23 2010, 29 1 33
  • Jul 22 2013, O0 - 06 - Aug 21 2013, 28 - 11
  • May 21 2016, 01 9 14 - Jun 20 2016, 29 9 33
  • Mar 21 2019, 00 7 29 - Apr 19 2019, 29 7 27
  • Jul 24 2021, O1 - 26 - Aug 22 2021, 29 - 37
  • Jun 21 2024, O1 0 07 - Jul 21 2024, 29 0 09
  • Aug 24 2029, 01 = 12 - Sep 22, 2029, 29 = 57
  • Jul 22 2032, O0 - 30 - Aug 21 2032, 28 - 34
  • May 22 2035, 00 9 57 - Jun 20 2035, 29 9 2
  • Mar 21 2038, 00 7 33 - Apr 19 2038, 29 7 29
  • Jul 24 2040, O1 - 48 - Aug 22 2040, 29 - 53

Sky and Telescope article: What is a Blue Moon? http://skyandtelescope.com/observing/objects/moon/article_127_1.asp

Carolyn Brent
p3@ShamanicAstrology.com
www.ShamanicAstrology.com

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