Is There a Seasonal Blue Moon This Month?

This month, we have a "Blue Moon" on May 31, now popularly defined as a second Full Moon in a calendar month.  But there is also the traditional "Seasonal Blue Moon." 

To understand the complexities of the seasonal variety, you have to step away from our standard 12-month calendar and look at the year the way early astronomers, farmers, and religious officials did. They calculated by a year that was divided strictly by the solstices and equinoxes.

A true astronomical season is the three months between these celestial markers. For example, from the Summer Solstice in June to the Autumnal Equinox in September is the season of Summer.

Because a calendar season is three months long, it naturally contains three full moons. Each of these Full Moons historically had specific names based on folklore and agriculture—like the Harvest Moon, Hunter’s Moon, or Snow Moon—which helped people track planting, harvesting, and seasonal changes.

The lunar cycle (the time from one Full Moon to the next) lasts roughly 29.5 days. If you multiply that by three, a typical season takes about 88.5 days to complete. However, a calendar season is slightly longer, lasting roughly 91 to 92 days. Because of that small 3-day gap, the Full Moons slowly drift backward against the solar calendar. Every 2 to 3 years, the gap catches up, and four full moons manage to squeeze into a single season instead of the usual three.

Well, when a season contained four Full Moons, it created a major naming problem. If you just named them in order, the traditional names would get pushed out of sync with the actual seasons. For example, the "Harvest Moon" might suddenly occur too early, before the crops were actually ready to be brought in. 

To fix this, the Maine Farmers' Almanac introduced a clever rule: the third Full Moon in a four-moon season is designated the Blue Moon. By making the third one a wild card "Blue Moon," the fourth and final full moon of that season could keep its proper traditional name, keeping the rest of the calendar perfectly aligned for the upcoming year.

Complicated, right? 

Because this phenomenon relies on the alignment of the solar year and the lunar cycle, it follows a strict cosmic rhythm known as the Metonic Cycle. The Moon's phases repeat on the exact same calendar days every 19 years. During those 19 years, there are exactly 235 full moons but only 76 seasons. Do the math and you're left with 7 extra Full Moons. Therefore, a Seasonal Blue Moon occurs precisely 7 times every 19 years, making it a true astronomical rarity that perfectly embodies the phrase "once in a Blue Moon."

That Mythological River That You Forgot

I wrote on another blog about forgetfulness in old age and referenced a poem by Billy Collins on the subject. In the poem, he alludes to 

Whatever it is you are struggling to remember
it is not poised on the tip of your tongue,
not even lurking in some obscure corner of your spleen.

It has floated away down a dark mythological river
whose name begins with an L as far as you can recall,

I linked that allusion to this post, hoping that a reader there might come here if they also have forgotten that river.

The mythological river starting with L is Lethe from Greek mythology. It is the perfect river to choose because it is known as the "River of Forgetfulness".

It is one of the five rivers of the Greek underworld. The newly dead were required to drink its waters to completely wash away their memories and earthly life before entering the afterlife or being reincarnated.

The name comes from the Greek word lethe, which translates to "forgetfulness" or "oblivion".

In philosophical traditions like Orphism and Plato's Republic, the river was contrasted with Mnemosyne, the "River of Memory". Initiates were taught to drink from the latter to retain their wisdom and identity.

Did you once know the other 4 rivers of the underworld?
Styx (shuddering/hatred), Acheron (woe), Cocytus (lamentation), and Phlegethon (fire). 

Why Do Some Shirts Have Collars?

I wondered - in my curiosity - if shirts always had collars. 

It seems obvious that they didn't. So, why do some shirts have collars? What purpose do they serve, and when did they first appear? 

Even today, most of us own a shirt with a collar, along with other tops such as a T-shirt, which have no collar at all. 

Let's start our search with the medieval clergy. That tells us that before the 15th century, there were no shirt collars at all.

Back then, shirts were simple undergarments with open, round, or scoop necklines, and long sleeves made of linen or hemp. 

Collars first appeared in the Western world sometime during the mid-to-late 15th century as simple standing bands of fabric around the neckline. I might have guessed that collars were a style of the wealthy. Wrong. 

Members of the clergy often wore stiff tunics with high necks, and adding a collar to the shirt worn beneath the scratchy tunic helped prevent the tunic’s stiff neck from aggravating the skin. Among the clergy, these collars became the only visible part of the shirt.

MacLeod and his collar

Though they originated for practical reasons and became symbols of humility and purity, the clerical collar you would recognize didn't appear until the 19th century, when Scottish Reverend Donald McLeod invented and popularized the clerical collar (informally known as a dog collar) worn by ministers today.

And there have been many collar styles and fashions in the past 700 years.

Time Travel Trivia and Some Spoilers

I love all things about time travel. I'd love to know it's possible to go back or forward in time, but science rarely points to either possibility. 

Science meets pop culture on StarTalk! with host astrophysicist & Hayden Planetarium director Neil deGrasse Tyson, his comic co-hosts, guest celebrities & scientists discuss astronomy, physics, and everything else about life. 

The video embedded here hits on the type of time travel used in A Christmas Carol and whether Ebenezer Scrooge gets pulled through a wormhole.

How about considering how people thought about time travel before Einstein, and how the special theory of relativity changed how we think about time? 

Discover time dilation and how speed and gravity affect an object’s passage of time. And what about those pesky paradoxes of traveling and meddling with the past? 

So many questions!

Is there one immutable timeline or many timelines in a multiverse? Do we have free will? What is time to a photon traveling at the speed of light? How would we police time travel if it were possible? Will we even have time travel in the future? If time travel gets invented, why are we not overrun by tourists from the future? 

Which films depict time travel best? 

How are cells affected by time travel? 

Could we theoretically travel to before the Big Bang, because is there even a place to travel to before the Big Bang?