What You Need To Know About the Blue Moon on Halloween 2020

Despite the dangers of COVID-19, many people in the US are still looking forward to Halloween in 2020. Even though people may likely limit parties, trick-or-treating, and other celebrations on October 31st, Halloween 2020 will still be special due to a rare phenomenon:

The Blue Moon.

Unfamiliar with the Blue Moon? No need to worry. In this post, you’ll learn everything you need to know about the Blue Moon, starting from what it is right down to when it occurs.

What is a Blue Moon?

To better understand what a Blue Moon is and how it happens, you must first have a better understanding of the Moon’s orbit around the Earth, lunar cycles, and even the different seasons of each year.

Under normal circumstances, a full Moon occurs only 12 times each year. This equates to one full Moon each month, or three full Moons for each of the four seasons: spring, summer, fall, and winter.

There are 12 full Moons in a year or one full Moon each month because it takes about 27 days for the Moon to orbit the Earth. Meanwhile, the Moon takes around 29.5 days to complete its lunar phase or the transition period between new Moons. The moon completes 12 orbits around the Earth each year (One orbit equals one full moon.).

A Blue Moon occurs when there are 13 full moons in a year instead of the usual 12. 

However, keep in mind that there are now two accepted definitions of the term “Blue Moon”. There’s the seasonal (and traditional) definition and there’s the more modern definition. The former is the actual definition while the latter is a mistaken definition that is nonetheless accepted today.

Why are there two definitions of the term “Blue Moon”?

Based on the seasonal definition, the term “Blue Moon” refers to the third full Moon in a season that has four full Moons (instead of the usual three full Moons.) The Maine Farmer’s Almanac introduced this definition in the 1930s, and it is the correct definition of the term “Blue Moon”

On the other hand, the modern (incorrect) definition of “Blue Moon” refers to the second full Moon in a month that has two full Moons. This definition was borne out of an amateur astronomer’s misunderstanding of the practices that Maine Farmer’s Almanac editors used to predict the pattern of Blue Moons.

In March 1946, amateur astronomer James Hugh Pruett wrote an article for Sky & Telescope, a monthly astronomy magazine published in the US. In the article, Pruett mistakenly stated that if there were 13 full moons in a year, then that year would have 11 months with one full moon and one month with two full moons—the second full moon being the “Blue Moon”

His exact text in the article was:

“….seven times in 19 years there were—and still are—13 full moons in a year. This gives 11 months with one full moon each and one with two. This second in a month, so I interpret it, was called “Blue Moon”.

This definition of Blue Moon is incorrect, and here’s the simplest example that disproves Pruett’s interpretation: In 2018, February had no full Moon, but both January and March had two full Moons.

After the publication of his article, the use of Pruett’s incorrect definition became widespread. 74 years later, it’s Pruett’s definition of Blue Moon that is more popular and accepted by people worldwide.

Why is the third full Moon the Blue Moon?

Under the traditional definition, there are two reasons why the term “Blue Moon” applies to the third full Moon of a season with four full Moons. One reason is that each full Moon has a name that corresponds to when it occurs, which are as follows:

  • January – Wolf Moon
  • February – Snow Moon
  • March – Storm Moon
  • April – Pink Moon
  • May – Flower Moon
  • June – Strawberry Moon
  • July – Buck Moon
  • August – Sturgeon Moon
  • September – Harvest Moon
  • October – Hunter’s Moon
  • November – Beaver’s Moon
  • December – Cold Moon

The third full Moon is called the Blue Moon so that the rest of the full Moons of that year could retain their corresponding seasonal names.

Another reason why the third full Moon is the Blue Moon is the fact there are normally only three Full moons between each season. One season lasts approximately three months and is also the time between each solstice and equinox. When there are four full Moons in one season instead of three, that means the third full Moon came early, so it’s called the Blue Moon.

When does a Blue Moon happen?

According to NASA, a Blue Moon occurs seven times every 19 years. The time between Full Moons is 29 days. However, some months are either 30 or 31 days long, so it’s possible that a month could have two full Moons. This happens every 2.5 to 3 years.

When is the next Blue Moon?

While there is a high likelihood of COVID-19 negatively affecting Halloween celebrations in the US, that doesn’t make Halloween 2020 any less special. On the contrary, Halloween 2020 might be even more special due to a rare phenomenon known as a Blue Moon.

The first full Moon of October happened on October 1st. There will be a second full Moon or Blue Moon on Halloween. People in the US will get to witness a Blue Moon on October 31st, making Halloween an extra special (and spooky) event. This is the first time a Blue Moon will be occurring in the US since March 2018.

Why is it called a Blue Moon?

The term Blue Moon is a misnomer since Blue Moons look the same as any other full Moon. Blue Moons are not actually blue, so the term has nothing to do with color. 

One theory is that the term “Blue Moon” came from the old English term “belewe Moon”, which meant betrayer Moon because the additional full moon betrayed the common perception that there was only one full moon each month. 

This is all speculation, though, and as of today, no one has a definite answer regarding the origin of the term Blue Moon.

How can you make your Halloween even more special?

With the Blue Moon on Halloween, you’ve got the spooky atmosphere covered. The question is: what can you do to make your Halloween even more special?

The answer: complement your costume with Halloween contact lenses. Lens.com has a wide selection of high-quality, FDA-approved Halloween contact lenses that you can wear to add a special touch to your costume.