Skip to content

Blue Moon: Facts, Myths, and Occurrences

    The Moon in Art and Literature

    Blue moons are a rare and fascinating astronomical phenomenon that has been the subject of much fascination, myth, and legend throughout history. In this article, we will explore what exactly a blue moon is, the myths and legends surrounding it, how often it occurs, and its significance in astrology and astronomy.

    What is a Blue Moon?

    A blue moon is not actually blue in color, despite the name. Instead, it is a term used to describe the second full moon in a calendar month that has two full moons. This phenomenon is relatively rare, occurring only once every 2.7 years, or approximately once every 30 months.

    Blue Moon.

    Blue Moon: Definition, Folklore, and Frequency

    Blue moon is an astronomical term that refers to an extra full moon that appears in a subdivision of a year. This term has nothing to do with the actual color of the moon, but a visually blue moon may occur under certain atmospheric conditions. In this section of this article, we will discuss the definition, folklore, and frequency of the blue moon.

    Definition The term “blue moon” has traditionally referred to an “extra” full moon, where a year that 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, 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.

    Folklore 

    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. The Maine Farmers’ Almanac called the third full moon in a season that had four the “blue moon.”

    Frequency 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 occur in a tropical year. In the widely used Gregorian calendar, there are 12 months 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, 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.

    A big blue moon.

    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, 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.

    The term “blue moon” has nothing to do with the actual color of the moon but refers to an additional full moon that appears in a subdivision of a year. The frequency of a blue moon is relatively rare, occurring every two to three years, seven times in the Metonic cycle of 19 years. Folklore has named each of the 12 full moons in a year according to its time of year, and the occasional 13th full moon that came too early for its season was called a “blue moon.”

    The Origins of the Term

    The term “blue moon” has been in use for over 400 years, and its origins are uncertain. Some believe it comes from the Old English word “belewe,” meaning “betray,” while others suggest it may have derived from the phrase “betrayer moon,” which referred to an extra moon that upset the usual lunar cycle used for calculating the dates of religious festivals.

    A blue moon in the sky.

    Blue Moon: Origin and Meaning in the English Language

    Blue moon is a term that has been used in the English language for centuries. Its origins can be traced back to a pamphlet published in 1528, called Rede me and be not wrothe, for I say no thynge but trothe, written by William Roy and Jerome Barlow, two converted Greenwich friars. The term was used in a derogatory manner to criticize the Roman clergy, and specifically Cardinal Thomas Wolsey.

    The phrase “blue moon” was used in the pamphlet as a metaphor for something that is absurd or impossible to believe. The context of the passage is a dialogue between two priest’s servants, named Watkyn and Jeffrey. In the conversation, Jeffrey makes the ridiculous statement that the moon is blue, implying that the clergy expect people to believe even in statements that are patently false. The relevant passage reads, “Yf they say the mone is blewe / We must beleve that it is true / Admittynge their interpretacion.”

    Over the years, the term blue moon has evolved to have a different meaning altogether. In modern times, a blue moon refers to the second full moon that occurs within a calendar month. This definition gained popularity in the 1940s and has since become the most widely accepted definition.

    The astronomical definition of a blue moon is slightly different from the modern definition. According to this definition, a blue moon is the third full moon that occurs within a single season that has four full moons. This definition is rarely used, as it is not as widely known or accepted as the modern definition.

    The term “blue moon” has also been used in popular culture. It has been used in literature, music, and movies, often to refer to something rare or unusual. In the song “Blue Moon,” which was written by Richard Rodgers and Lorenz Hart in 1934, the term is used to describe a romantic encounter that is unlikely to happen again.

    In conclusion, the term blue moon has an interesting history that dates back to the 16th century. Its original usage was as a metaphor for something absurd or impossible to believe. Over time, the term has evolved to refer to a second full moon that occurs within a calendar month. Despite its changing definition, the term remains a popular and enduring part of the English language, and it is likely to continue to be used in popular culture for many years to come.

    Blue Moon Myths and Legends

    People and a blue moon.

    The term “Blue Moon” has been used for centuries to describe a rare event, and it has been associated with several myths and legends. Here are some of the most popular ones:

    1. Two full moons in one month: One of the most common myths about the Blue Moon is that it is the second full moon in a calendar month. This definition was first popularized in the 1940s by a misinterpretation of an article in Sky & Telescope magazine. However, this definition is not the original meaning of a Blue Moon.
    2. Rare event: The original definition of a Blue Moon is the third full moon in a season that has four full moons. This definition dates back to the Maine Farmer’s Almanac in the early 19th century. Since seasons usually have only three full moons, a season with four full moons was considered rare and special.
    3. Magical powers: In some cultures, the Blue Moon is believed to have magical powers. For example, in Native American folklore, the Blue Moon is a time when spirits and ancestors can be communicated with, and wishes can be granted.
    4. Prophecies and omens: In some cultures, the Blue Moon is seen as a sign of significant events to come, both good and bad. Some ancient cultures believed that the Blue Moon was a warning of impending disaster, while others saw it as a sign of good fortune.
    5. Love and romance: In popular culture, the Blue Moon is often associated with love and romance. The phrase “once in a Blue Moon” is often used to describe something rare and special, such as a chance encounter with a soulmate.

    In summary, the Blue Moon has been associated with a wide range of myths and legends throughout history. Whether it is seen as a rare astronomical event or a time of magical powers and prophecies, the Blue Moon continues to capture our imaginations and inspire our creativity.

    Folklore and Superstitions

    In some cultures, a blue moon is seen as a sign of impending doom, while in others, it is considered a time of heightened spiritual energy. In medieval Europe, people believed that a blue moon was a sign of disaster, famine, or disease. In modern times, some people believe that a blue moon is a time when wishes are more likely to come true or when you should take risks and make bold decisions.

    Songs and Literature

    The term “blue moon” has also appeared in numerous songs and pieces of literature. The most famous example is the song “Blue Moon,” written by Richard Rodgers and Lorenz Hart in 1934. The song has been covered by countless artists and has become a timeless classic.

    A blue moon and some trees.

    How Often Does a Blue Moon Occur?

    As mentioned earlier, a blue moon occurs approximately once every 2.7 years. However, the exact timing of a blue moon depends on the length of each month and the timing of the full moon.

    When is the Next Blue Moon?

    The next Blue Moon will occur on August 31, 2023.

    Calendar Months

    A calendar month typically lasts for 30 or 31 days, which means that there is usually only one full moon per month. However, because the lunar cycle is approximately 29.5 days long, there are sometimes two full moons in a calendar month, which is when a blue moon occurs.

    Lunar Months

    A lunar month, on the other hand, is the time it takes for the moon to complete one orbit around the Earth, which is approximately 29.5 days. Because the lunar month is slightly shorter than the calendar month, a blue moon can also occur when there are two full moons within a single lunar month.

    Astrological symbols.

    Blue Moons in Astrology and Astronomy

    Blue moons have significance in both astrology and astronomy.

    Astrology

    In astrology, a blue moon is seen as a time of heightened spiritual energy and a time to set intentions and manifest dreams. It is also considered a powerful time for cleansing and releasing negative energy.

    Astronomy

    In astronomy, a blue moon is a rare occurrence that is of scientific interest. It provides an opportunity to study the moon and its impact on tides and other natural phenomena.

    Harnessing the Power of Crystals: Blue Moon Edition

    Crystals and the Moon.

    Have you ever heard of the phrase “once in a blue moon”? This rare celestial event occurs when there are two full moons within the same calendar month, and it holds a special energy that you can tap into using crystals. In this article, we’ll explore the top crystals associated with a blue moon and how they can help you harness its power.

    Clear Quartz: Amplifying Energy 

    As one of the most versatile and popular crystals, clear quartz is known for its ability to amplify the energy of other crystals around it. During a blue moon, clear quartz can help you harness the heightened energy and make the most of it. You can carry a clear quartz with you, meditate with it, or even place it on your altar to enhance the power of your rituals.

    Moonstone: Connecting with the Divine Feminine 

    Moonstone is a crystal that’s closely associated with the moon and its feminine energy. It’s known for its ability to enhance intuition, balance emotions, and promote new beginnings. During a blue moon, moonstone can help you connect with the divine feminine and tap into your intuition. You can wear moonstone jewelry or place a moonstone on your third eye during meditation to enhance your spiritual practices.

    Tigers Eye: Protection 

    Tigers Eye is a powerful crystal that’s often used for protection. It’s known for its ability to enhance courage, strength, and personal power. During a blue moon, tigers eye can help you stay grounded and protected from negative energies. You can carry a tigers eye with you or place it in your home or office to create a shield of protection.

    Lapis Lazuli: Wisdom 

    Lapis Lazuli is a beautiful blue crystal that’s often associated with wisdom, truth, and spiritual awareness. It’s known for its ability to enhance intellectual abilities and intuition. During a blue moon, lapis lazuli can help you tap into your inner wisdom and enhance your spiritual practices. You can wear lapis lazuli jewelry or place a lapis lazuli on your third eye during meditation to enhance your intuition.

    Rose Quartz: Love 

    Rose Quartz is a crystal that’s often associated with love, compassion, and emotional healing. It’s known for its ability to enhance relationships, promote self-love, and attract new love into your life. During a blue moon, rose quartz can help you open your heart and connect with the love that surrounds you. You can carry a rose quartz with you or place it on your heart chakra during meditation to enhance your self-love and relationships.

    Aquamarine (communication)

    Aquamarine (communication) and a blue moon.

    Aquamarine is widely known for its ability to calm and soothe the mind and emotions. It is believed to help alleviate stress and anxiety, promote relaxation, and enhance communication skills. This gemstone is also said to stimulate the throat chakra, which is responsible for communication and self-expression.

    Aquamarine is a powerful and beautiful gemstone that is associated with the Blue Moon and has been revered for centuries for its calming and soothing energies. Whether you wear it as jewelry or use it in your spiritual practices, this crystal is sure to promote clear and effective communication in your life.

    The Maine Farmers’ Almanac and Blue Moons

    The Maine Farmers’ Almanac used the term blue moon to refer to the third full moon in a quarter of the year when there were four full moons instead of the usual three. Farmers would use the almanac’s blue moon dates to schedule their planting and harvesting, as different crops were best planted and harvested at different times of the year.

    The Almanac’s Full Moon Names

    The Maine Farmers’ Almanac also gave full moon names to each lunation in a season. The seasons used were those of the mean tropical year, which is equal in length, as opposed to the astronomical seasons, which vary in length due to the Earth’s speed in its orbit around the sun not being uniform.

    For example, in 1983, the equal seasons began at different times than the astronomical seasons. The equal seasons began at 1:48 AM on March 23, 9:15 AM on June 22, 4:42 PM on September 21, and 12:10 AM on December 22. The astronomical seasons, on the other hand, began at 4:39 AM on March 21, 11:09 PM on June 21, 2:42 PM on September 23, and 10:30 AM on December 22.

    Why the Third Full Moon was Called the Blue Moon

    When a season had four full moons, the third full moon was called the blue moon so that the last full moon could continue to be called by the proper name for that season. This was done to avoid confusion and ensure that farmers knew which full moon was which.

    While blue moons are now commonly associated with the second full moon in a month, their origins lie in the Maine Farmers’ Almanac and the need for farmers to have a reliable guide for planting and harvesting crops. Despite the change in meaning over time, the term blue moon continues to capture our imagination and add a sense of mystery to the night sky.

    A big blue moon in the sky.

    The Mystical Blue Moon Phenomenon Explained

    Have you ever heard the phrase “once in a blue moon”? It’s often used to describe a rare occurrence, but what exactly is a blue moon, and why is it so rare? In this article, we’ll explore the science behind the mystical blue moon phenomenon.

    Causes of Blue Moons

    Forest fires and volcanic eruptions are the two main natural events that can cause a blue moon. The eruption of Krakatoa in 1883 is perhaps the most famous example of this phenomenon. The resulting ash and dust clouds threw particles into the atmosphere that were just the right size (about 1 micrometer in diameter) to scatter red and yellow light, resulting in a blue moon that lasted for nearly two years.

    Other volcanic eruptions have also caused blue moons. The El Chichón volcano in Mexico produced blue moons in 1983, while Mount St. Helens in 1980 and Mount Pinatubo in 1991 caused similar phenomena. Forest fires can also cause blue moons, as seen in Alberta, Canada, in 1950 when several muskeg fires suddenly blew up into major fires, producing large quantities of oily droplets of just the right size to scatter red and yellow light.

    The Science Behind Blue Moons

    The key to a blue moon is the presence of many particles that are slightly wider than the wavelength of red light (0.7 micrometer) and no other sizes present. This combination of particle size is rare, and that’s why blue moons are so unusual. When these particles are present in the atmosphere, they scatter the red and yellow light, making the moon appear blue.

    It’s worth noting that ash and dust clouds thrown into the atmosphere by fires and storms usually contain a mixture of particles with a wide range of sizes, with most smaller than 1 micrometer. This kind of cloud makes the moon turn red, and that’s why red moons are far more common than blue moons.

    Blue moon.

    Conclusion

    A blue moon is a rare and awe-inspiring natural phenomenon caused by the presence of particles in the atmosphere that scatter red and yellow light, making the moon appear blue. It’s an occurrence that has fascinated people for centuries and will continue to do so for many more to come. While blue moons may be rare, they are certainly not impossible to witness, and the next time one occurs, be sure to take a moment to appreciate its beauty and wonder.

    Blue Moons Between 2009 and 2037

    Now let’s take a look at the dates when blue moons will occur between 2009 and 2037. It’s important to note that the dates are dependent on the Gregorian calendar and time zones, unlike the astronomical seasonal definition.

    • 2009: December 2 and 31 (partial lunar eclipse visible in some parts of the world), only in time zones west of UTC+05
    • 2010: January 1 (partial lunar eclipse) and 30, only in time zones east of UTC+04:30
    • 2010: March 1 and 30, only in time zones east of and including UTC+07
    • 2012: August 2 and 31, only in time zones west of and including UTC+10
    • 2012: September 1 and 30, only in time zones east of and including UTC+10:30
    • 2015: July 2 and 31
    • 2018: January 2 and 31 (total lunar eclipse visible in some parts of the world), only in time zones west of and including UTC+11
    • 2018: March 2 and 31, only in time zones west of and including UTC+12
    • 2020: October 1 and 31, only in time zones west of and including UTC+10
    • 2020: November 1 and 30 (penumbral lunar eclipse visible in some parts of the world), only in time zones east of and including UTC+9
    • 2028: December 2 and 31 (total lunar eclipse visible in some parts of the world), only in time zones west of UTC+8
    • 2029: January 1 (total lunar eclipse) and 30, only in time zones east of UTC+7
    • 2037: January 1 and 31 (total lunar eclipse visible in some parts of the world), plus March 2 and 31

    Blue Moons and February

    One interesting fact to note is that blue moons cannot occur in February. However, a blue moon can occur in January and the following March if there is no full moon at all in February, as is the case in the years 1999, 2018, and 2037.

    The Next Blue Moon 

    If you’re interested in observing a blue moon for yourself, the next opportunity will be on August 31, 2023, in time zones west of and including UTC+10. After that, the next blue moon will be on May 31, 2026, in time zones east of and including UTC+8.

    The Moon.

    Can the Moon Ever Turn Blue?

    Although a Blue Moon isn’t actually blue, the moon can turn blue on rare occasions. One such occasion is when a volcanic eruption occurs, and ash particles scatter red light, causing the moon to appear blue.

    NASA has documented instances of a Blue Moon occurring after volcanic eruptions. For example, in 1883, the Indonesian volcano Krakatoa erupted and spread ash particles 50 miles (80 kilometers) into the atmosphere. 

    These tiny particles, about one micron in size, acted as a filter, scattering red light and giving the moon a blue-green hue.

    Other volcanic eruptions have also caused Blue Moons, including the 1983 eruption of El Chichon volcano in Mexico and the eruptions of Mt. St. Helens in 1980 and Mount Pinatubo in 1991.

    Big blue moon.

    What Causes a Blue Moon?

    As mentioned earlier, a Blue Moon occurs when two full moons happen within the same calendar month. However, there is another definition of a Blue Moon that is based on seasons.

    A seasonal Blue Moon occurs when there are four full moons in a single season instead of the usual three. Seasons usually last for three months, so a seasonal Blue Moon happens when there are four full moons within a three-month period. This phenomenon occurs because the lunar cycle does not perfectly match the calendar year.

    In Conclusion

    Although a Blue Moon isn’t actually blue, it is still a rare and fascinating phenomenon. It’s a term used to describe the second full moon in a calendar month, which occurs once every 2.7 years on average. A Blue Moon can also occur when volcanic eruptions scatter ash particles, causing the moon to appear blue. Regardless of how it occurs, a Blue Moon is a sight worth seeing.

    stargazing the Moon.

    If you’re planning on stargazing during the Full Moon in 2023, make sure you have the right equipment. Check out our guide to the best telescopes for 2023 for some great options.