The So-Called Blue Moons of 2018 and 2020

Full Moon, Christmas Day 2015
Full Moon, Christmas Day 2015

In 2020, there will be two Full Moons in October. One of which occurs on Halloween. A Full Moon will occur on Halloween about once every 20 years but a second Full Moon in October will occur about once every 44 years.

The year 2018 brought another relatively rare occurrence: four Full Moons before April 1, none of which occur in the month of February.

The cycle of lunar phases is determined by the particular alignment of the Moon and the Sun with Earth and this cycle has a period of approximately 29.5 days. This is the Moon’s synodic period, from the Greek συνοδος or sunodos, meaning a gathering. In this case the gathering is an alignment and the synodic period is the time between two identical alignments of three celestial objects. Thus the time between two Full Moons—when the Sun and Moon are exactly opposite each other as seen from Earth, is one synodic period or 29.5 days.

The first Full Moon of 2018 occurs on January 1. Although known by many different names across many cultures, this Full Moon is commonly referred to as the Full Moon After Yule or the Wolf Moon. The United States Naval Observatory provides a table of lunar phases for 2018. The times are given in Universal Time so corrects must be made based on your specific time zone. For example, while observing Standard Time, observers in the Midwestern United States must subtract six hours to get Central Standard Time and subtract five hours to get Central Daylight Time.

From the table we find that the first four Full Moons of 2018 occur on January 2 at 2hr 24m UT (8:24 p.m. on January 1 Central Standard Time), January 31 at 7:27 a.m. CST), March 1 at 6:51 p.m. CST, and March 31 at 6:37 a.m. CST. Since February is the only month that has less than 29 days, it is possible for no Full Moons to occur in February. This will occur when a Full Moon occurs on January 30 or 31.

With two Full Moons occurring in October of 2020 and both January and March of 2018, there is a lot of talk about Blue Moons. According to modern folklore, the second Full Moon that occurs within a single month is a Blue Moon. The phrase “once in a Blue Moon” supposedly signifies a rare event, but having two Full Moons in a single moth isn’t terribly rare and even having Blue Moons within three months isn’t especially rare. In fact, according to this definition, which can be traced back to a misinterpretation of an earlier definition of Blue Moon (see my earlier post for details), two Full Moons can occur in one month about once every two years. That doesn’t exactly make this event rare. The fact that February has no Full Moon this year is more rare.

The alignment of our Gregorian calendar and the Moon’s synodic period synchronize to cause such an occurrence once every 19 years. Thus, the last year February had no Full Moon was 1999 and the next time this will happen is 2037. Even more rare, however, is a year in which a 29-day February has no Full Moon. In that case, not only must a Full Moon occur at the end of January, but the year must also be a leap year. The last leap year that had no Full Moon in February was 1608 (the year before Galileo acquire his first telescope!) The next leap year in which February has no Full Moon will be 2572. Now that is a rarity, indeed!

By the way, according to the more traditional definition of a Blue Moon described in the Maine Farmer’s Almanac (and described in a Sky & Telescope article), there are no Blue Moons in 2018. According to this definition, a season must have four Full Moons rather than the more typical three Full Moons. This year, the January 1 Full Moon is the Moon After Yule, the Full Moon on January 31 is the Snow Full Moon, and the Full Moon on March 1 is the Lenten Moon. The next Full Moon on March 31 occurs in spring and is the Egg Moon. The Full Moon occurring before the vernal equinox must be the Lenten Moon and if it is the fourth Full Moon of winter, the Full Moon falling between the Snow Moon and Lenten Moon is the Belewe, or Betrayer, Moon. That Full Moon must always fall between February 20 and 23 in order for another Full Moon to occur before the vernal equinox.

Much of the details surrounding the naming of Full Moons has to do with the determination of Easter since that is the most important moveable holiday on the Christian calendar and seasonal changes and the phases of the Moon had to be precisely determined. As with most things, once you dive deeply into the subject, you find that the rules are intricate and never are as simple as they seem initially.

Full Moons of Folklore

And then there suddenly appeared before me
The only one my
arms will hold.
I heard somebody whisper
“Please adore me”
And when I looked the Moon had turned to gold.
—”Blue Moon,” Rodgers and Hart

Full Moon Names










There are as many names for the Full Moons of each month as there are cultures and this is not a complete listing. Not one of the Full Moons listed above—nor is any Full Moon from any culture—known as a Blue Moon.



Just what is a Blue Moon? Not what most people believe when you ask them for a definition. According to common lore, a Blue Moon is often described as the second Full Moon in a month. Since the Moon has a 29.5 day synodic period of phases, it is possible to have a second Full Moon in some months, but they are not so rare as to warrant a phrase “Once in a Blue Moon.” In fact, there are two Full Moons in a month about once every two years—hardly a rarity. This particular usage of the phrase appears to stem from a misinterpretation of the original meaning and can be traced to the Trivial Pursuit game of the 1980s and a children’s book published the year before the Genus II edition of the game was released.


Of Modern Origin

The earliest known usage of the phrase “blue moon” appears to be 1528, in a pamphlet entitled Rede Me and Be Not Wrothe in which the author writes “Yf they say the mone is belewe We must beleve that it is true.” The expression seems to refers to something so absurd as to be unbelievable or someone so argumentative that he would claim something clearly false is true. There is also a double-meaning in the phrase since belewe translates from the Old English as betrayer and refers to the misplaced Full Moon before Lent—a betrayer third Full Moon—when there are normally four Full Moons in a season. Thus, the third Full Moon in a season that has four is the Blue or Betrayer Full Moon.

Why the third Full Moon? Because the name of the fourth Full Moon must be in accordance with the seasonal change since the name of that Full Moon relates to the impending equinox or solstice. A complete description of how Blue Moons are determined is quite convoluted, but is an interesting example of how calendar reform, religious observances (namely Lent and Easter), and astronomical events are joined together. Read Sky & Telescope’s article.

The modern usage of “Blue Moon” appears to have its origin in the Maine Farmer’s Almanac. Editors at Sky & Telescope, with the assistance of several librarians, obtained 40 copies of the Almanac dating back to the early 1800s and found numerous citations that referred to Blue Moons, but not one of them referred to the second Full Moon of the month. In fact, the Blue Moons always occurred on the 20th – 23rd days of February, May, August, or November! These Full Moons always occur about one month before a seasonal change. A further nuance discovered with additional research revealed that the almanac definition relied on the use of the tropical year, which is measured from one winter solstice (Yule) to the next, instead of using the traditional calendar year. Most tropical years have 12 Full Moons—three per season—but occasionally there are 13 Full Moons with one season having four Full Moons.


Is the Moon Really Made of Green Cheese?

Basically, we have to define exactly what “green” is. In this case, green is not simply the color that has a wavelength of approximately 5,500 Ångstroms, but rather, green refers to something young—in other words, unseasoned or unripened. Therefore, green cheese is unripened, young cheese.

Ayreby cheese The origin of the comparison appears to come from a phrase coined in the sixteenth century, attributed variously to John Heywood in his Proverbes (1546), François Rabelais (c. 1490–1553), and John Frith in 1529. “Green” refers not to the color, but to a young (i.e. green) or immature rounded cheese with a mottled surface and color similar to that of the Moon. As written in Frith’s translation A Pistle to the Christian Reader, “They woulde make men beleue … that ye Moone is made of grene chese” seems to imply that a person is foolish enough to believe anything he is told if he believes the Moon is made of green cheese.


Can the Moon Really Look Blue?

According the the Science@NASA website, there was a time when people saw blue moons almost every night, except some nights when they were green.

In 1883 the Indonesian volcano Krakatoa exploded with the force of a 100-megaton nuclear bomb. Fully 600 km away, people heard the explosion as if a cannon had been fired. Plumes of ash rose to the very top of Earth’s atmosphere. And the Moon turned blue. Some of the ash-clouds were filled with particles about 1 micron (one millionth of a meter) wide—the right size to strongly scatter the red end of the Sun’s spectrum while allowing other colors to pass. White moonbeams shining through the clouds emerged blue, and sometimes green after the red end of the reflected sunlight was scattered.

Blue moons persisted for years after the eruption and people even saw lavender suns. The ash caused “such vivid red sunsets that fire engines were called out in New York, Poughkeepsie, and New Haven to quench the apparent conflagration,” according to volcanologist Scott Rowland at the University of Hawaii. The unsual sights even prompted Edward Munch to paint “The Scream.”

Other volcanoes have produced blue moons, too. People saw blue moons in 1983, for instance, after the eruption of the El Chichon volcano in Mexico and there are reports of blue moons caused by Mt. St. Helens in 1980 and Mount Pinatubo in 1991. The key to a blue moon is having lots of particles slightly wider than the wavelength of red light (0.7 micron) suspended in the air with no other sizes present. This is rare, but volcanoes sometimes spit out such clouds, as can forest fires.

Blue Moons and Lavendar Suns by Sue Ann Bowling, Ph.D.


Now Hear This

Frank Sinatra: Capitol Records Concept Albums
Front row (l to r): Songs for Young Lovers/Swing Easy!, In the Wee Small Hours, Songs for Swingin’ Lovers!, Close to You, A Swingin’ Affair!, Where are You? Back row (l to r): Come Fly With Me, Frank Sinatra Sings for Only the Lonely, Come Dance With Me!, No One Cares, Nice & Easy, Sinatra’s Swingin’ Session!!!, Come Swing With Me, Point of No Return

After switching web hosts and a long break from blog posting, it’s time to inaugurate this new blog and there is no better way to do that than with a celebration of Francis Albert Sinatra. Specifically, the recent purchase of a CD boxed set of the concept albums he recorded with Capitol Records from 1953 to 1961.

Simply put, you need this boxed set in your collection. Not only is it a bargain at $60 for 13 CDs, the collection documents one of the greatest periods of artistic achievement in any field. After bursting on the scene during the era of the big bands, Sinatra set out on his own as a solo artist and almost single-handedly brought about the end of that era. He was the biggest star in the music world, but by the late 1940s tastes were changing and the young girls–the bobby soxers–who propelled The Voice, as he was known, to superstardom were growing up. After a well-publicized affair with movie star Ava Gardner and a divorce from his high school sweetheart, it was clear Sinatra wasn’t the innocent crooner he seemed. His career disintegrated. He lost his fans, his agent, his recording and movie contracts, and he lost his voice due to a vocal chord hemorrhage.

Those early years have been well documented especially now that the 100th anniversary of Frank Sinatra’s birth has passed. What’s important to know is that after being let go by Columbia Records, he was desperate to revive his career and Alan Livingston of Capitol Records was willing to take a chance on the singer many considered a has-been. He happily signed a seven-album deal and the rest is musical history.

The 13 CDs included in this box set are not a definitive collection of Sinatra recordings, but it is not meant to be. All of these recordings have been released previously on compact disc (several times, in fact), but those CDs typically feature “bonus” tracks to increase the length from the standard 16 tracks of 33 1/3 long-playing albums of the era. Those bonus tracks are mostly wonderful recordings in their own right and were often recorded at the same sessions, but they do not fit the mood of the albums. You can easily find other box sets that include all of Sinatra’s 45-rpm singles, rarities, movie recordings, radio and television appearance, and concert performances should you wish to include them in your collection. This box set encompasses only the “concept” albums–recordings intended to be listened to in a single setting in the order in which they are presented. In fact, one of these albums, In the Wee Small Hours, was the first of the recordings to be pressed in the 16-inch 33 1/3 rpm format and is arguably the first concept album recorded period.

In the Wee Small Hours (1955)
In the Wee Small Hours (1955)

This box set is intended to be the distillation of Frank Sinatra’s artistic vision as presented in the original albums. In that effort, he is masterfully assisted by arrangers Nelson Riddle, Billy May, Gordon Jenkins, and the architect of the 1940 Sinatra sound, Axel Stordahl. Sitting in with Sinatra are a Who’s Who of the best studio musicians of the 1950s.

Remastering analog recordings for a digital medium, especially those recorded on mono two-track tapes, is a tricky business and there are distinct differences in the various releases of these albums. There is general agreement among Sinatra fans, however that the earliest (1980s) CDs of these albums are the best and the remastered “Entertainer of the Century” CDs released after the singer’s death in 1998 are inferior. The recordings used to make this Concepts box set are the same as the superior 1980s CDs. As seen in the photos, each CD slip case is a miniature reproduction of the original album cover art and the CDs are color coordinated to match the slip covers. They are also reproduced in a style that gives a nod to the more collectable “gray label” high-fidelity vinyl records of the era.

Having said this box set is a faithful reproduction of the original albums, there are a couple of exceptions and oddities. One anomaly regarding the various versions of the remastered album occurs on “In the Wee Small Hours,” but it is definitely to the benefit of the consumer. This set’s disc contains Sinatra’s magnificent recording of “Last Night When We Were Young,” which was inexplicably left off the superior 1980s remastering, but restored to its rightful place on the 1990s “Entertainer of the Century” CD re-issue. While this boxed set CD seems to be the 1980s version with regard to the sonic quality of the remastering, the missing track is nonetheless present. Additionally, a few bonus tracks did make their way onto “Sinatra’s Swingin’ Session!!!” (1960), too. I guess Capitol can be forgiven for adding the eight bonus tracks—the album is unusually short with only 12 original song. It clocks in at just over 26 minutes in length.

At this point in his career with Capitol, Sinatra had grown restless and wanted out of his contract. In fact he had already started his own record company (Reprise) and recorded his first album, Ring-A-Ding-Ding!, on his own label. Unable to get a release from his contract, he was obligated to record three remaining albums, including “Sinatra’s Swingin’ Session!!!” Unhappy with the situation, but still a perfectionist in the recording studio, Sinatra quickly ran through the numbers for the album and had Nelson Riddle arrange charts that sometimes didn’t even reach two minutes in length when recorded. Even though they are short, the recordings are still brilliant. The bonus tracks add length and do alter the mood of the original album somewhat, but thankfully includes “I’ve Got the World On a String,” which was recording during Sinatra’s first session with Capitol in 1953 and the first recording in the Riddle style.

If these CDs are not on your shelf or playlist, there’s a sizable hole in your collection.