Brace yourselves. You are about to hear talk this week of an astronomical non-occurrence of the utmost in obscurity. We’re talking about this weekend’s Blue Moon.
Now, I know what you’re thinking. Isn’t a ‘Blue Moon’ the second Full Moon of the month? How can a Blue Moon fall on the 21st? Trust me, we’re both correct… in a sense. The term ‘Blue Moon’ has taken on several meanings over the last few decades, with the ‘the second Full Moon in a calendar month containing two Full Moons’ now in vogue across ye old Internet. It seems the masses just can’t get enough of Super, Blood, Honey and Moons Black and Blue. We point to last month’s rumored ‘Green Moon‘ as evidence. (Spoiler alert: it wasn’t).
No, we’re talking instead of a Blue Moon in an old-timey sense. You’ll be hard pressed to explain source of this week’s Blue Moon for sure, though it has a fascinating origin story.
The term seems to come down to us from the Maine Farmer’s Almanac, which denoted the ‘third Full Moon in an astronomical season with four as blue.’ The lunar synodic period of 29.5 days — the length of time it takes the Moon to return to a like phase, such as New to New, or Full to Full — means that on most years, there are 12 Full Moons. 29.5 times 12 comes out about 11 days short of a 365.25 day solar year at 354 days, meaning that about every three years, we have a year with 13 Full Moons.
Not a big deal, you say? Well, it assures that lunar based forms of reckoning time, such as the Muslim calendar loses 11 days relative to the Gregorian calendar every year.
Here’s how the 2016 Blue Moon breaks down:
March Equinox- March 20th 4:30 Universal Time (UT)
March Full Moon- March 23rd 12:02 UT
April Full Moon- April 22nd 5:22 UT
May Full Moon- May 21st 21:17 UT (3rd in an astronomical season, ‘blue’)
June Full Moon- June 20th 11:05 UT
June Solstice- June 20th 22:34 UT
The last time we had a season with four Full Moons was August 21st, 2013, and the next Blue Moon under this rule is May 18th, 2019.
Of course, a deeper riddle is just why the Maine Farmer’s Almanac termed this occurrence as Blue, and why they picked the 3rd of a season with 4 specifically… one legend goes that the extra anomalous Full Moon was depicted on the calendar in blue ink to stand out. We’d love to get our hands on a copy of the Old Maine Farmer’s Almanac circa late 19th early 20th century era to see if this was indeed the case. This is on our list of research projects, next time we find ourselves back in our home state of Maine.
Types of Blue Moons
We’ve chronicled the tales of Moons, both Black and Blue. Sky and Telescope also explored the role they had in introducing the modern day Blue Moon into common vernacular. We’ll admit, the ‘2nd in a month with two Full Moons’ is a much easier rule to explain!
Of course, the Moon isn’t scheduled to actually appear blue this week… that’s actually a much rarer occurrence, and the Moon doesn’t need to even be Full for this to happen. In September 23rd, 1950, the residents of the northeastern United States saw the 94% illuminated waxing gibbous Moon rise with a distinctly bluish cast, owing to the high concentration of oily soot particles suspended high in the atmosphere, scattering out red and yellow light but filtering through blue. Reports of similar Blue Moons dot observational lore, though to our knowledge, no one has actually captured an image of such a cerulean apparition of the Moon.
Is the Moon ever really Full? You can make a pretty good argument that the Moon as seen from the Earth is never truly fully illuminated, though it gets really close. Full 100% illumination would occur when the Moon is exactly opposite to the Sun, but when this occurs, the Moon also passes into the dark shadow of the Earth, during a total lunar eclipse.
Fun fact: the next ‘Blue Blood Moon’ lunar eclipse occurs on January 31st, 2018, following the ‘2nd Full Moon in a month with 2′ rule.
The May Full Moon also has the romantic name of the Full Flower, Corn Planting or Milk Moon in Algonquin Indian lore.
In 2016, the Moon continues to follow a shallow path relative to the ecliptic plane, which in turn traces out the Earth’s path around the Sun. 2015 was the bottoming out of the ‘shallow year’ known as a minor lunar standstill, and we’re now headed towards a hilly or steep year of a major lunar standstill in 2025, a time once every 19 years when the Moon rides high in the sky, adding its 5 degree inclination relative to the ecliptic plane.
Will this weekend’s olden times Blue Moon gain traction in today’s fast-paced social media news cycle? Stay tuned!
Do you welcome the extra evening light of the Full Moon, or curse the additional light pollution? Either way, this week’s Full Moon on Friday April 22nd is special. It’s the smallest Full Moon of 2016, something we here at Universe Today have christened the Mini-Moon.
Mini-Moon 2016: This year’s Mini-Moon falls on April 22nd at 5:25 Universal Time (UT), just 13 hours and 19 minutes after lunar apogee the evening prior at 16:06 UT on April 21st. Though apogee on the 21st is 406,350 km distant – a bit on the far end, but the third most distant for the year by 300 km — this week’s Full Moon is the closest to apogee for 2016 time-wise. The 2015 Mini-Moon was even closer, in the 10 hour range, but you’ll have to wait until December 10th, 2030 to find a closer occurance.
What is the Mini-Moon, you might ask? As with the often poorly defined Supermoon, we like to eschew the ambiguous ‘90% of its orbit’ definition, and simply refer to it as a Full Moon occurring within 24 hours of lunar apogee, or its farthest point from the Earth in its orbit.
Fun fact: the 29.55 day period from perigee to perigee (or lunar apogee-to-apogee) is known as an anomalistic month.
Thank our Moon’s wacky orbit for all this lunacy. Inclined 5.14 degrees relative to the ecliptic plane, the Moon returns to the same phase (say, Full back to Full) every 29.53 days, known as a synodic month. The Moon can appear 33.5′ across during perigee, and shrink to 29.4′ across near apogee.
And don’t fear the ‘Green Moon,’ and rumors going ’round ye’ ole internet that promise a jaded Moon will occur in April or May; this is 100% non-reality based, seeking to join the legends of Super, Blood, and Full Moons, Black and Blue.
The April Full Moon is also known as the Full Pink Moon to the Algonquin Indians. The April Full Moon, can, on occasion be the Full Moon ushering in Easter (known as the Paschal Moon) as per the rule established by the 325 AD council of Nicaea, stating Easter falls on the first Sunday after the first Full Moon after the fixed date of the Vernal Equinox of March 21st. Easter can therefore fall as late as April 25th, as next occurs on 2038. The future calculation of Easter by the Church gets the Latin supervillain-sounding name of Computus.
Of course, the astronomical vernal equinox doesn’t always fall on March 21st, and to complicate matters even further, the Eastern Orthodox Church uses the older Julian Calendar and therefore, Easter doesn’t always align with the modern western Gregorian calendar used by the Roman Catholic Church.
The Moon can create further complications in modern timekeeping as well.
Here’s one wonderful example we recently learned of in our current travels. The Islamic calendar is exclusively based on the synodic cycle of the Moon, and loses 11 days a year in relation to the Gregorian solar calendar. Now, Morocco officially adopted Daylight Saving (or Summer) Time in 2007, opting to make the spring forward during the last weekend of March, as does the European Union to the north. However, the country reverts back to standard time during the month of Ramadan… otherwise, the break in the daily fast during summer months would fall towards local midnight.
You can see a curious future situation developing. In 2016, Ramadan runs from sundown June 5th, to July 4th. Each cycle begins with the sighting of the thin waxing crescent Moon. However, as Ramadan falls earlier, you’ll get a bizarre scenario such as 2022, when Morocco springs forward on March 27th, only to fall back to standard time six days later on April 2nd on the start of Ramadan, only to jump forward again one lunation later on April 30th!
Morocco is the only country we’ve come across in our travels that follows such a convoluted convention of timekeeping.
Fun fact #2: the next ‘Mini-Moon’ featuring a lunar eclipse occurs on July 27th 2018.
And the Spring Mini-Moon sets us up for Supermoon season six months later this coming October-November-December. Though lunar perigees less than 24 hours from Full usually occur as a trio, an apogee less than 24 hours from Full is nearly always a solitary affair, owing to the slightly slower motion of the Moon at a farther distance.
Don’t miss the shrunken Mini-Moon rising on the evenings of Thursday April 21st and Friday 22nd, coming to a sky near you.
The post April Lunacy: Getting Ready for the Full ‘Mini-Moon’ appeared first on Universe Today.
Brace yourselves for Blue Moon madness. The month of July 2015 hosts two Full Moons: One on July 2nd and another coming right up this week on Friday, July 31st at 10:43 Universal Time (UT)/6:43 AM EDT. In modern day vernacular, the occurrence of two Full Moons in one calendar month has become known as […]