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Supermoon August 1, 2023

August 02, 2023

Laura and I went to Peggy's Cove to photograph the supermoon rising. As usual the horizon was obscured by a cloud bank so we couldn't see the Supermoon until it was higher in the sky.

The Blue Supermoon will present itself later this month so hopefully we can try again.

A Supermoon by definition is when it is closest to earth and appears larger, about 18%. A Blue Moon is the second full moon in a month.


From Wikipedia, the free encyclopedia
A blue moon during the December 2009 lunar eclipse

A blue moon is an additional full moon that appears in a subdivision of a year: the third of four full moons in a season.

The phrase in modern usage has nothing to do with the actual color of the Moon, although a visually blue Moon (the Moon appearing with a bluish tinge) may occur under certain atmospheric conditions—for instance, if volcanic eruptions or fires release particles in the atmosphere of just the right size to preferentially scatter red light.[1]



The term has traditionally, in the Maine Farmer's Almanac, referred to an "extra" full moon, where a year which usually has 12 full moons has 13 instead. The "blue moon" reference is applied to the third full moon in a season with four full moons,[2] thus correcting the timing of the last month of a season that would have otherwise been expected too early. This happens every two to three years (seven times in the Metonic cycle of 19 years).[3] The author of a March 1946 article in Sky & Telescope attempted to decipher the traditional practice of the editors of the Maine Farmers' Almanac by examining old issues of the almanac. Without enough almanacs to see the correct pattern, he conjectured the wrong rule for 'blue moons', which led to the modern colloquial misunderstanding that a blue moon is a second full moon in a single solar calendar month, with no link to the order it occurs in a season. The phrase "once in a blue moon" is also used idiomatically, which means once after a long time. An example in a sentence: "My sister lives in Alaska, so I only see her once in a blue moon."[4]

Owing to the rarity of a blue moon, the term "blue moon" is used colloquially to mean a rare event, as in the phrase "once in a blue moon".[5][6]

One lunation (an average lunar cycle) is 29.53 days. There are about 365.24 days in a tropical year. Therefore, about 12.37 lunations (365.24 days divided by 29.53 days) occur in a tropical year. In the widely used Gregorian calendar, there are 12 months (the word month is derived from moon[7]) in a year, and normally there is one full moon each month, with the date of the full moon falling back by nearly one day every calendar month. Each calendar year contains roughly 11 days more than the number of days in 12 lunar cycles. The extra days accumulate, so every two or three years (seven times in the 19 year Metonic cycle), there is an extra full moon in the year. The extra full moon necessarily falls in one of the four seasons, giving that season four full moons instead of the usual three, and, hence, a "blue" moon.

  • Folklore named each of the 12 full moons in a year according to its time of year. The occasional 13th full moon that came too early for its season was called a "blue moon", so the rest of the moons that year retained their customary seasonal names.[citation needed]
  • The Maine Farmers' Almanac called the third full moon in a season that had four the "blue moon".[2]
  • The frequency of a blue moon can be calculated as follows: It is the period of time it would take for an extra synodic orbit of the moon to occur in a year. Given that a year is approximately 365.2425 days and a synodic orbit is 29.5309 days,[8] then there are about 12.368 synodic months in a year. For this to add up to another full month would take 1/0.368 years. Thus it would take about 2.716 years, or 2 years, 8 months, and 18 days for another blue moon to occur.
  • Using the common 1946 Sky & Telescope misunderstanding, when one calendar month has two full moons; the second one is called a "blue moon". On rare occasions in a calendar year (as happened in 2010 in time zones east of UTC+07, and in 2018 in almost every time zone) both January and March each have two full moons, so that the second one in each month is called a "blue moon", and the month of February, with only 28 or 29 days, has no full moon.[9] Under this misinterpretation, certain tropical years with 13 full moons, which would normally be said to have one blue moon, can be said to have two blue moons, making blue moons appear to be more frequent.

Supermoon of August 1, 2023

Supermoon Rising Through the Clouds